Method for producing semiconductor component and carrier substrate

Abstract

The invention relates to a method (600) for producing a semiconductor component (100) having at least one exposed film section, said method (600) comprising the following steps: providing (610) a semiconductor material (102) having a carrier substrate (104) provided with a passivation layer (110), a film layer (108) being arranged on the passivation layer (108), the structure and / or composition of the film layer can be changed by water, and the film layer (110) is covered by a protective layer (114) on the side opposite to the passivation layer (108); removing (620) a portion of the carrier substrate (104) using a wet chemical method in order to obtain an exposed region of the passivation layer (108) in the structured region (130) of the semiconductor material (102); and exposing (630) a section of the film layer (110) in the structured region (130) by means of a first dry etching step for etching the passivation layer and a second dry etching step for etching the protective layer to obtain an exposed film section (140).

Description

[0001] According to the main claim, the invention relates to a method and an apparatus for producing a semiconductor device.

[0002] In the context of producing semiconductor components having membranes, a device for converting mechanical energy into electrical energy and a method for producing the same are known from DE 10 2011 005 249 A1. The production of a curved piezoelectric membrane is described therein.

[0003] JP 2013-160706 A discloses a flow sensor on a semiconductor substrate with a free-standing sensor area.

[0004] For modern semiconductor devices, the flexibility in material properties is usually high, so that, for example, in optical semiconductor devices, a good deflection of the light beam can be achieved. In the sense of the present invention, a semiconductor device can be understood as a device manufactured on a semiconductor substrate as a carrier substrate, such as a semiconductor wafer, such as a silicon wafer. The device can be a mechanical device and / or an optical device, wherein the semiconductor properties of the substrate can be independent of the function. The device can be: a mechanical device, an optical device, a device for the NIR range, the visible range, the UV range, the EUV range or the X-ray range of electromagnetic waves. Such semiconductor devices can be manufactured using typical technologies in the semiconductor industry. However, the problem here is that some favorable material properties partially belong to material types that can only be processed with difficulty. For example, a material can have good, desirable material properties, such as a specific refractive index, which can particularly interact with another material (such as air) at the interface and thus can deflect or shape electromagnetic radiation particularly well. However, at the same time, this material may also be water-soluble or hydrolyzable, for example, so that some process steps used in common semiconductor manufacturing methods cannot be used to process this material.

[0005] Based on this problem, a possibility is now proposed which enables improved processing and thus the production of semiconductor components having improved properties.

[0006] This object is achieved by the subject matter of the main claim.

[0007] The solution proposed here provides a method for producing a semiconductor component having at least one exposed film section, wherein the method comprises the following steps:

[0008] - providing a semiconductor material having a carrier substrate provided with a passivation layer, wherein a film layer is arranged on the passivation layer, the film layer comprising or consisting of a material whose structure and / or composition can be changed by water, in particular a hydrolyzable material, wherein the film layer is covered by a protective layer on the side opposite to the passivation layer;

[0009] - removing a portion of the carrier substrate using a wet chemical method in order to obtain exposed areas of the passivation layer in the structured areas of the semiconductor material; and

[0010] - Exposing sections of the film layering in the structured region by means of a first dry etching step for etching the passivation layer and a second dry etching step for etching the protective layer to obtain exposed film sections (140).

[0011] The carrier substrate can be understood, for example, as a common substrate, for example, a substrate made of silicon. The carrier substrate can be provided with a passivation layer, which, for example, contains silicon nitride or is formed by such a material. The film layer can be understood as a layer with particularly advantageous properties (for example, in terms of its optical behavior), but the layer has a material that can be changed by water, especially a hydrolyzable material, or is formed by this material. For example, if the material comes into contact with water or the layer formed by this material breaks or tears, the mechanical structure of this material may be degraded. Hydrolysis can be understood as the embedding between water molecules, wherein in the case of water evaporation or vaporization, this material can then precipitate or crystallize again. However, during the hydrolysis process, the material can also be chemically decomposed by contact with water. For example, aluminum nitride can be hydrolyzed to form ammonia. In this article, the protective layer can be understood as the covering of the film layer. Here, the protective layer and the passivation layer (which are advantageously formed of or contain a material which is insoluble in water or whose structure and / or composition cannot be changed by water) can ensure that the film layer is sealed in a fluid-tight manner relative to the environment of the semiconductor device (for example, except for the side edges of the wafer). In this way, it can be ensured that the film layer is not damaged when processing or structuring the area of ​​the carrier substrate or the semiconductor device, and therefore the semiconductor device to be manufactured is not damaged. Wet chemical methods can be understood as one or more process steps of a wet etching method or a wet cleaning method, in which liquid etchants and / or cleaning agents are used to introduce structures into the semiconductor material or to clean the surface of the semiconductor material. Dry etching methods can be understood as following process steps, in which physical or mechanical removal methods or gaseous etchants are used to structure the semiconductor material. In addition, the first dry etching step and the second dry etching step can (but not necessarily) be implemented with the same dry etching method and / or be performed in one process step. It is also advantageous that the two dry etching steps are implemented successively from one side of the semiconductor device. The sequence of the providing, removing and exposing steps can also advantageously be carried out in the order given, wherein the first dry etching step and the second dry etching step are implemented as sub-steps of the exposing step and can also be performed in any order.

[0012] The solution proposed here offers the advantage that by using different etching methods or cleaning methods in different processing stages, it is ensured that the film layers that are sensitive to the etching material or cleaning material used in one of these process steps remain as undamaged as possible. In this way, it is now also possible to use materials for the film layers that are very advantageous for the function of the semiconductor component to be produced. The solution proposed here thus allows for considerable flexibility in the use of different materials that have very advantageous properties for the desired target application of the semiconductor component.

[0013] Advantageous is the following embodiment of the solution proposed here, in which a semiconductor material is provided in the providing step, in which a protective layer with a covering layer forms a stack as a protective layer, wherein the material of the protective layer is different from the material of the covering layer, in particular wherein the material of the covering layer comprises a reflective material and / or a metal. Such an embodiment provides the following advantages: by means of different materials of the layers of the protective layer, it is possible to structure this protective layer very flexibly, so that a flexible design of the exposed film layer can also be achieved in a later process step. By using a reflective material for the covering layer, for example, the desired optical properties of the finished semiconductor device can also be achieved. According to one embodiment, the method can also include a step of structuring the protective layer to be performed before the second dry etching step, in particular before the step of removing a part of the carrier substrate, in which the protective layer is exposed at least in some places by removing the covering layer, in particular by using an auxiliary mask, by means of one of these etching methods (for example, the etching method used in the first dry etching step or the second dry etching step) or another etching method (for example, the other etching method or another etching method).

[0014] According to a further embodiment of the solution proposed here, sections of the carrier substrate can be removed in the structured region during the structuring step. Such an embodiment of the solution proposed here offers the possibility of preparing the semiconductor material or the semiconductor component in known efficient processing steps in such a way that only dry etching methods can be used in the subsequent exposure step. In this way, the surface of the film layer that may have been exposed at that time can be prevented from being damaged by etching agents or cleaning agents that are too aggressive for the material of the film layer by the previous processing of the semiconductor material.

[0015] Particularly advantageous is an embodiment of the solution proposed here in which the structuring step is carried out in such a way that the film layer is sealed by the passivation layer and at least a part of the protective layer from wet-chemical etching agents or cleaning agents. This embodiment offers the advantage that the film layer is reliably protected from wet-chemical etching agents and thus prevents damage to the film layer.

[0016] According to another embodiment of the solution proposed here, at least a part of the passivation layer and the protective layer can be removed in the exposure step by means of a dry etching method. This embodiment of the solution proposed here offers the advantage that the dry etching method is already applied during the first exposure of the film layer and the film layer can therefore be protected as well as possible or structured efficiently.

[0017] When the film layering itself is not only exposed but also structured, semiconductor devices that are designed to be particularly fine and very efficient for the purpose of use can be manufactured. For this purpose, for example, through holes can be introduced into the film layering, for example so that an electromagnetic radiation attenuator or an optical structure (for example an aperture structure) can be realized in the film layering in the exposed film segment. Such an aperture structure can have through holes, which have a diameter that is larger than the design light wavelength of the device, in order to form a common aperture. Therefore, according to a particularly advantageous embodiment, the film layering can be at least partially removed in the exposure step to obtain a perforated, exposed film segment, in particular wherein the structured area of ​​the protective layer and / or the photoresist mask applied to the protective layer and / or the cover layer can be used as an etching mask. Such perforations can have through holes, which have a diameter that is larger than the design light wavelength of the device, in order to form a common aperture. It is also possible to provide through holes that have a diameter that is smaller than the design light wavelength of the device, in order to thereby generate evanescent light waves or to act as a short-pass filter. The perforated film segment can be a diffraction grating. It should be noted that in the sense of the present invention, light may also be understood as EUV radiation (English: XUV), UV radiation, visible light and infrared light. The optical function of the device may be provided in any of the wavelength ranges mentioned (design light wavelength).

[0018] Furthermore, according to another embodiment of the proposed approach, in the structuring and exposing step, in the through-through region laterally adjacent to the structured region, the film layer, the carrier substrate, the protective layer, the mask layer and the passivation layer can be removed in such a way that an opening is formed into which no section of the film layer protrudes. Such an embodiment of the proposed approach offers the advantage that further regions of the semiconductor material can also be structured with the method proposed, in which no exposed sections of the film layer are required. In this way, the structuring of the semiconductor material or the semiconductor component can be carried out compactly with a few working steps, whereby the production costs and production time can be reduced.

[0019] Also particularly advantageous is the following embodiment, wherein in the structuring step, a retaining material is applied to the exposed section of the passivation layer in the through-region, wherein in the exposing step, the retaining material is removed after the carrier substrate and the passivation layer are removed in the through-region to form an opening. The retaining material can be understood as a plastic material, such as a photoresist, which can also be used to introduce a structure into the different layers of the semiconductor material. The retaining material can also be applied to the surface of the semiconductor material or semiconductor device together with other materials. By using such a semiconductor material that is directly applied to the passivation layer, it is possible to prevent the debris or fragments of the layer to be removed from falling into the processing space uncontrolled and causing errors in subsequent steps. And this fragment that may be formed due to the continuous reduction in the thickness of the layer to be removed can be supported by the retaining material or remain to be material-matched, thereby making it possible to remove or dissolve these fragments without residue. Here, the retaining material can be advantageously applied to the side of the passivation layer away from the substrate in the region of the through-region provided.

[0020] The following embodiments of the solution proposed here can also be implemented very flexibly, in which the opening is formed in the exposure step in such a way that it has a larger diameter than the opening in the exposed area of ​​the film layer. Such an embodiment offers the advantage that structures of different sizes can be introduced into the semiconductor material in a uniform method or process, so that the desired functions in the semiconductor element can be efficiently realized.

[0021] Semiconductor components with particularly advantageous properties can be realized in particular when, in the providing step, a semiconductor material is provided in which the passivation layer and / or the mask layer at least partially comprises silicon nitride and / or the film layer at least partially comprises aluminum nitride, germanium oxide and / or aluminum oxide and / or in which the cover layer contains a metal, in particular chromium, and / or the protective layer contains silicon and / or silicon nitride. In this way, a semiconductor component designed particularly for optical applications can be realized.

[0022] Particularly advantageously, for implementing the different steps of the scheme proposed herein, an embodiment can be used in which, in the structuring step, a wet etching method is performed as a wet chemical method using potassium hydroxide or tetramethylammonium hydroxide as an etchant and / or a wet chemical cleaning method is performed, and / or in the exposure step a dry etching method is performed using a physical dry etching method, a chemical dry etching method, and / or a physico-chemical dry etching method.

[0023] Advantageously, the thickness of the film layer can be between 5 nm and 1000 nm, particularly advantageously between 10 nm and 500 nm, and very particularly advantageously between 50 nm and 200 nm. Advantageously, the lateral extent of the exposed areas of the films can be between 50 μm and 5000 μm, particularly advantageously between 100 μm and 500 μm. The films can be perforated, for example with a hole grid having a lateral hole spacing of between 50 nm and 5000 nm, advantageously of 100 nm to 1000 nm. The films can be used, for example, to absorb and / or diffract electromagnetic radiation.

[0024] Also advantageous are embodiments of the solution proposed here in which the structured regions of the semiconductor material have edges whose normals have an angle of less than 60°, in particular 54.7°, to the surface normal of the carrier substrate, in particular when the semiconductor material is monocrystalline and the edges are formed by etch-resistant crystal planes. For example, silicon wafers with {100} surfaces can be used. If the edges are formed by {111} and equivalent crystal planes, the angle can be 54.74°.

[0025] Method variants may be implemented, for example, in software or hardware or in a hybrid form of software and hardware, for example as instructions in a control unit or a device.

[0026] The solution proposed here also provides an apparatus, which is formed to facilitate the execution, control or implementation of the steps of the variant of the method proposed here with corresponding devices. The basic purpose of the present invention can also be achieved quickly and efficiently through this implementation variant of the present invention in the form of an apparatus.

[0027] To this end, the device may have: at least one computing unit for processing signals or data; at least one memory unit for storing signals or data; at least one interface to a sensor or actuator, the at least one interface for reading in a sensor signal of a sensor or for outputting a data signal or a control signal to an actuator; and / or at least one communication interface for reading in or outputting data embedded in a communication protocol. The computing unit may be, for example, a signal processor, a microcontroller, etc., wherein the memory unit may be a flash memory, an EEPROM, or a magnetic memory unit. The communication interface may be designed to read in or output data wirelessly and / or wired, wherein a communication interface that can read in or output wired data may, for example, be able to read in data from a corresponding data transmission line or output data to a corresponding data transmission line electrically or optically.

[0028] The device can be an electrical device that processes sensor signals and outputs control signals and / or data signals depending on the sensor signals. The device can have an interface that can be designed in hardware and / or software. In the case of hardware design, these interfaces can be, for example, part of a so-called system ASIC that contains various functions of the device. However, it is also possible that these interfaces are self-owned integrated circuits or are at least partially composed of discrete devices. In the case of software design, these interfaces can be, for example, software modules that exist on a microcontroller together with other software modules.

[0029] Also advantageous is a computer program product or a computer program with a program code, which can be stored on a machine-readable carrier or storage medium (such as a semiconductor memory, hard disk storage or optical storage) and is used to execute, implement and / or control the steps of a method according to one of the above-described embodiments, in particular when the program product or program is implemented on a computer or device.

[0030] Embodiments of the solution proposed here are shown in the drawings and explained in more detail in the following description. In the drawings:

[0031] FIG. 1A to FIG. 1I A plurality of sub-diagrams are shown, which illustrate various cross sections of a semiconductor device to be manufactured according to an embodiment in different process steps;

[0032] A block diagram showing a device according to an embodiment;

[0033] Figure 2 shows a plurality of sub-diagrams which illustrate individual cross sections of a semiconductor device to be manufactured in accordance with further embodiments in different process steps;

[0034] Figure 3 shows a schematic cross section of a stack of layers used as starting materials for a semiconductor device;

[0035] Figure 4 shows a cross section of a structured wafer of starting material as semiconductor material for a semiconductor device;

[0036] Figure 5 Schematic diagram showing REM imaging of a structured AlN film produced using the proposed process flow;

[0037] Figure 6 A flow chart illustrating an embodiment of a method for manufacturing a semiconductor device; and

[0038] Figure 7 A block diagram illustrating an embodiment of an apparatus for fabricating a semiconductor device is shown.

[0039] In the following description of advantageous exemplary embodiments of the invention, identical or similar reference numerals are used for elements which are illustrated in the various figures and act similarly, wherein a repeated description of these elements is omitted.

[0040] FIG. 1 is reproduced as a plurality of sub-diagrams (reproduced as FIG. 1A to FIG. 1I ) shows various cross sections of a semiconductor device 100 to be manufactured according to an embodiment after different process steps.

[0041] exist Figure 1A In the embodiment of the present invention, a semiconductor material 102 is firstly shown in the form of a stack of multiple layers. Here, the semiconductor material 102 includes a carrier substrate 104, which is made of silicon or contains this material, for example. The semiconductor substrate 104 also includes a lower mask layer 106 and a passivation layer 108, which each have silicon nitride (Si3N4) or contain this material, for example. The mask layer 106 and the passivation layer 108 can be formed on the carrier substrate 104 in the same manufacturing step, for example. Arranged on the passivation layer 108 is a film layer 110, which, for example, contains a water-soluble material or is formed by such a material. Alternatively or additionally, the film layer 110 can be or is formed by a material whose structure and / or composition can be changed by water, especially hydrolyzable. A protective layer 112 is arranged on the film layer 110, which, for example, includes a protective layer 114 and a cover layer 116 arranged on the protective layer 114. Here, the protective layer 114 can have a silicon-based semiconductor material and be formed as an etching stop layer. The cover layer 116 may, for example, contain a reflective material and / or a metal (eg, chromium) or be formed from such a material.

[0042] In a first processing step, for example, the cover layer 116, for example a reflective material, is structured, for which purpose, for example, a photoresist can be used, which is exposed corresponding to the structure to be introduced into the cover layer 116. For structuring the cover layer 116, wet etching methods and alternatively or additionally dry etching methods can be used.

[0043] Figure 1B A cross-sectional view of the semiconductor device 100 is shown in a state after the above-described method steps have been performed.

[0044] Thereafter, according to this embodiment, mask layer 106 is structured, for example likewise again by using a photoresist to be exposed and / or by using a wet etching method or alternatively a dry etching method.

[0045] Figure 1C The cross-sectional view of the semiconductor component 100 is shown in a state after carrying out this method step.

[0046] In a further method step, a photoresist is used as an etching mask 120 for structuring in order to achieve different lattice types in the semiconductor component 100. Thus, the substrate lattice type 122 and, on the other hand, the film lattice 124 in further regions can be structured.

[0047] Figure 1D The cross-sectional view of the semiconductor component 100 is shown in a state after carrying out this method step.

[0048] According to the exemplary embodiment for producing a semiconductor device 100 shown in FIG. 1 , a wet etching method is now used in a further method step to etch through the carrier substrate 104. In this case, the wet etching method can be used to form obliquely descending side surfaces in the carrier substrate instead of trenches through the openings in the mask layer 106, as can be achieved using the wet etching method under a corresponding orientation of the crystal structure of the carrier substrate 104. The formation of such side surfaces is very advantageous for optical applications, as will be explained in more detail below. Etching is then carried out until the passivation layer 108 is exposed on the back side, which serves as a stop layer for the wet etching method. In this way, it can be avoided that the water-soluble or water-sensitive film layer 110 is attacked by the wet etching method and thus damaged or destroyed.

[0049] Figure 1E A cross-sectional view of the semiconductor device 100 in a state after the steps of this method are performed is shown. Meanwhile, in this embodiment of manufacturing, this state of the semiconductor device 100 is a final state that can be processed by the steps of the wet etching method. The following steps are performed by using a dry etching method to avoid damaging or destroying the film layer 110 formed of or containing a water-soluble material.

[0050] In a subsequent step, the sacrificial layer can be removed, which in the present embodiment can be the portion of the passivation layer 108 exposed from the back side of the carrier substrate 104 and the portion of the protective layer 114 not covered by the photoresist and / or the cover layer 116 as the etching mask 120. The removal is performed using a dry etching method, since the film layer 110 is now exposed in the structured region 130 and the through-region 132. Through the process steps using the wet etching method, the film layer 110 can also be corroded and damaged in this state, so that according to the solution proposed here, the semiconductor device 100 should only be processed using a dry etching method from this method stage onwards.

[0051] Figure 1F The cross-sectional view of the semiconductor component 100 is shown in a state after carrying out this method step.

[0052] Thereafter, in a further method step, the film layer 110 can be removed in the through-region 132, for example, so that a wider opening 136 is provided through the semiconductor device 100. In addition, in the structured region 130, the exposed film layer 110 can also be removed by means of the structured protective layer 112 (in particular the structured protective layer 114 and the structured cover layer 116), which can be achieved, for example, by the above-acting dry etching method. In this way, the film layer 110 containing water-soluble or water-sensitive materials can be structured as desired. At the same time, very fine structures (for example holes 138) can also be realized in the structured region 130 in the film layer 110, which structures can, for example, make it possible for the exposed film layer 110 to be manufactured later to be formed as a movable element.

[0053] Figure 1G The cross-sectional view of the semiconductor component 100 is shown in a state after carrying out this method step.

[0054] Furthermore, in a subsequent step, the area of ​​the protective layer 112 that is not covered by the etching mask 120 (i.e., the uncovered portion of the protective layer 114 and the cover layer 116) is (dry) etched or removed, thereby providing an exposed film section 140 of the film layer 110, which also has, for example, a fine structure, such as a through hole 138. Here, the diameter of the through hole 138 can also be significantly smaller than the opening 236 in the through region 132.

[0055] Figure 1H The cross-sectional view of the semiconductor component 100 is shown in a state after carrying out this method step.

[0056] Finally, in a subsequent step, etching mask 120 is also removed or (dry) etched and, if necessary, individual parts of semiconductor component 100 are separated.

[0057] Fig. 1I The cross-sectional view of the semiconductor component 100 is shown in a state after carrying out this method step.

[0058] Thus, the sub-diagram of Figure 1 shows a pattern of embodiments of a process flow for fabricating a free-standing, moisture-sensitive structured membrane using sacrificial protection layers and standard CMOS process steps. During all critical steps, the sensitive layer (e.g., membrane layer 110) is protected, thereby enabling the use of wet and therefore cost-effective process steps.

[0059] With the solution proposed here, it is therefore possible to manufacture ultra-thin, independent and structured films as film layers 110 from layer materials that are sensitive to wet processes. In this way, the manufacture of independent, ultra-thin films can still be efficiently achieved, which usually requires multiple wet chemical process steps of wet chemical methods, such as photolithography and wafer cleaning. In order to manufacture independent films, the entire wafer is usually etched by dry etching or wet etching. Dry etching methods such as DRIE (deep reactive ionetching) produce an approximately vertical etching profile through the wafer, while wet etching methods can also produce inclined etching profiles in the etched grooves. For optical applications, it is preferred to use inclined V-shaped side walls achieved by wet etching, so that light is transmitted through the film with a high NA (numerischer Apertur) without shadows on the side walls of the wafer hole. However, if the application requires a film material that is sensitive to wet chemistry, it is difficult or impossible to use a wet etching method. For example, aluminum-based or germanium-based materials may even be water-soluble and therefore unsuitable for most wet processes. In the solution presented here, however, a process flow is proposed that enables the production of almost any independent film material. In addition, a method for producing a structured film is described.

[0060] The manufacture of independent membranes is a widely used technology for MEMS products or optical sensors. Usually, a robust material such as SiN or metal is used as the membrane material or the material of the membrane layer 110. However, depending on the application, it is also desirable to use a more sensitive material. For GeO, AlN or Al x O y , for example, are good candidates for transmissive UV applications and EUV applications based on a good adaptation to the refractive index compared to a vacuum. However, even these materials are soluble in water, so that wet process steps are not directly feasible. Here, a method is now proposed by which independent membranes can be produced, which are formed from almost any structured and moisture-sensitive material and also have inclined side walls with holes etched through the wafer. The side walls are formed by different sacrificial layers, which protect the sensitive layer of the membrane layer 110 from the influence of the wet environment. With this approach, the membrane can be structured and suitable reflective materials can be used for sensing purposes in the VIS range. There are no restrictions on the accuracy of the structuring except for the resolution limits of the lithography tools and etching tools used. Here, a minimum structure size of <200nm is shown, which is within the resolution limits of the tools.

[0061] The solution proposed here can be used particularly advantageously for the production of free-standing, ultra-thin films from materials that are particularly suitable for the UV and EUV ranges. Such materials (especially AlN) are water-soluble or hydrolyzable (especially in thin layers) and are not robust to commonly used cleaning chemicals. The proposed process flow circumvents these limitations.

[0062] In principle, the proposed process flow allows the use of any separable and structurable material as film layer, thus providing a high flexibility in the design of semiconductor devices.

[0063] The proposed process is described with the aid of the processing stages of the semiconductor device shown in the sub-figure of FIG1 . The process comprises different standard process steps, such as coating, photolithography, cleaning, wet etching and dry etching. Using the proposed process route, more wet cleaning steps can be performed, thereby improving the quality of surface defects overall. In particular, it is entirely possible to manufacture the film at least partially using the key step of wet etching.

[0064] An important aspect of the proposal proposed here is the use of protective layers below (SiN) and above the wet-sensitive layers during all wet process steps. These protective layers are eventually etched away. The stack is selected so that individual layers can be selectively etched without etching other mask layers and / or protective layers. Another advantage of the proposed solution or stack is the possibility of setting the optical reflectivity by the selected materials and / or layer thicknesses. The introduction of protective layers, for example, provides the possibility of making the reflectivity almost zero in the case of green light, or achieving the maximum reflectivity only by changing the layer thickness.

[0065] In the proposed process flow, Figure 1F and Figure 1G The steps between the processing stages shown are challenging. When etching through the last individual layer in order to open a larger hole, such as in the area of ​​the through opening 136, the layer slowly becomes thinner. If the remaining layer is too thin (on the order of a few nanometers) to remain intact, the film or here the film layer 110 breaks and rolls into fragments before the etching process is finished. These fragments, which may be formed of moisture-sensitive materials, act as undesirable masking layers in the following processes. For this reason, a further optimized process flow has been developed to avoid these fragments from passing through the larger openings.

[0066] Figure 2 The various cross sections of the semiconductor device 100 to be manufactured according to the embodiment at different process steps are shown in a plurality of sub-diagrams. Figure 1CStarting from the processing state of the semiconductor device 100 shown in FIG. 1 , a light shielding mask 200 is first used in the first intermediate step shown on the right, which is used to remove the protective layer 114 in the through-region 132 by means of a dry etching method in a dry etching step. In this way, the film layer 110 is exposed in the through-region 132. In the subsequent process step, the exposed film layer 110 is removed by means of a wet etching method or a dry etching method. Thereafter, the process according to FIG. 1 is continued again. Figure 1D The process shown in the figure, however, now also additionally applies an etching mask 120 to the now exposed upper passivation layer 108. Therefore, in the following steps, in particular Figure 1F and Figure 1G During the transition between the processing states of the semiconductor device 100 illustrated in FIG. 1 , it is ensured that the upper passivation layer 108 (and also not the previously removed film layer 110 in the through-region 132 ) is now unable to break into debris which could serve as a defective optical mask.

[0067] therefore, Figure 2 A (partial) optimized pattern for avoiding debris is shown, which consists of a moisture sensitive layer at a larger opening. Two new process steps are included in order to selectively etch the layer in the area of ​​the larger membrane opening 136 (i.e., the through-area 132). All other process steps are the same or very similar to the previous process flow in FIG. 1.

[0068] Two additional process steps ( Figure 2 The process of removing the moisture-sensitive layer selectively at the larger openings is shown on the right. Various etching methods can be used. In the process mode, a shadow mask is used, for example, to open the buffer layer. All other processes correspond essentially to the process described previously in FIG. 1 . The only difference is that in the passage to the Figure 1D In the step of etching the semiconductor device of the present invention, a slightly adapted photomask is used so that the larger opening remains closed by the photoresist as etching mask 120. This improved process flow makes it possible to replace the critical step of etching the independent moisture-sensitive layer with the process step of etching the thick (independent) photoresist. This can avoid the generation of fragments or debris during processing, such as those formed by broken, ultra-thin and / or moisture-sensitive materials.

[0069] As an example of a moisture sensitive film material, the feasibility of a process flow using aluminum nitride (AlN) can be demonstrated. AlN can even dissolve in water and / or decompose under the action of water to form ammonia, which is a major challenge for wet process steps. In order to obtain a flat, free-standing AlN film, the layer stress is set to a tensile stress of hundreds of MPa. In this example, silicon or silicon nitride has been used as a protective layer. Chromium has been used as a mask layer and a reflective layer or as a capping layer 116.

[0070] Figure 3 A schematic cross section of a stack of layers used as starting material 102 for semiconductor device 100 is shown, wherein an exemplary stack for producing a free-standing water-soluble AlN film is specified. The AlN layer is subjected to tensile stress. Mask layer 106 and passivation layer 108 can be designed as an etch stop layer, for example, and can include, for example, a 100 nm thick Si3N4 layer. Membrane layer 110 can have AlN with a thickness of, for example, 100 nm. Protective layer 114 can have a thickness of, for example, 50 nm and be shaped as SiN x The capping layer 116 may be formed, for example, as a metal layer (eg, formed of chromium) having a thickness of, for example, 100 nm.

[0071] The proposed process flow avoids subjecting the water-soluble AlN to liquid process steps. The desired V-shaped grooves are etched through the wafer with diluted KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide). The end result is that different types of marks can be produced, i.e., lattices structured in chrome for reflective sensing purposes and lattices structured in separate AlN films for transmission purposes. In addition, larger openings can be provided, for example for cleaning purposes.

[0072] Figure 4 A cross section of a structured wafer is shown as a semiconductor device 100, consisting of reflective Cr marks, larger openings (which enable access to the wafer backside), and transmissive marks on a separate AlN film.

[0073] Here, the lateral size of the Cr marks and the structured holes of the AlN film is limited only by the resolution limit of the lithography tool in combination with the dry etching tool. Structures with lateral sizes of about 100 nm can be achieved. Similar results have been achieved using Al2O3 as a film material that is sensitive to various wet cleaning mixtures. A typical REM (Rasterelektronenmikroskop, scanning electron microscope) image of a structured, free-standing AlN film is shown in the figure below.

[0074] Figure 5 A diagram of a REM image of a structured AlN film 110 produced with the proposed process flow is shown. The circles are holes in the through-regions 132 in the AlN film, which enable a free light path through the film 110 and the entire wafer 104 .

[0075] Figure 6A flow chart of a method 600 is shown for producing a semiconductor device having at least one exposed membrane section, wherein the method comprises a step 610 of providing a semiconductor material having a carrier substrate provided with a passivation layer, wherein a membrane layer is arranged on the passivation layer, the membrane layer having or being formed of a material whose structure and / or composition can be changed by water, in particular a hydrolyzable material, wherein the membrane layer is covered by a protective layer on the side opposite to the passivation layer. Furthermore, the method 600 comprises a step 620 of removing a part of the carrier substrate using a wet chemical method in order to obtain an exposed region of the passivation layer in the structured region of the semiconductor material. Finally, the method 600 comprises a step 630 of exposing a section of the membrane layer in the structured region by means of a first dry etching step for etching the passivation layer and a second dry etching step for etching the protective layer to obtain an exposed membrane section.

[0076] Figure 7 A block diagram of an apparatus 700 for manufacturing a semiconductor device is shown. The apparatus 700 comprises a unit 710 for providing a semiconductor material having a carrier substrate provided with a passivation layer, wherein a film layer is arranged on the passivation layer, the film layer having a water-soluble material or being formed of such a water-soluble material, wherein the film layer is covered by a protective layer on the side opposite to the passivation layer. The apparatus 700 further comprises a unit 720 for structuring the protective layer using a wet etching method to obtain a structured region of the semiconductor material. Finally, the apparatus 700 comprises a unit 730 for exposing a section of the film layer in the structured region using a dry etching method to obtain an exposed film section.

[0077] In summary, it should be noted that an advantageous approach for producing structured, free-standing membranes is presented herein. A process flow is presented that enables the use of materials that are not robust in the chemicals commonly used for cleaning and etching, especially water. A wide selection of materials enables the use of membranes with a lower refractive index and thus lower dispersion. An optimized process flow is also presented to enable larger openings to be achieved without the generation of debris that is usually generated when etching through the membrane.

[0078] All etching steps can be performed selectively to the respective masking layer and the etch stop layer. Despite the use of protective layers, the risk of small defects leading to undesired underetching or corrosion is increased.

[0079] Almost any separable and structureable material can now be used as an alternative film layer, which increases the flexibility of the concept proposed here compared to conventional process steps.

[0080] The process flow according to the invention can also be advantageously carried out on typical MEMS membranes with sensitive materials. In addition, this opens up the possibility of using sensitive materials as membrane layers that cannot be realized with conventional methods.

Claims

1. A method (600) for manufacturing a semiconductor device (100) having at least one film section exposed, wherein the method (600) comprises the following steps: - providing (610) a semiconductor material (102) having a carrier substrate (104) provided with a passivation layer (108), wherein a film layer (110) is arranged on the passivation layer (108), the film layer having or consisting of a material whose structure and / or composition can be changed by water, in particular a hydrolyzable material, wherein the film layer (110) is covered by a protective layer (114) on the side opposite to the passivation layer (108); - removing (620) a portion of the carrier substrate (104) using a wet chemical method in order to obtain exposed areas of the passivation layer (108) in the structured areas (130) of the semiconductor material (102); and - exposing (630) sections of the membrane layering (110) in the structured region (130) by means of a first dry etching step for etching the passivation layer and a second dry etching step for etching the protective layer to obtain the exposed membrane sections (140).

2. The method (600) according to claim 1, characterized in that: In the providing (610) step, the following semiconductor material (102) is provided, in which the protective layer (114) having a covering layer (116) forms a stack as a protective layer (112), wherein the material of the protective layer (114) is different from the material of the covering layer (116), in particular wherein the material of the covering layer (116) comprises a reflective material and / or a metal, and furthermore the method (600) comprises a step of structuring the protective layer (112) to be performed before the second dry etching step, in particular before the step (620) of removing a portion of the carrier substrate, in which the protective layer (114) is exposed at least in certain locations by removing the covering layer (116), in particular by using an auxiliary mask, by means of an etching method used in the first dry etching method or the second dry etching method or another etching method.

3. The method (600) according to any one of the preceding claims, with reference to claim 2, characterized in that: In the structuring and exposing (630) steps, in a through-region (132) laterally adjacent to the structured region (130), the film layer (110), the carrier substrate (104), the protective layer (114) and the passivation layer (108) are removed in such a way that an opening (136) is formed through the semiconductor device (100), in particular, no section of the film layer (110) protrudes into the opening.

4. The method (600) according to claim 3, characterized in that: In order to avoid contamination caused by material residues of the passivation layer to be removed by stripping, a retaining material (210) is applied to the section of the passivation layer (108) exposed in the through-region (132) in the structuring step, wherein in the exposing (630) step, the retaining material (210) is removed after removing the carrier substrate (104) and the passivation layer (108) in the through-region (132) to form the opening (136).

5. The method (600) according to any one of claims 3 or 4, wherein in the exposing (630) step, the opening (136) is formed in such a way that the opening has a larger diameter than the opening (138) in the exposed area (140) of the membrane layer (110).

6. The method (600) according to any one of 2 to 5 above, characterized in that: In the structuring step, a wet etching method is performed as a wet chemical method using potassium hydroxide or tetramethylammonium hydroxide as an etchant, and / or wherein in the exposing (630) step a physical dry etching method, a chemical dry etching method, and / or a physico-chemical dry etching method is used to perform the first dry etching step and / or the second dry etching step.

7. The method (600) according to any one of the preceding claims, characterized in that A plurality of semiconductor components are manufactured simultaneously on the carrier substrate.

8. The method (600) according to any one of the preceding claims, characterized in that Prior to the step of exposing (630) the section of the membrane layer (110), at least one cleaning step with an aqueous cleaning agent, in particular a wet chemical cleaning method, is provided.

9. The method (600) according to any one of the preceding claims, characterized in that In the exposing (630) step, the film layer (110) is at least partially removed to obtain a perforated, exposed film section (140), in particular wherein a structured region (130) of the protective layer (114) and / or a photoresist mask (120) applied to the protective layer (114) and / or the cover layer (116) is used as an etching mask.

10. The method (600) according to any one of the preceding claims, characterized in that In the providing (610) step, the following semiconductor material (102) is provided, in which the passivation layer (108) at least partially comprises silicon nitride, and / or the membrane layer (110) at least partially comprises aluminum nitride, germanium oxide and / or aluminum oxide, and / or the covering layer (116) contains a metal, in particular aluminum or a transition metal, in particular at least one of the transition metals titanium, nickel, chromium, tantalum, tungsten, platinum, and / or the protective layer (114) contains silicon and / or silicon oxide and / or silicon nitride.

11. A method (600) according to any of the preceding claims, wherein the structured region (130) of the semiconductor material (102) has an edge, the normal of which has an angle with the surface normal of the carrier substrate that is less than 60°, in particular 54.7°, in particular wherein the semiconductor material is single crystalline and the edge is formed by an etching-resistant crystal plane.

12. The method (600) according to any one of the preceding claims, characterized in that The film layer (110) has a thickness between 10 nm and 500 nm.

13. A device (700) configured for implementing and / or manipulating the steps (610, 620, 630) of the method (600) according to any one of the preceding claims 1 to 11 in corresponding units (710, 720, 730).

14. A computer program, which is configured to implement and / or operate the steps of the method (600) according to any one of the preceding claims 1 to 11 when the computer program is executed on a computer unit.

15. A carrier substrate (104) for producing at least one semiconductor device (100) having at least one exposed membrane section, the carrier substrate having a passivation layer (108) arranged on a first side, wherein a membrane layer (110) is arranged on the passivation layer (108), the membrane layer having or being formed of a material whose structure and / or composition can be changed by water, in particular a hydrolyzable material, wherein the membrane layer (110) is covered by a protective layer (114) on a side opposite to the passivation layer (108), wherein the protective layer (114) contains silicon and / or silicon nitride, wherein the protective layer (114) with a covering layer (116) forms a stack as a protective layer (112), wherein the material of the protective layer (114) is different from the material of the covering layer (116), and the covering layer (116) contains a metal and furthermore an etching mask is applied on a second side of the carrier substrate opposite to the first side for wet etching of the substrate.

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