Lithography method for producing an electrical component in a wafer, arrangement and use

Abstract

The invention relates to a lithography method for producing an electrical component in a wafer (12). The lithography method comprises: generating a laser beam (20), wherein the laser beam (20) is a pulsed laser beam, wherein the laser pulses of the laser beam (20) have a pulse duration with a value of less than or equal to 100 ns; and producing a physical modification (32) in a portion (34) of the wafer (12) by irradiating the portion (34) with the laser beam (20), wherein an etchability, in particular an etching rate, of the wafer (12) in the portion (34) is changed by the physical modification (32).

Description

[0001] Applicant:

[0002] TRUMPF Laser SE

[0003] Aichhalderstraße 39 78713 Schramberg

[0004] Fraunhofer Society for the Advancement of Applied Research eV Hansastraße 27c 80686 Munich

[0005] 43210231 WO 02.12.2025

[0006] JOC / MAY

[0007] Title: Lithographic process for manufacturing an electrical component in a wafer, arrangement and use

[0008] Description

[0009] The invention relates to a lithography process for manufacturing an electrical component in a wafer, an arrangement and a use.

[0010] Extreme ultraviolet (DUV) light refers to light with a wavelength in the range of 193 nm to 365 nm. DUV light enables the precise and highly accurate imaging of fine structures, which is why it is frequently used in lithography, a process that can therefore be called DUV lithography. Due to its ability to precisely and accurately image fine structures, DUV lithography is well-suited for the production of integrated circuits, particularly microchips.

[0011] The manufacturing of integrated circuits typically employs a lithography process. In this process, a semiconductor substrate is usually coated with a photoresist. The photoresist is then exposed using DUV light. Before reaching the photoresist, the DUV light can pass through a mask that locally blocks the light. This allows the photoresist to be exposed with a specific pattern, resulting in exposed and unexposed areas.

[0012] DUV light typically triggers a chemical reaction in the exposed areas. This allows the molecules of the photoresist to be modified by the DUV light. Preferably, the photoresist contains molecules that are split or divided by exposure to the DUV light, for example, into two or more independent molecules. More generally, local irradiation of the photoresist with DUV light can cause a local chemical change or modification of the photoresist. In particular, the chemical properties of the photoresist can be altered by the DUV light.

[0013] The exposed and unexposed areas can differ in their solubility. This means that the photoresist can be removed from the exposed areas using a developer solution, but not from the unexposed areas. It is also conceivable that the photoresist can be removed from the unexposed areas using the developer solution, but not from the exposed areas. Local removal of the photoresist creates a structure that acts as a local or section-by-section mask of the semiconductor substrate. Masking individual areas or sections allows for the creation of a functional layer within the semiconductor substrate, for example, by etching, and thus the fabrication of integrated circuits.

[0014] The invention aims to provide a lithography process for manufacturing an electrical component in a wafer, an arrangement for manufacturing an electrical component in a wafer, and a use, each of which has improved properties, in particular reducing the use of resources, being environmentally friendly, and reducing the manufacturing time of electrical components.

[0015] The invention solves this problem by providing a lithography process with the features of claim 1, an arrangement with the features of claim 14, and a use with the features of claim 15. Advantageous embodiments and further developments of the invention are set forth in the dependent claims.

[0016] A lithography process according to the invention serves to fabricate an electrical component in a wafer. The lithography process comprises: generating a laser beam, wherein the laser beam is a pulsed laser beam, wherein the laser pulses of the laser beam have a pulse duration of less than or equal to 100 ns (nanoseconds), preferably 10 ns; and producing a physical modification in a section of the wafer by irradiating the section with the laser beam, wherein the physical modification changes the etchability, in particular the etch rate, of the wafer in the section.

[0017] By modifying the etchability through physical modification, the use of photoresist and / or developer, especially for etching the physically modified area, can be reduced or eliminated entirely. Photoresists and / or developers used in lithography are typically environmentally harmful and require costly disposal. By reducing or eliminating the need for photoresist and / or developer, this costly disposal process can be avoided, thus reducing resource consumption and making the lithography process more environmentally friendly. Consequently, the lithography process can be ecologically advantageous.

[0018] Another aspect of the lithography process is that by reducing or saving on photoresist and / or developer solution, especially for etching the section with the physical modification, the manufacturing costs of the electrical component can be reduced, which is why the lithography process is particularly cost-effective.

[0019] Another aspect of the lithography process is that the etchability of the wafer in the selected area is directly modified by the laser beam. The resulting local variation in etchability acts as a mask. Therefore, a process step involving the local removal of photoresist using a developer solution can be eliminated. In other words, the wafer can be etched immediately after the selected area is irradiated. This allows the electrical component to be manufactured more quickly using lithography compared to lithography processes that use photoresist.

[0020] Another advantage of the lithography process is that it eliminates the need for local shading using a mask through which the laser beam passes before impacting the wafer. The use of a mask is not strictly necessary. The laser beam can be guided across the wafer to create both an exposed and an unexposed area.

[0021] Another aspect of the lithography process is that, due to the elimination of photoresist and / or developer solution, especially for etching the section with the physical modification, contamination of the wafer by photoresist and / or developer solution is avoided, thus reducing the cleaning effort required after etching the wafer.

[0022] Another aspect of the lithography process is that the laser beam does not necessarily have to be a DUV laser beam. This can simplify the manufacturing of electrical components, especially if they are relatively large, using the lithography process.

[0023] Preferably, the electrical component can be an integrated circuit, in particular a microchip. Alternatively, the electrical component can be an electronic semiconductor device or an electro-optical semiconductor device. Alternatively, the electrical component can be a microsystem or micro-electromechanical system (abbreviation: MEMS).

[0024] If the electrical component is a MEMS, the lithography process can be particularly advantageous because it eliminates the need to remove photoresist from hard-to-reach areas of the MEMS. This can simplify the cleaning process after MEMS fabrication.

[0025] The wafer can have a semiconductor substrate. The semiconductor substrate can be made of silicon, preferably monocrystalline silicon, silicon carbide, gallium arsenide, and / or indium phosphide. The wafer can be in the form of a circular, rectangular, or square plate. The wafer can have a thickness ranging from 0.3 mm to 3 mm, particularly from 0.8 mm to 1.2 mm. The laser beam can be generated by a laser beam source. The laser beam source can be a solid-state laser.

[0026] The laser beam can be designed to cause the physical modification to occur when the laser beam hits the section.

[0027] The laser beam can have a wavelength in the infrared, visible, or ultraviolet range. In particular, the laser beam can have a wavelength in the range of 1 pm (micrometer) to 11 pm. Alternatively, the wavelength of the laser beam can have a value in the range of 500 nm to 530 nm, preferably 515 nm. Alternatively, the wavelength of the laser beam can have a value less than 355 nm. In particular, the wavelength of the laser beam can have a value in the range of 200 nm to 350 nm. Laser beam sources for such wavelengths may be commercially available.

[0028] The focus size of the laser beam on the wafer can scale linearly with the wavelength of the laser beam. Therefore, shorter wavelengths can be advantageous for the fabrication of small electronic components.

[0029] The laser beam can have a Gaussian or flat-top intensity distribution. A Gaussian intensity distribution allows for a simpler and more compact design. A flat-top intensity distribution achieves a uniform power density across the cross-section of the laser beam, enabling uniform physical modification within that section.

[0030] The laser beam can be formed from a plurality of laser pulses.

[0031] The pulse duration of the laser pulses can be understood as the duration of each laser pulse. The pulse duration of the laser pulses can be less than or equal to 100 ns, preferably 10 ns. The pulse duration of the laser pulses can be in the range of 10 fs (femtoseconds) to 100 ns. Preferably, the pulse duration of the laser pulses can be less than 1 ns or 100 ps (picoseconds). The pulse duration of the laser pulses can be greater than 10 fs, particularly 100 fs. Advantageously, with such a pulse duration, the wafer heats up only minimally, thus preventing damage to the wafer due to thermal effects. In particular, this allows the heat-affected zone to be kept small. A small heat-affected zone enables the production of particularly fine or delicate physical modifications.

[0032] The short pulse duration of the laser pulses allows for precise creation of the physical modification. This short pulse duration results in a short exposure time, enabling optimal resolution and sharpness of the physical modification both laterally and in depth within the wafer. Due to the short timescales, any temperature profile that develops during irradiation of the section is irrelevant.

[0033] The pulse energy of a laser pulse can be understood as the energy present in each laser pulse. The pulse energy of laser pulses can range from 10 pJ (picojoules) to 10 mJ (millijoules). A pulse energy of less than 1 pJ (microjoule) has proven particularly advantageous for producing the desired physical modification. The pulse energy of laser pulses can also exceed 150 nJ. At such pulse energies, the desired physical modification can be produced efficiently.

[0034] The average power of the laser beam can range from 100 mW (milliwatts) to 10 kW (kilowatts).

[0035] Irradiating the section with the laser beam can be done using a fluence or exposure dose with a value in the range of 0.01 J / cm². 2(Joules per square centimeter) up to 1 J / cm² 2 take place.

[0036] The laser beam irradiation of the section can be performed for a duration shorter than the time required for heat conduction and / or mass transport within the wafer. This prevents the wafer from being melted by the laser beam or from undergoing diffusion. In other words, the physical modification can be achieved through a very short interaction between the laser beam and the wafer. This interaction can occur in a shorter timeframe than heat conduction and / or mass transport within the wafer. This is not mandatory.

[0037] The laser beam can be used to irradiate a section by irradiating a surface of the section. Irradiating a section of the wafer can create a local physical modification within the wafer. The section can be referred to as a region of the wafer. The section can be continuous or discontinuous. The section can be a three-dimensional segment of the wafer. The section can be composed of multiple sub-sections.

[0038] Physical modification can be described as a physical change. Physical modification cannot be chemical modification.

[0039] The laser beam cannot be designed to alter the chemical composition of the wafer. In particular, the laser beam cannot be designed to break up a molecule of the wafer, for example, into two independent molecules. The laser beam cannot be designed to induce a photochemical reaction in the wafer material.

[0040] The physical modification can be achieved, in particular only, by irradiating the wafer with the laser beam. The physical modification can be produced during the irradiation of the wafer with the laser beam and / or immediately after the irradiation of the wafer with the laser beam.

[0041] The physical modification can be achieved, for example, by introducing local mechanical stresses or changing the electrical conductivity in the section. The etchability of the wafer can depend on mechanical stresses or electrical conductivity.

[0042] The physical modification can be produced, for example, by phase segregation in non-single-component crystals. The formation of the physical modification can be independent of whether two solid phases form or one or more substances escape from the wafer in gaseous form.

[0043] The physical modification can be produced near the surface of the wafer.

[0044] Etchability can be understood as chemical reactivity or solubility towards acids and / or bases. Through physical modification, the etchability of the wafer in the relevant section can be increased or decreased.

[0045] The etch rate can be defined as the speed at which material is removed from a wafer surface during an etching process. Consequently, an etch depth can be set for a given etching process through physical modification.

[0046] The physical modification can be performed to prepare the wafer for etching. The physical modification can act as either masking or unmasking of the wafer. In other words, by performing the physical modification, the wafer can be masked or unmasked. Unmasking can refer to unmasked areas or sections.

[0047] Due to the physical modification, the wafer in that section may have a higher etchability, in particular etch rate, or a lower etchability, in particular etch rate, than in the rest of the section which is free from the physical modification.

[0048] The lithography process may include: etching the wafer. The wafer etching may be performed, in particular immediately, after the physical modification has been created. The wafer etching may include etching the area with the physical modification and simultaneously etching the remaining area, which is free of the physical modification. The creation of the physical modification and the etching of the wafer, in particular the physical modification, may be performed without the use of a photoresist and / or a developer solution.

[0049] The electrical component can be fabricated by multiple or multi-stage etching of the wafer. At least one etching step of the multiple etching process can involve etching the section with the physical modification and simultaneously etching the remaining section, which is free of the physical modification. This etching can be performed without the use of photoresist and / or developer. The remaining etching steps of the multiple etching process can be performed using photoresist and / or developer. In other words, at least one etching step can be performed without the use of photoresist and developer, and the remaining etching steps can be performed using photoresist and developer. It is also conceivable that more or all etching steps of the multiple etching process can be performed without the use of photoresist and / or developer.The electrical component can be manufactured entirely without the use of a photoresist and / or developer solution. However, it is also conceivable that the electronic component could be produced by a single etching of the wafer without the use of a photoresist and / or developer solution.

[0050] In a further development of the lithography process, the physical modification is achieved by removing material from the wafer in the relevant section. The etchability of the wafer can depend on this material removal.

[0051] For example, the wafer can have a semiconductor substrate and a coating, with the semiconductor substrate being coated by means of the coating. Removing material from the wafer can involve removing the coating. The coating and the semiconductor substrate can differ in their etchability.

[0052] For example, the coating cannot be dissolved with an acid and / or base, while the semiconductor substrate can be dissolved with an acid and / or base. By removing the coating in that section, the wafer can be etched in that section.

[0053] In a further development of the lithography process, the physical modification is achieved by forming microcracks in the section. This allows the physical modification to be produced independently of the presence or absence of a coating. The microcracks increase the surface area exposed to an acid or base during an etching process. The etchability of the wafer can depend on the presence or absence of these microcracks.

[0054] Microcracks can also refer to the formation of so-called pinholes. A microcrack can have a length ranging from 0.5 pm to 1 mm.

[0055] In a further development of the lithography process, the physical modification is achieved through a phase transformation of the wafer material in the relevant section. This allows different phases of the wafer material to be used to modify the etchability. The etchability of the wafer can thus be dependent on a specific phase of the wafer material.

[0056] The etchability can be changed by altering the phase of the wafer material. The phase of the wafer material after laser irradiation can depend on the pulse duration, intensity, and / or frequency of the laser beam.

[0057] The material phase can be, for example, amorphous, crystalline, or semi-crystalline. Semi-crystalline can be understood to mean that the wafer material exhibits nanocrystallites, microcrystallites, or macrocrystallites.

[0058] Phase transformation can, for example, be a change between a crystalline and an amorphous state of the wafer material. For instance, the wafer material may be in a crystalline state before laser irradiation and in an amorphous state in the irradiated area after laser irradiation, or vice versa.

[0059] In a further development of the lithography process, the physical modification is achieved by melting the wafer material in the relevant section. This melting allows for the alteration of a phase within the wafer material and / or a ratio, such as a mixing ratio, of the material components from which the wafer is formed.

[0060] Melting can lead to the enrichment or reduction of a material component in the section via diffusion. The etchability can depend on the concentration of the material component.

[0061] After the section is irradiated with the laser beam to melt the material, the material can solidify. The material may have a different phase after solidification than before melting.

[0062] In a further development of the lithography process, the physical modification is achieved by outgassing a material component of the wafer in the section. This allows the concentration of the material components in the section to be changed. The etchability of the wafer can then depend on the concentration of the material component.

[0063] For example, the wafer may contain hydrogen, and irradiation with a laser beam can cause the hydrogen to outgas from the area. This can reduce the hydrogen concentration in that area. The etchability can depend on the concentration of the material components. Outgassing can be understood as the release of a material component from the wafer. This outgassing can change the density of free or saturated electron bonds.

[0064] In a further development of the lithography process, the laser pulses of the laser beam have a pulse duration of less than or equal to 100 ps. Advantageously, such a pulse duration allows for a particularly small heat-affected zone, making the physical modification highly precise. The laser beam can preferably be an ultrashort pulse laser beam.

[0065] In a further development of the lithography process, the physical modification is formed from a plurality of physical sub-modifications. These physical sub-modifications can differ from one another. For example, they can differ in size. The physical type modifications can also be arranged side by side to form the physical modification.

[0066] The laser beam can be used to create the physical partial modifications sequentially. In particular, the laser beam can be guided across the wafer to create the physical modifications, producing the partial modifications one after the other.

[0067] In a further development of the lithography process, each physical sub-modification has a size in the range of 200 nm to 2 pm, particularly 250 nm to 800 nm. The lithography process can be especially advantageous for producing a physical sub-modification of such a size. Each physical sub-modification can be the smallest unit of the physical modification. The physical sub-modification can have a size of 350 nm or 450 nm.

[0068] The size can be the length, width, or depth of the physical part modification. The size can also be the diameter of the physical part modification.

[0069] In a further development of the lithography process, each physical sub-modification has a size with a value ranging from half a wavelength of the laser beam to twice the wavelength of the laser beam. Such sizes can be produced with high quality using the lithography process. In a further development of the lithography process, each physical sub-modification has a size, in particular a diameter, that is smaller than the diameter of a laser spot created by the laser beam when it strikes the wafer during irradiation of the section.

[0070] The laser spot can be referred to as a laser patch. Any physical partial modification can be produced if the laser beam in an area of ​​the laser spot has an intensity that exceeds a threshold value for producing the physical partial modification.

[0071] If the laser beam has a Gaussian intensity distribution, any physical partial modification produced with the laser beam can have a diameter that is less than or equal to half the diameter of the laser spot.

[0072] In a further development of the lithography process, the lithography process, after generating the laser beam and before irradiating the section with the laser beam, includes: shaping the laser beam using a mask. The laser beam can be locally switched off using the mask, so that the section is completely irradiated with the laser beam. The laser beam can be shaped using the mask in such a way that the wafer is irradiated with a pattern defined by the mask.

[0073] In a further development of the lithography process, the wafer comprises a semiconductor substrate and a layer. The layer is arranged on the semiconductor substrate. The physical modification is produced within the layer. This allows the lithography process to be applied to semiconductor substrates made of a material in which the physical modification cannot be produced using a laser beam.

[0074] The layer can be a surface layer of the wafer. In other words, a surface section of the wafer can be formed by the layer.

[0075] The layer can serve to create the physical modification. The layer can be specifically designed and intended for this purpose. In particular, the physical modification can only be created within the layer.

[0076] The layer can have a thickness ranging from 5 nm to 500 nm. The layer can be composed of pure silicon or doped silicon. Alternatively, the layer can be composed of SiN or SiC>2. Preferably, the layer can be composed of silicon nitride (SiSl). Advantageously, the physical modification can be produced with particular precision in a silicon-containing layer. In other words, a silicon-containing layer is particularly well-suited for producing the physical modification.

[0077] The layer may contain a gas, particularly hydrogen. The physical modification can be achieved by exgassing the gas from the layer using a laser beam.

[0078] For example, a phase of the layer before irradiation with the laser beam can be amorphous, crystalline or semi-crystalline.

[0079] The layer can be a sector of the semiconductor substrate that has been modified by a surface modification, for example by implantation, oxidation, application of surface charges, planar crystallization or amorphization.

[0080] The layer can be a coating on the semiconductor substrate. The semiconductor substrate can be coated with the layer, in particular a coating. The coating can be produced by sputtering, magnetron sputtering, thermal evaporation, electron beam evaporation, ion beam deposition, or molecular beam epitaxy. The lithography process can include: coating the semiconductor substrate with the layer by sputtering, magnetron sputtering, thermal evaporation, electron beam evaporation, ion beam deposition, or molecular beam epitaxy.

[0081] An arrangement according to the invention is designed for fabricating an electrical component in a wafer. The arrangement comprises the wafer, a laser beam source, and a focusing device. The etchability, in particular the etch rate, of the wafer can be changed by irradiation with a pulsed laser beam. The laser beam source is configured to generate the pulsed laser beam. The laser beam is configured to physically modify the wafer. The focusing device is configured to focus the pulsed laser beam onto a section of the wafer for the purpose of changing the etchability, in particular the etch rate, of the wafer by creating a physical modification in that section. The laser pulses of the pulsed laser beam have a pulse duration of less than or equal to 100 ns. The arrangement can be configured and specifically designed to perform a previously described lithography process.The previously given description of the lithography process can apply to identical or functionally equivalent features of the arrangement and / or vice versa.

[0082] The focusing device can include a lens and / or a concave mirror. The laser beam can be guided through the lens or over the concave mirror for the purpose of focusing the laser beam onto the wafer.

[0083] The focusing device can incorporate F-theta optics, in particular an F-theta lens. The F-theta optics allow the laser beam to be focused onto a flat surface of the section. Distortions that occur during the deflection of the laser beam, for example by a galvo scanner or a polygon scanner, can be corrected by the F-theta optics.

[0084] The arrangement may include a deflection device for guiding the laser beam across the wafer. The deflection device may include a galvo scanner or a polygon scanner for guiding the laser beam across the wafer. The galvo scanner may include at least one galvanometer mirror. The polygon scanner may include at least one polygon mirror or mirror galvanometer. The laser beam may be guided across the galvo scanner or the polygon scanner for the purpose of directing the laser beam onto the wafer and / or for the purpose of guiding the laser beam across the wafer.

[0085] The arrangement may include a beam shaping device for shaping the laser beam. Beam shaping can be understood as changing the intensity distribution of the laser beam. For example, the beam shaping device may be configured to change, or specifically shape, a Gaussian intensity distribution of the laser beam into a flat-top intensity distribution. The beam shaping device may include a diffractive optical element or a microlens array for shaping the laser beam. Alternatively, the beam shaping device may include a MEMS or a spatial light modulator (SLM) for shaping the laser beam.

[0086] The arrangement may include a control unit. The control unit may be configured as an electronic computing unit, in particular as a computer and / or as a microcontroller. The control unit may be configured to control the laser beam source for the purpose of generating the laser beam. The control unit may be configured to control the deflection device for the purpose of guiding the laser beam across the wafer.

[0087] One use according to the invention relates to the use of a previously described lithography process and / or the use of a previously described arrangement for manufacturing the electrical component, in particular an integrated circuit, preferably a microchip.

[0088] Further advantages and advantageous embodiments of the invention can be seen from the figures, their description, and the claims. All features disclosed in the figures, their description, and the claims can be essential to the invention, both individually and in any combination. The figures show:

[0089] Fig. 1 shows a schematic representation of an arrangement for manufacturing an electrical component in a wafer,

[0090] Fig. 2 is a schematic top view of the wafer of Fig. 1 during irradiation of a section of the wafer with a laser beam.

[0091] Fig. 3 shows a schematic sectional view of the wafer along a section line Ill-Ill according to Fig. 2.

[0092] Figures 4 to 6 each show a schematic sectional view of a further embodiment of the wafer according to Figure 3.

[0093] Fig. 7 shows a schematic representation of another embodiment of the arrangement for manufacturing an electrical component in a wafer, and

[0094] Fig. 8 is a schematic top view of the wafer from Fig. 7.

[0095] Fig. 1 shows an arrangement 10 for fabricating an electrical component in a wafer 12. The arrangement 10 is configured to perform a lithography process for fabricating the electrical component in the wafer 12. The electrical component is a microchip. The arrangement 10 is used for fabricating the microchip. In an alternative embodiment not shown, the electrical component can be a microelectromechanical system.

[0096] Arrangement 10 includes wafer 12. Wafer 12 has a semiconductor substrate 14 and a layer 16.

[0097] The semiconductor substrate 14 is silicon. Preferably, the semiconductor substrate 14 has a silicon content of at least 85% by weight, and in particular 95% by weight. The wafer 12 is formed as a rectangular plate with a thickness in the range of 0.5 mm to 2 mm.

[0098] The semiconductor substrate 14 is coated with layer 16. Layer 16 can also be referred to as a coating. The coating 16 forms a section of the surface of the wafer 12.

[0099] The coating 16 was produced using a magnetron sputtering process. The coating is made of SiÜ2. The coating 16 has a thickness ranging from 10 nm to 400 nm.

[0100] In an alternative embodiment not shown, the layer can be produced by surface modification of the semiconductor substrate. Surface modification of the semiconductor substrate can be achieved, for example, by implantation, oxidation, application of surface charges, local crystallization, or local amorphization.

[0101] The arrangement 10 has a laser beam source 18. The laser beam source 18 is a solid-state laser. The laser beam source 18 serves to generate a laser beam 20.

[0102] The laser beam 20 is a pulsed laser beam 20. In other words, the laser beam 20 is formed from a plurality of laser pulses. The pulse duration of the laser pulses has a value in the range of 100 fs to 100 ns, preferably 150 fs to 100 ps. The pulse energy of the laser pulses can have a value in the range of 1 nJ to 10 mJ, preferably 250 nJ to 1 pJ. The laser beam 20 has a wavelength with a value in the range of 1 pm to 1.2 pm. The laser beam 20 has an average power with a value in the range of 5 W (watts) to 10 kW. The laser beam 20 has a Gaussian intensity distribution. The arrangement 10 has a deflection device 22 for guiding the laser beam 20 across the wafer 12. The laser beam 20 is guided by the deflection device 22. The deflection device 22 has two galvo scanners 24, 26. Each galvo scanner 24, 26 is designed as a galvanometer mirror or mirror galvanometer.In other words, each galvo scanner 24, 26 has a mirror for deflecting the laser beam 20 and a galvanometer drive for moving the mirror.

[0103] The arrangement 10 has a focusing device 28. The focusing device 28 serves to focus the laser beam 20 onto the wafer 12. The focusing device 28 is a lens through which the laser beam 20 passes. The lens is configured as an F-theta lens.

[0104] After passing through the focusing device 28, the laser beam 20 strikes the wafer 12. Specifically, the laser beam 20 strikes the coating 16. Irradiating the coating 16 with the laser beam 20 alters its etchability, particularly its etch rate. This change in etchability is achieved by creating a physical modification using the laser beam 20.

[0105] The arrangement 10 has a control unit 30 for controlling the laser beam source 18 and the two galvo scanners 24, 26. The control unit 30 can include an electronic computing unit, in particular a computer and / or a microcontroller. The control unit 30 is predefined with a target section of the wafer 12 in which the physical modification is to be produced. For producing the physical modification, the control unit 30 can control the laser beam source 18 and the two galvo scanners 24, 26 based on the target section such that the physical modification is produced within a section of the wafer 12 by means of the laser beam 20.

[0106] Fig. 2 shows the wafer 12 with a view towards the coating 16 during the production of the physical modification 32 within the section 34 of the wafer 12. The production of the physical modification 32 is carried out by irradiating the section 34 with the laser beam 20.

[0107] Fig. 2 shows that not the entire section 34 yet exhibits the physical modification 32. The control unit 30 controls the laser beam source 18 and the two galvo scanners 24, 26 such that the laser beam 20 successively produces partial physical modifications 36 within the section 34 of the wafer 12. The partial physical modifications 36 together constitute the physical modification 32. The control unit 30 controls the laser beam source 18 and the two galvo scanners 24, 26 until a partial physical modification 36 has been produced at every point within the section 34.

[0108] Fig. 2 shows that the laser beam 20 strikes the coating 16, forming a laser spot 38 on the coating 16. The diameter of the laser spot 38 can be equal to the beam diameter of the laser beam 20 at the location of the coating 16. The laser beam 20 generates a fluence or energy density at the location of the laser spot 38 with a value in the range of 0.01 J / cm². 2 up to 1 J / cm 2 causes.

[0109] Each physical partial modification 36 is produced in a region 40 within the laser spot 38 if the laser beam 20 in the region 40 has an intensity that exceeds a threshold value for producing the physical partial modification 36. Due to the Gaussian intensity distribution of the laser beam 20, the region 40 has a circular shape, and the diameter 42 of the region 40 is smaller than the diameter 44 of the laser spot 38. Therefore, the diameter 42 of the region 40 and the diameter of the physical partial modification 36 are the same, which is why the same reference symbol is used for both diameters.

[0110] The diameter 42 of region 40, and thus the diameter 42 of physical sub-modification 36, has a value equal to half the wavelength of the laser beam 20. In other words, the diameter 42 of physical sub-modification 36 can have a value in the range of 500 nm to 600 nm.

[0111] Fig. 3 shows a schematic sectional view of the wafer 12 along section line III-III according to Fig. 2. Fig. 3 shows that the creation of a physical partial modification 36 is achieved by removing material from the coating 16. In other words, the coating 16 is removed in section 34 by the laser beam 20. The physical modification is formed by the absence of material from the coating 16.

[0112] The laser pulses have a pulse duration such that the irradiation of section 34 for the production of a physical partial modification 36 takes place with a duration that is shorter than the duration for conducting heat and the duration for mass transport in the wafer 12. This prevents thermal heating of the coating 16 and / or the semiconductor substrate 14 by the laser beam 20.

[0113] The physical modification 32 alters the etchability, in particular the etch rate, of the wafer 12 in section 34. The physical modification 32 acts as a demasking of the wafer 12. As a result, the wafer 12 can have at least one section that is masked by the absence of the physical modification and section 34 in which the wafer 12 is either demasking or unmasked. This gives the wafer 12 sections that differ in their etch rates, allowing microchip structures to be etched into the wafer 12. In particular, the wafer 12 can be etched directly, preferably without any further intermediate steps, after the physical modification 32 has been applied.

[0114] Figures 4 to 6 each show a further embodiment of the wafer 12 of Figure 3, whereby the same reference numerals are used for identical and functionally equivalent elements and reference can be made to the above explanations of the embodiment of Figure 3, so that for each further embodiment only the existing differences are essentially discussed.

[0115] Fig. 4 shows that the production of each physical part modification 36 is achieved by the formation of microcracks 46 in the area 40. Due to the microcracks 46, the surface area of ​​the coating 16 in the section 34 is increased, allowing an acid or base to dissolve the section 34 more quickly than a section of the wafer 12 that is free of microcracks. Each microcrack 46 can have a length ranging from 1 pm to 1 mm.

[0116] Fig. 5 shows that the coating 16 contains hydrogen. In other words, hydrogen is incorporated into the coating 16. Each physical partial modification 36 is produced by outgassing the hydrogen from region 40. In other words, due to the irradiation of the wafer 12 with the laser beam 20, the hydrogen concentration in region 40 is reduced by outgassing. The physical partial modification 36 is formed by the reduction of the hydrogen concentration in region 40. Since the etchability of the coating 16 depends on the hydrogen concentration in the coating 16, the etchability in region 40 can be changed by reducing the hydrogen. Fig. 6 shows that each physical partial modification 36 is produced by a phase transformation of the coating 16 material in region 40. The coating 16 material has a semi-crystalline state.By irradiating the coating 16 with the laser beam 20, the material of the coating 16 in region 40 is melted. After irradiation with the laser beam 20, the molten material solidifies. After solidification, the molten material of the coating 16 exhibits an amorphous state. This changes the phase of the material of the coating 16 in region 40 from a semi-crystalline state to an amorphous state. Since the etchability of the coating 16 depends on the phase of the material of the coating 16, the etchability in region 40 can be changed by altering the phase of the material of the coating 16.

[0117] The embodiments shown in Figures 3 to 6 each demonstrate that the physical modification 32 is produced in the coating 16. However, it is also conceivable that the physical modification 32 is additionally produced in the semiconductor substrate 14. In an alternative embodiment not shown, the wafer may not have a coating, and the physical modification can be produced in the semiconductor substrate.

[0118] Fig. 7 shows a further embodiment of the arrangement 10 of Fig. 1, wherein identical and functionally equivalent elements use the same reference numerals and in this respect reference can be made to the above explanations of the embodiment of Fig. 1, so that for the further embodiment of Fig. 7 essentially only the existing differences are discussed.

[0119] The arrangement 10 has a beam shaping device 48 for changing the intensity distribution of the laser beam 20. Before passing through the beam shaping device 48, the laser beam 20 has a Gaussian intensity distribution, and after passing through the beam shaping device 48, it has a flat-top intensity distribution. The beam shaping device 48 has a diffractive optical element through which the laser beam 20 passes in order to change its intensity distribution from the Gaussian to the flat-top.

[0120] The arrangement 10 has a mask 50 through which the laser beam 20 passes. The mask 50 locally blocks the laser beam 20. After passing through the mask 50, the laser beam 20 strikes the coating 16. The mask 50 shapes the laser beam 20 such that the section 34, in which the physical modification 32 is to be produced, is completely or fully irradiated with the laser beam. This eliminates the need to guide the laser beam 20 across the wafer 12, which is why the arrangement 10 of Fig. 7 does not include galvo scanners. Fig. 8 shows the wafer 12, looking towards the coating 16, after the wafer 12 has been irradiated with the laser beam and thus after the physical modification 32 has been produced within the section 34.

Claims

Patent claims 1. Lithography method for manufacturing an electrical component in a wafer (12), wherein the lithography method comprises: Generating a laser beam (20), wherein the laser beam (20) is a pulsed laser beam, wherein the laser pulses of the laser beam (20) have a pulse duration of less than or equal to 100 ns, and Producing a physical modification (32) in a section (34) of the wafer (12) by irradiating the section (34) with the laser beam (20), wherein the physical modification (32) changes an etchability, in particular an etch rate, of the wafer (12) in the section (34).

2. Lithography method according to claim 1, wherein the physical modification (32) is produced by removing material from the wafer (12).

3. Lithography process according to one of the preceding claims, wherein the physical modification (32) is produced by forming microcracks (46).

4. Lithography process according to one of the preceding claims, wherein the physical modification (32) is produced by a phase transformation of the wafer material (12).

5. Lithography process according to one of the preceding claims, wherein the physical modification (32) is produced by melting the material of the wafer (12).

6. Lithography process according to one of the preceding claims, wherein the physical modification (32) is produced by outgassing a material component of the wafer (12).

7. Lithography method according to one of the preceding claims, wherein the laser pulses of the laser beam (20) have a pulse duration of less than or equal to 100 ps.

8. Lithography process according to one of the preceding claims, wherein the physical modification (32) is formed from a plurality of physical partial modifications (36).

9. Lithography method according to claim 8, wherein each physical part modification (36) has a size (42) with a value in a range of 200 nm to 2 pm, in particular 250 nm to 450 pm.

10. Lithography method according to claim 8 or 9, wherein each physical part modification (36) has a size (42) with a value in a range from half a wavelength of the laser beam (20) to twice the wavelength of the laser beam (20).

11. Lithography method according to any one of claims 8 to 10 above, wherein each physical part modification (36) has a size (42) that is smaller than a diameter (44) of a laser spot (38) produced by the laser beam (20) during irradiation of the section (34) upon impact on the wafer (12).

12. Lithography method according to one of the preceding claims, wherein the lithography method comprises, after generating the laser beam (20) and before irradiating the section (34) with the laser beam (20): shaping the laser beam (20) by means of a mask (50).

13. Lithography method according to one of the preceding claims, wherein the wafer (12) has a semiconductor substrate (14) and a layer (16), wherein the layer (16) is arranged on the semiconductor substrate (14), wherein the physical modification (32) is produced in the layer (16).

14. Arrangement (10) for manufacturing an electrical component in a wafer (12), wherein the arrangement (10) comprises: the wafer (12) whose etchability, in particular etch rate, can be changed by irradiation with a pulsed laser beam (20), a laser beam source (18) for generating the pulsed laser beam (20) configured to physically modify the wafer (12), and a focusing device (28) for focusing the pulsed laser beam (20) onto a section (34) of the wafer (12) for the purpose of changing an etchability, in particular an etch rate, of the wafer (12) by making a physical modification (32) in the section (34), - wherein the laser pulses of the pulsed laser beam (20) have a pulse duration of less than or equal to 100 ns.

15. Use of a lithography process according to any one of the preceding claims 1 to 13 and / or use of an arrangement (10) according to claim 14 for manufacturing the electrical component.

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