Device with a glass substrate carrier for processing a substrate and method for its production

Abstract

Device for treating and / or processing a particularly transparent or transmissive substrate (2) by means of laser radiation (3) with a laser, a suction (14) and / or vacuum source and a substrate carrier (1) made of glass, with a first upper surface serving as a substrate support (4) and a lower surface (5) facing away from it, wherein the substrate support (4) of the substrate carrier (1) has a structure (6) produced by modifications in the substrate carrier (1) and by material removal by the action of an etching medium in the respective area of ​​the modifications in the substrate carrier (1), wherein the structure (6) has several adjacent and conical recesses (7) merging into one another, and wherein at least one recess (7) is designed as a through-opening (8) of the substrate carrier (1) between the substrate support (4) and the lower surface (5) and several conical recesses (7) are designed as depressions (9),wherein the extraction (14) and / or negative pressure source is assigned to the recesses (7).

Description

The invention relates to a device with a glass substrate carrier for processing a substrate, having a first upper surface serving as a substrate support and a lower surface facing away from it, wherein the substrate support and / or the lower surface of the substrate carrier has a structured surface. The invention further relates to a method for producing the substrate carrier by introducing modifications and subsequently applying an etching medium, thereby creating conical recesses. A process for the precision machining of glass using laser-induced deep etching, known as LIDE (Laser Induced Deep Etching), is used to create deep structures such as through holes or micro-cuts. LIDE technology makes it possible, for the first time, to achieve modifications across the entire thickness of the glass using single laser pulses. In deep etching, known for example from WO 2014 / 161 534 A2, a transparent material, such as a glass plate, is modified by means of a laser pulse or pulse train over an elongated area along the beam axis, often over the entire thickness of the transparent material, and is then anisotropically etched in a wet chemical etching bath. WO 2016 / 041 544 A1 discloses a method for creating a recess in a plate-shaped glass substrate using laser radiation, wherein, due to the action of an etching medium, anisotropic material removal occurs in the modified areas of the glass substrate through successive etching. EP 4 011 846 A1 discloses a method for structuring a glass element in which filament-shaped modifications are generated by means of ultrashort laser pulses and subsequently widened by etching to form recesses, channels or through-holes, in particular where the conicity angle of the resulting structures can be adjusted. US patent 2009 / 0013724A1 describes a glass processing method in which areas modified by laser irradiation are created in a glass plate and then selectively etched to form, in particular, conical holes, through-holes or grooves. DE 10 2005 006 838 A1 relates to a device for testing thin elements, in particular wafers or single substrates, in which a substrate support of high stiffness, preferably made of glass, is used to support and fix the substrate. In DE 10 2020 134 451 A1 a method for processing or pre-cutting a planar substrate is described, in which the substrate rests on a substrate support and is held in the area of ​​the processing zone by a force directed towards the substrate support, such as negative pressure. US Patent 8 173 038 B2 discloses methods and systems for forming microstructures in glass substrates by laser ablation, wherein, in particular, conical cavities, depressions or regularly arranged microstructures can be produced by targeted laser guidance. DE 10 2017 106 372 A1 discloses a method for processing a workpiece using laser radiation, in which, in addition to separation contours, material weaknesses or predetermined breaking points are also created that are not completely cut through and are subsequently treated by etching. From EP 3 967 442 A1 a method for producing a technical mask from a plate-shaped substrate is known, in which openings are created by laser-induced deep etching and connecting bridges prevent premature detachment of the separated areas. DE 10 2015 101 440 A1 relates to a semiconductor component package comprising an electronic component, an electrical intermediate connection and at least one further semiconductor chip located below the intermediate connection. WO 2016 / 083 508 A1 describes a substrate holding device with a carrier plate and a holding frame inserted into a recess, the device being intended in particular for the transport and processing of substrates, for example in vacuum processes. US 5 103 976 A describes a transport and storage tray for integrated circuits, especially PGA components, with a grid-like frame and support areas that hold the components in defined pockets. WO 2004 / 033 197 A2 describes a carrier for thin substrates in which a very thin substrate is detachably connected to a carrier substrate, in particular via a bonding material in the surface or edge area, to enable process-reliable handling. DE 10 2015 108 639 A1 discloses a composite of a glass support and a glass foil or a silicon wafer, wherein the surface of the glass support is structured so that the contact area is reduced and at least one cavity is formed between the support and the substrate. The object of the present invention is the production of a glass substrate carrier for processing a substrate by means of laser processing with a densely structured surface and partial permeability of the material to negative pressure. As preparatory measures, various modifications are introduced into the material to be used, for example, through several different focusing processes. In the first step, the ideal focus and power settings for generating openings, the so-called Through Glass Vias (TGVs), are determined and set. In the second step, a modification designated as Type I is created, which has a significantly weaker form and can typically be produced with about half the power required for TGVs. When choosing the settings, it is important to ensure that the resulting cone-shaped recesses on the top and bottom surfaces are the same size after a subsequent etching process. At a size of 50 µm, deviations of up to 4 µm between the top and bottom surfaces are acceptable. Subsequently, large panels measuring 300 x 300 mm² (preferably made of 500 µm material) are treated with a specific pattern. Low-power modifications are used for conical or cone-shaped cutouts, while higher-power modifications create perforations in the substrate carrier. These modifications have a pitch of 50 µm and are arranged in a hexagonal pattern. The spacing between the so-called "dice lines" is therefore 45 µm. A complete project file for this application is available and is always applied to a single 300 x 300 mm² panel. A blank produced in this way can be manufactured in advance and then stored. These blanks should be stored and marked separately to prevent confusion with other materials. A blank of this type is used to manufacture the substrate carrier. According to the respective specifications, the outer edge geometry is first modified by the device according to existing process parameters for TGVs and the material thickness of the plate-shaped material used for the substrate carrier. After modification, the sheet-like material is reduced by 10% of its thickness through wet chemical treatment. For 500 µm material, this means a reduction to 450 µm (typical process time: 50 minutes). In this state, the final contour can be cut from the 300 x 300 mm² panel. The sample with the final outer contour is then reduced by a further 10% of its thickness. In this state, all conical recesses are etched large enough that the cone shapes have grown into one another and no straight surfaces remain that are still reflective when the substrate is processed using electromagnetic radiation. With a suitable pattern on the substrate, a camera will only detect a black area. If light areas are still visible through the camera, which occur due to smooth glass surfaces, the etching process must be continued until the recesses are sufficiently large. The laser process parameters must be determined individually for each material and material thickness. Identical materials exhibit the same taper properties. Consequently, the overall process time of the wet-chemical treatment remains the same, but the distribution of time between several wet-chemical process steps can change. For alternative materials, the overall process time of the wet-chemical process also changes. Both the different etching rates and the differences in taper angle must be taken into account. The overall process time always depends on the time required until all Type I modifications have "grown" together and the surface no longer contains any flat areas. The proportion of the first wet-chemical process step, however, depends on the process time required to create a through-hole (TGV). By defining outer cut edges, any desired fit can be achieved for contact surfaces smaller than 300 × 300 mm². Key advantages of the device according to the invention with the substrate carrier are a minimal contact area between the substrate carrier and the substrate to be processed. The negative pressure that holds the substrate in place during processing can act on the substrate to be processed through the substrate carrier. The special shape of the substrate carrier ensures a suitable, large-area distribution of the negative pressure across the substrate. This is achieved through a combination of through-holes in the substrate carrier between the substrate surface and the underside, and several conical recesses in the form of cone-shaped depressions. The overlapping cone-shaped depressions create a volume beneath the applied substrate, which can distribute the negative pressure. The consistently angled shape of the substrate support increases its resistance to electromagnetic radiation during substrate processing. This makes it more difficult for the radiation to couple into the substrate and increases the durability of the substrate carrier under radiation exposure. Ablation of the substrate carrier by the radiation is prevented. The high angles of the substrate support surface ensure total internal reflection of the laser light. Back reflection of the laser light is prevented by scattering at the substrate carrier. Preferably, the microstructured surface of the substrate support for processing substrates made of a material transparent to electromagnetic radiation has conical or cone-shaped recesses with a diameter of 5-150 µm, with a spacing p<0.95xD, in particular p<0.89xD, so that the material to be processed, particularly in the area of ​​laser processing, rests on the substrate support over an area <1% of the substrate area, wherein the structuring can be limited to certain areas of the substrate support. In a further advantageous embodiment of the invention, a conductive coating, for example ITO, DLC, AZO, CNT (carbon nano tube) or a conductive metal coating such as in particular Cr, Ti, Mo, Au, Al on the top and / or bottom surface, serves to dissipate a static charge. Absorbing, reflective and / or transparent properties are advantageous in the coating, with the layer thickness preferably being less than 5 µm, in particular less than 3 µm or 1 µm. A particularly preferred application of the glass substrate carrier arises in laser processing methods for the substrate, wherein the substrate to be processed, in particular transparent, is in contact with the substrate carrier during processing with an average laser power of less than 500 W and / or a pulse energy of less than 500 µJ. Due to its structuring, the substrate carrier is also particularly suitable for fixing very thin substrates with a material thickness of less than 100 µm, especially less than 50 µm or 25 µm. When processing a transparent or transmissive substrate using electromagnetic radiation, the radiation passes through the substrate into the substrate layer, causing an absorbing substrate layer to be strongly heated or removed, and also resulting in undesirable effects on the substrate. To counteract this problem, the glass substrate carrier of the device according to the invention has a microstructured surface as a substrate support. This causes the radiation to scatter at the microstructured surface, largely preventing absorption. At the same time, this minimizes the contact area with the substrate by reducing the point contact. The through-holes serve to fix the negative pressure, whereby, according to a particularly practical design, structuring on both sides ensures an even distribution of the negative pressure and it is unnecessary to have an exact positioning in relation to a connection of a negative pressure source. The invention allows for various embodiments. To further illustrate its basic principle, one of these is shown in the drawing and described below. This embodiment is shown in a schematic representation: Fig. 1 shows a side view of a substrate carrier with recesses on one side; Fig. 2 shows a side view of a substrate carrier with recesses on both sides; Fig. 3 shows a side view of the substrate carrier shown in Fig. 1 during manufacturing; Fig. 4 shows the processing of a substrate on the substrate carrier shown in Fig. 1; Fig. 5 shows various phases of the etching process during the manufacture of the substrate carrier; Fig. 6 shows the substrate carrier after completion in a top view. A plate-shaped substrate carrier 1 of the device according to the invention and the method for its manufacture are explained in more detail below with reference to Figs. 1, 2, 3, 4, 5 to 6. The substrate carrier 1 consists of a transparent material, in particular glass, and serves to process a substrate 2, in particular a transparent or transmissive substrate, by means of laser radiation 3, for example a laser, which passes through the substrate 2 during processing and would therefore strongly heat or ablate a previously common, absorbing layer. The substrate carrier 1 has a top surface equipped with a substrate pad 4 and a bottom surface 5, wherein, according to the variant shown in Fig. 1, only the substrate pad 4 and, according to the variant shown in Fig. 2, both the substrate pad 4 and the bottom surface 5 of the substrate carrier 1 each have a structuring 6. To produce the substrate surface 4 and the structured underside 5 of the substrate carrier 1 shown in Fig. 2, the structures 6 are introduced by laser radiation 3 by first creating different modifications in the substrate carrier 1. Subsequently, conical recesses 7 are formed by the action of an etching medium and by successive etching due to anisotropic material removal in the respective area of ​​the modifications within the substrate carrier 1. As a result of the different modifications, several adjacent and / or overlapping conical recesses 7 are formed, which either form a through-opening 8 of the substrate carrier 1 between the substrate surface 4 and the underside 5 or as conical depressions 9 without penetrating the substrate carrier 1. Adjacent recesses 7 are separated from each other only by a wall surface 10, which extends to the common plane 11 of the point-like substrate support 4 thus created. The etching process is stopped when the surface or the wall surface 10 consists only of points that lie at least approximately in a common plane, preferably corresponding to the original glass surface. As can be seen in Fig. 5, the etching process initially creates the recesses 7 as cone-shaped depressions 9 without a through-opening 8. The etching process then continues until the thickness of the wall surfaces 10 is reduced to a minimum and is so thin that areas parallel to a principal plane of extension of the substrate 2 or orthogonal to the incident laser radiation 3 are at least largely removed. This simultaneously creates a flow-through connection between adjacent recesses 7 when the substrate 2 is in place, enabling the substrate 2 to be drawn in over a surface area and fixed by negative pressure. In the exemplary variant shown, the diameter D of the recesses 7 is approximately 30 µm to 150 µm, and the distance A between the recesses 7, measured between their respective centers, is approximately 20 µm to 140 µm, with the distance A being less than the diameter D.The depressions 9 therefore form a connected volume. In the variant shown in Fig. 2, several recesses 9, each with a through-opening 8, allow flow through them and are thus interconnected in a flow-conducting manner. A suction and / or vacuum opening 12 of a suction device 14 in a base 13 is assigned to several recesses 9, so that the desired suction can occur through the recesses 9 and the through-opening 8. Precise positioning of the through-opening 8 corresponding to the suction and / or vacuum opening 12 is unnecessary, thus eliminating the associated effort in use. REFERENCE MARK LIST 1 Substrate carrier 2 Substrate 3 Laser radiation 4 Substrate support 5 Underside 6 Structuring 7 Recess 8 Through opening 9 Indentation 10 Wall surface 11 Level 12 Extraction opening 13 Base 14 Extraction D Diameter A Distance

Claims

Device for treating and / or processing a particularly transparent or transmissive substrate (2) by means of laser radiation (3) with a laser, a suction (14) and / or vacuum source and a substrate carrier (1) made of glass, with a first upper surface serving as a substrate support (4) and a lower surface (5) facing away from it, wherein the substrate support (4) of the substrate carrier (1) has a structure (6) produced by modifications in the substrate carrier (1) and by material removal by the action of an etching medium in the respective area of ​​the modifications in the substrate carrier (1), wherein the structure (6) has several adjacent and conical recesses (7) merging into one another, and wherein at least one recess (7) is designed as a through-opening (8) of the substrate carrier (1) between the substrate support (4) and the lower surface (5) and several conical recesses (7) are designed as depressions (9),wherein the extraction (14) and / or negative pressure source is assigned to the recesses (7). Device according to claim 1, characterized in that adjacent recesses (7) are separated from each other by a common wall surface (10), wherein the wall surface (10) extends to a common plane (11) of the substrate support (4) and thus a partial and / or point-like substrate support (4) is created. Device according to claim 1 or 2, characterized in that a contact area of ​​the substrate support (4) with the substrate (2) is less than 1% of the areas bounded by a circumferential contour or the projected area of ​​the substrate support (4). Device according to one of the preceding claims, characterized in that at least individual recesses (9) with at least one recess (7) designed as a through-opening (8) are connected to each other in a flow-conducting or flow-through manner when the substrate (2) is placed on top. Device according to one of the preceding claims, characterized in that the recesses (7) designed as depressions (9) and the through-openings (8) in a plane (11) of the substrate support (4) have a matching size, area and / or geometry. Device according to one of the preceding claims, characterized in that the conical recesses (7) designed as depressions (9) have an opening angle of more than 30°, in particular between 50° and 70°, and the conical recesses (7) designed as through openings (8) have an opening angle of less than 30°. Device according to one of the preceding claims, characterized in that the substrate support (4) has at least sectionally a surface with electrical conductivity that is transparent or transmissive to the laser radiation (3), in particular produced by deposition on the substrate carrier (1). Device according to one of the preceding claims, characterized in that the underside (5) of the substrate carrier (1) has a structure (6) with in particular conical recesses (9) for flow-guiding connection of a suction and / or vacuum opening (12) with at least one recess (7) designed as a through-opening (8). Method for producing a plate-shaped substrate support (1) with a first upper surface serving as a substrate support (4) and a lower surface (5) facing away from it, wherein a structure (6) is produced on the substrate support (4) of the substrate support (1) by generating different modifications in the substrate support (1) by means of laser radiation (3) along a beam axis of the laser radiation (3) and subsequently conical recesses (7) by the action of an etching medium and by successive etching as a result of anisotropic material removal in the respective area of ​​the modifications in the substrate support (1),wherein the different modifications produce several adjacent and overlapping conical recesses (7) with at least one recess (7) as a through-opening (8) of the substrate support (1) between the substrate support (4) and the underside (5) and several conical recesses (7) as depressions (9) without openings, wherein the different modifications are produced such that during the etching process the recesses (7) are simultaneously widened until areas with a surface normal perpendicular to a plane of the substrate support (4) are removed and the recess (7) forming the through-opening (8) extends between the substrate support (4) and the underside (5). Method according to claim 9, characterized in that the recesses (7) designed as depressions (9) and the through-openings (8) are produced in a common etching process under identical etching conditions due to different modifications resulting from the laser radiation (3) with different focusing, pulse energy and / or power. Method according to claim 9 or 10, characterized in that the recesses (7) designed as depressions (9) are modified with a lower power and / or pulse energy of the laser radiation (3) than the recess (7) designed as a through-hole (8).

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