Apparatus and method for laser processing of substrates

Abstract

An apparatus for drilling holes in a substrate is provided. The apparatus includes a laser system configured to apply a laser beam to the substrate to remove material from a set of areas on the substrate by sequencing and directing the laser beam to predetermined locations corresponding to the set of areas on the substrate. The apparatus includes a ventilation system configured to generate a fluid flow along one or both sides of the substrate. The apparatus controls the laser beam such that the laser beam is sequentially positioned according to a first laser beam movement direction and a second laser beam movement direction.

Description

[Technical Field]

[0001] Embodiments of the present disclosure relate to apparatus and methods for laser machining of substrates. More particularly, embodiments described herein relate to apparatus and methods for efficient and accurate laser machining of substrates, particularly for forming via holes, such as crystalline silicon (c-Si) substrates or polymer composite substrates. [Background technology]

[0002] In fields such as next-generation PCB (printed circuit board) manufacturing, display manufacturing, or solar cell manufacturing, there is an increasing demand for mass processing of substrates such as crystalline silicon (c-Si) substrates, particularly c-Si wafers, or substrates including polymer-based build-up films such as Ajinomoto build-up films. To achieve high throughput and high precision, substrates can be processed using laser processing methods, particularly laser drilling and laser cutting.

[0003] Challenges arise when processing substrates at high speeds and therefore with high laser energy and high precision. When hit by the laser light, the substrate can heat up in undesirable places and even melt locally. In such a situation, high precision can no longer be guaranteed. Even worse, in such a situation, continued laser exposure with unchanged parameters can lead to poor drilling efficiency and quality. Furthermore, debris generated by the drilling process can further interfere with accurate processing and reduce the precision of the laser processing. For cost reasons, substrates are usually thin and fragile, making them particularly prone to damage and breakage, further increasing the difficulty of the machining process.

[0004] In view of the foregoing, a new method and apparatus for laser processing of substrates that overcomes at least some of the problems in the art would be beneficial. Summary of the Invention

[0005] According to one aspect, an apparatus for drilling holes in a substrate is provided. The apparatus includes a laser system configured to apply a laser beam to the substrate to remove material from a set of areas on the substrate by sequentially directing the laser beam to predetermined locations corresponding to the set of areas on the substrate. The sequencing defines an order in which each area receives the laser beam. The apparatus further includes a ventilation system configured to generate a fluid flow along one or both sides of the substrate. The fluid flow is directed in a fluid flow direction. The apparatus further includes a controller configured to sequentially position the laser beam according to a first laser beam movement direction and a second laser beam movement direction, and to repeatedly direct the laser beam to each location corresponding to the set of areas at least three times. After each time an area from the set of areas receives the laser beam, at least half of the areas that received the laser beam are allowed to cool for at least 50 milliseconds. The angle between the first laser beam movement direction and the fluid flow direction is defined as q1, and the angle between the second laser beam movement direction and the fluid flow direction is defined as q2. - cos q1 and cos q2 are both less than or equal to 0, or - q1 and q2 are each greater than 20° and less than 340°, or - Either q1 or q2 is less than 20° or greater than 340°, and the movement of the laser beam is controlled so that the area to which the laser beam is applied in sequence is separated by two or more areas from the area that was previously hit by the laser beam in the sequence.

[0006] According to one aspect, a method for drilling holes in a substrate is provided. The method includes applying a laser beam to the substrate by sequentially directing the laser beam to predetermined locations corresponding to a set of areas on the substrate. The sequencing defines an order in which each area receives the laser beam. The laser beam removes material from the set of areas. The method further includes generating a fluid flow along one or both sides of the substrate while applying the laser beam to the substrate. The fluid flow is directed in a fluid flow direction. Sequentially applying the laser beam includes sequentially positioning the laser beam according to a first laser beam movement direction and a second laser beam movement direction, and repeatedly directing the laser beam to each location corresponding to the set of areas at least three times. After each time an area from the set of areas is subjected to the laser beam, at least half of the areas exposed to the laser beam are allowed to cool for at least 50 milliseconds. The angle between the first laser beam movement direction and the fluid flow direction is defined as q1, and the angle between the second laser beam movement direction and the fluid flow direction is defined as q2. - cos q1 and cos q2 are both less than or equal to 0, or - q1 and q2 are each greater than 20° and less than 340°, or - q1 or q2 is less than 20° or greater than 340°, and the movement of the laser beam is controlled so that the area to which the laser beam is applied in sequence is separated by two or more areas from the area that was previously hit by the laser beam in the sequence.

[0007] According to aspects, the methods and apparatus for drilling disclosed herein comprise one or two first laser beam movement directions and one or two second laser beam movement directions, in which the laser is not moved in another direction during the drilling process except for auxiliary actions such as, but not limited to, moving the laser to a start position or directing the laser back to a rest position.

[0008] According to an embodiment, the direction of laser beam movement is not the same as the fluid flow direction except when the laser beam movement is controlled such that immediately before the laser beam movement, the area impinged by the laser beam is separated from the area impinged by the laser beam by two or more zones, particularly six or more zones. Additionally, according to an embodiment, the angle between any direction of laser beam movement and the fluid flow direction during the drilling process is not less than 20° or greater than 340° except when the laser beam movement is controlled such that immediately after the laser beam movement, the area impinged by the laser beam is separated from the area impinged by the laser beam by two or more zones, particularly six or more zones.

[0009] Embodiments are also directed to apparatus for performing the disclosed methods, including apparatus parts for performing each of the above method aspects. These method aspects may be performed by hardware components, a computer programmed by appropriate software, any combination of the two, or in other ways. Moreover, embodiments according to the present disclosure are also directed to methods for operating the described apparatus. Methods for operating the described apparatus include method aspects for performing all of the functions of the apparatus.

[0010] The present disclosure, briefly summarized above, can be described in more detail with reference to embodiments so that the above-listed features of the present disclosure can be understood in detail. The accompanying drawings relate to embodiments of the present disclosure and are described below. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an apparatus for laser processing of a substrate according to embodiments described herein; [Figure 2] 1 is a schematic diagram of an apparatus for laser processing of a substrate according to embodiments described herein; [Figure 3] FIG. 1 shows a schematic set of areas to be treated and the movement of the laser beam between the areas relative to the fluid flow. [Figure 4] FIG. 1 shows a schematic set of areas to be treated and the movement of the laser beam between the areas relative to the fluid flow. [Figure 5] FIG. 1 shows a schematic set of areas to be treated and the movement of the laser beam between the areas relative to the fluid flow. [Figure 6] FIG. 1 shows a schematic set of areas to be treated and the movement of the laser beam between the areas relative to the fluid flow. [Figure 7] FIG. 1 shows a schematic set of areas to be treated and the movement of the laser beam between the areas relative to the fluid flow. [Figure 8] FIG. 10 shows angles q1 and q2 between the laser beam movement direction and the fluid flow direction. DETAILED DESCRIPTION OF THE INVENTION

[0012] Reference will now be made in detail to various embodiments of the present disclosure, one or more examples of which are illustrated in the figures. In the following description of the figures, like reference numerals refer to like components. Generally, only differences with respect to individual embodiments will be described. Each example is provided as an explanation of the disclosure and is not meant as a limitation of the disclosure. Furthermore, features illustrated or described as part of one embodiment may be used on or in conjunction with other embodiments to yield still further embodiments. The description is intended to include such modifications and variations.

[0013] Applications of the present disclosure relate particularly to the production of any type of multilayer electronic assembly, such as printed circuit boards (PCBs), semiconductor packages, solar or photovoltaic cells, display devices such as LCD, OLED or microLED based screens, or any type of device requiring high precision handling of c-Si wafers or substrates, including porous polymer thin films.

[0014] According to one embodiment, the substrate may be a silicon-based substrate, such as a crystalline silicon (c-Si) substrate or wafer. The substrate may include structures, functional layers, or devices disposed thereon, such as semiconductor devices, dielectric layers, doped layers, metal layers, etc., for example, for providing electrical connections, or other structures commonly known in semiconductor manufacturing. The substrate may include a polymer-based layer, such as a dielectric film. The dielectric film may be a polymer film, such as a polymer composite film. The polymer-based layer may include a film, such as an Ajinomoto build-up film. The substrate may be disposed on a support structure, such as a polymer film disposed on a silicon-based support structure, and drilling may include drilling through the polymer film without extending to the underlying silicon-based support structure.

[0015] As understood herein, a hole may refer to a through hole that passes through the entire thickness of a substrate. Alternatively, or in addition, as understood herein, a hole may refer to a blind hole. In particular, as understood herein, a hole may refer to an array of holes. A hole may be configured to form a via in a substrate. A hole may be configured to provide a component therein. A hole may be advantageously configured to modify the mechanical, electrical, or thermal properties of a substrate. A hole may be configured to allow for subsequent manufacturing operations that include the hole.

[0016] According to aspects of the present disclosure, so-called percussion drilling, i.e., drilling each hole with only one action, such as one laser exposure, laser projection, or "shot," is not envisioned. Rather, it is proposed to drill each hole in an iterative process. As used herein, an iterative process can be understood as each hole being repeatedly hit with a laser beam, referred to herein as a "shot," each time for a certain period of time. Each shot aims to remove material from the area where the laser beam strikes. In terms of substrate thickness, the removed material corresponds, for example, to at most 25%, more particularly at most 20%, or at most 15% of the thickness of the substrate at the location of the area where the laser beam strikes.

[0017] According to one aspect, the drilling process includes a laser system configured to apply a laser beam to a substrate to remove material from a set of areas on the substrate. The laser system may include a laser light source including a laser emitter. The laser light source may include an ultraviolet (UV) or infrared laser, such as a solid-state laser, a diode-pumped laser, a pulsed laser, and / or a carbon dioxide laser. The laser light source may be selected according to the substrate material, for example, according to advantageous embodiments, so that the wavelength of the laser beam is highly absorbed in the substrate material. Specifically, an infrared laser with a wavelength greater than 1,000 nm may be selected for a c-Si substrate, and a UV laser with a wavelength less than 400 nm may be selected for a polymer substrate, particularly an ABF-based substrate.

[0018] According to one aspect, the laser system may further include an optical assembly that focuses the laser beam to form a laser beam. The laser beam may be a narrow beam with high spatial coherence. The laser beam may generally be conical and / or focused on the substrate to provide a narrow exposure area corresponding in size to, for example, the diameter of the hole to be drilled; for example, the narrow exposure area may have a size of 5% to 90%, such as 20% to 50% or less than 40% of the diameter of the hole to be drilled. According to one embodiment, the area receiving the laser beam may have a shape with a circumference, and the laser beam may be directed to a predetermined location corresponding to the circumference of the area.

[0019] According to one embodiment, the laser system may include a laser beam directing assembly. The laser beam directing assembly may include one or more laser beam directing mirrors. The surface of the laser beam directing mirror may be polygonal. The laser beam directing mirror may be movable, particularly rotatable. For example, a laser beam may be directed onto a first area of a substrate to be drilled by being directed onto a first surface of the laser beam directing mirror. Once the laser beam directing mirror is moved, rotated, or pivoted, the laser beam may strike a second surface of the laser beam directing mirror and jump to a second area of the substrate to be drilled.

[0020] According to one aspect, the drilling process typically includes predetermined locations on the substrate corresponding to a set of areas to be drilled in a predetermined order, such as an order defining the locations corresponding to the set of areas on the substrate to be drilled. An apparatus for drilling these areas may include a controller. The controller may be configured to control movement of the laser beam to irradiate the laser only on the areas to be drilled in the order. Areas between the areas not designed to be drilled are not subjected to the laser beam. This may be done, for example, by providing a controllable laser beam directing mirror, such as a mirror included in a galvanometer assembly, particularly a two-axis galvanometer assembly, such as a two-axis scanning galvo system.

[0021] According to one embodiment, the laser beam directing mirror can have a reflective surface that reflects and directs the laser beam to a desired location on the substrate. The desired location on the substrate can be a first location, and the laser beam directing mirror can be controlled to direct the laser beam to the first location and then to a second location, which can also be the desired location on the substrate. The transition between the first and second locations can be fast and can include jumps of the laser beam between the first and second locations. In particular, the laser beam directing mirror can be configured to enable fast transitions between multiple positions, for example, the transition from the first location to the second location can occur at a frequency of 0.1 to 100 kHz, 0.5 to 50 kHz, or 1 to 30 kHz.

[0022] Additionally or alternatively, according to one embodiment, the laser beam directing mirror may be configured to continuously move the laser beam over the substrate, particularly over the areas of the substrate that include the set of areas to be drilled. Continuous movement may include various speeds. The laser beam may be continuous. For example, the laser beam may be repeatedly blocked by a shutter to prevent the laser from entering areas between the areas to be drilled. The shutter may be controlled by a controller as described herein. The shutter may be controlled to drill predetermined locations on the substrate corresponding to the set of areas. In particular, the shutter may be controlled to prevent areas between the areas to be drilled from being exposed to the laser beam. Instead of or in addition to a shutter, the laser beam may be pulsed, for example, by operating the shutter as described above and / or by providing a laser light source configured for pulsed operation, such as a pulsed laser. According to one embodiment, the laser light source configured for pulsed operation may include a laser light source configured for Q-switching, i.e., a laser light source including a Q-switch, such as an active or passive Q-switch, and / or an acousto-optic modulator for pulsing the laser.

[0023] According to one aspect, the general embodiments described herein can generate an array of holes in a substrate, the array consisting of n rows and m columns, where n and m are integers. This results in a total of m x n holes being drilled. In further embodiments, the array can include not drilling a set of holes in the n m substrate. The array can have "missing" holes or sections by design. The array can include several subarrays, which can be defined as an n m array. According to embodiments, complex patterns can be formed based on multiple subarrays, where the subarrays are arrays as described herein.

[0024] According to one embodiment, the devices and methods described herein are configured to process a substrate, i.e., process areas on the substrate including at least 1,000 areas, particularly at least 10,000 areas, or at least 100,000 areas, to generate a set of holes.

[0025] According to one embodiment, a substrate may be created with one array of holes. According to one embodiment, a substrate may be created with several arrays of holes. The array of holes may include a set of areas. A substrate may be processed to include several arrays of holes, i.e., several sets of areas, such as at least two sets of areas, at least four sets of areas, at least six sets of areas, or at least ten sets of areas. According to embodiments of the present disclosure, a first array of holes may be drilled until complete, and then a second array of holes may be drilled until complete (or similarly if there are more arrays, e.g., at least four arrays).

[0026] Generating several arrays of holes may include generating an array of holes in a first section of the substrate, as described herein, and then moving the substrate relative to the apparatus to generate a next array of holes in a second section of the substrate. According to embodiments, the apparatus may include a substrate support, such as a susceptor, a holder, a work table, such as a two-axis work table or a rotary work table configured to feed the substrate into the apparatus and move the substrate relative to the apparatus, for example, after a set of zones has been processed. According to embodiments, during processing, the substrate may be fixed rather than moved, and the laser system may be repositioned to move relative to the substrate or the apparatus.

[0027] It may be particularly advantageous to subsequently generate several arrays of holes when the laser system's processable area or "field of view" is smaller than the total substrate area to be processed. In one example, the laser system may have a "field of view" that corresponds to the area the laser system can process, with a set of areas within the field of view. The field of view may be at least 50 mm x 50 mm, at least 100 mm x 100 mm, at least 165 mm x 165 mm, or even at least 250 mm x 250 mm.

[0028] According to one aspect, in an embodiment, the laser beam is directed at each position corresponding to the area to be drilled at least three times, or even at least five times, or at least ten times. The drilling process can be specifically designed so that the number of shots is set to obtain a hole of a predetermined depth in the substrate. In particular, the predetermined depth can be the thickness of the substrate. In this case, the drilling process is designed so that the number of shots is preset to generate a through hole.

[0029] According to one aspect, in an embodiment, the number of times the laser is directed to a set of areas is a function of the thickness of the substrate, which depends on the substrate material; i.e., the number of pulses or shots exposing a thin substrate may be fewer than that of a thick substrate. The number of times the laser is directed to a set of areas may be greater than one-tenth of the substrate thickness in micrometers. In a first example, the laser is repeatedly directed to an area of a silicon substrate having a thickness of 100 μm or less at least five times. In a second example, the laser is repeatedly directed to an area of a silicon substrate having a thickness of 1000 μm or more at least 200 times. In a third example, the laser is repeatedly directed to an area of a polymer film substrate or polymer composite film substrate having a thickness of 100 μm or less at least 20 times. In a fourth example, the laser is repeatedly directed to an area of a polymer film substrate or polymer composite film substrate having a thickness of 1000 μm or more at least 400 times. In this example, a through hole is obtained.

[0030] According to one aspect, after each time an area from a set of areas is subjected to the laser beam, at least half of the areas that received the laser beam are allowed to cool for at least 50 milliseconds before being subjected to the laser beam again. The areas are allowed to cool for at least 60 milliseconds, at least 80 milliseconds, at least 100 milliseconds, or even at least 500 milliseconds. According to an embodiment, each area that receives the laser beam is allowed to cool. Advantageously, the area is allowed to cool while another area is being processed; in particular, a set of areas can be processed sequentially while individual areas in the set are allowed to cool.

[0031] According to one aspect, in an embodiment, the controller configured to control the method and laser beam for drilling holes is designed so that the size (e.g., measured as diameter) and / or depth of all holes in the substrate are equal. "Equal" in this context may be understood as theoretically equal, and in practice includes deviations due to slightly different material properties, e.g., of the substrate.

[0032] By repeatedly directing the laser beam at each location corresponding to a set of areas several times and allowing the areas to cool after receiving the laser beam, the uniformity and positioning of the resulting holes may be improved. Additionally, localized heating of the substrate may be avoided, and greater uniformity may be achieved between holes at the edges of the set of areas and holes in the center of the set of areas.

[0033] It has been experimentally observed that, in some cases, debris generated during the application of a laser beam to an area can, under certain conditions, interfere with the drilling of adjacent areas, for example, by scattering or absorbing the laser beam in an undesirable manner. This can limit the achievable speed or quality of the drilling operation. Such undesirable effects can be overcome by aspects of the apparatus and methods described in more detail herein.

[0034] According to one aspect, a ventilation system is provided. The ventilation system is configured to generate a fluid flow along one or both sides of a substrate. The one or both sides of the substrate typically include a surface of the substrate, and more particularly, the surface of the substrate includes a set of perforated regions. The fluid flow is directed in a fluid flow direction. The fluid flow can be unidirectional, i.e., the fluid can flow in substantially the same direction for each region of the set of regions.

[0035] According to one aspect, the fluid flow may include a gas such as air, an inert gas, or a mixture thereof. The gas may be selected depending on the characteristics of the substrate or the laser beam. In one example, the gas may be oxygen-free to prevent oxidation or combustion of the substrate or debris, or to prevent ozone generation when using a low-wavelength laser beam. The gas may be dried to reduce infrared absorption of the gas, particularly when an infrared laser beam is used. The gas may include nitrogen. The gas may include a noble gas such as helium or argon. The ventilation system may include a circulation system for recirculating the fluid flow.

[0036] According to one aspect, the apparatus may include an enclosure. The enclosure may enclose the laser system, the substrate support, and / or the substrate. The enclosure may include ports for loading and unloading the substrate, such as a load lock chamber or a door. The enclosure may be configured to provide fluid flow and to maintain the fluid composition, i.e., to seal gases as described above. The enclosure may include a gas inlet and a gas outlet. The gas inlet and gas outlet may be in fluid communication with a ventilation system, particularly to provide fluid flow to the interior of the enclosure. The enclosure may form part of the ventilation system.

[0037] According to one embodiment, the fluid flow may be laminar or substantially laminar. Laminar flow in the context of the present disclosure may be defined as a fluid flowing substantially without turbulent characteristics. Laminar flow in the context of the present disclosure may further be understood as a flow in which there is substantially no horizontal mixing between volumes containing the flow, such as a volume of the flow defined by the spatial dimensions defining the surface of the substrate, or the spacing between each of a set of regions along all spatial dimensions, particularly a volume of the fluid flow adjacent to the surface of the substrate, particularly a volume including a space up to 2 mm above the surface of the substrate. The fluid flow may include a portion of non-laminar flow in regions not adjacent to the surface of the substrate.

[0038] The flow may have a flow rate, i.e., velocity, of greater than 1 meter per second (m / s), greater than 2 m / s, such as 2-5 m / s, or greater than 5 m / s, such as greater than 10 m / s, in a volume encompassing 1 mm to 2 mm of space above one or both sides of the substrate. Fluid flow rates may be expressed in cubic feet per minute (CFM), and equipment designed to process 100 mm x 100 mm substrates typically has a fluid flow rate of at least 100 CFM, specifically greater than 200 CFM.

[0039] According to one embodiment, the fluid flow carries away at least a portion of the debris generated when the laser beam is applied to the area. The debris may include a solid or gas, or a mixture with substantially gaseous properties such as aerosols or vapors, such as ionized gases, suspended particles, and / or substrate material evaporated from the substrate during laser exposure. Carrying away the debris may include carrying the debris away before applying the laser beam to the area again. Carrying away the debris may include transporting the debris in the direction of the fluid flow, possibly across other areas of the set of areas. As described in more detail herein, it may be advantageous to not apply the laser beam to an area while debris from other areas is present on that area.

[0040] According to one embodiment, the laser beam described herein generally has a first movement direction and a second movement direction. The movement direction can be understood as the direction of movement between a first area and a second area that subsequently receives the laser beam. The laser beam can be inactive during the movement that defines the movement direction; that is, when moving from a first position to a second position according to the movement direction, the laser beam may cross an area that is not intended to be hit by the laser beam and may be turned off, for example, by a shutter. The laser beam movement direction can be defined relative to the surface of the substrate, i.e., the movement direction can be along a two-dimensional plane formed by the surface of the substrate on which the set of areas to be perforated is located. Similarly, the fluid flow direction can be the fluid flow direction relative to the plane defined by the substrate.

[0041] According to one aspect, the first and second moving directions may be laser beam moving directions between each of the set of regions. The regions, particularly those defining the first laser beam moving direction, may be adjacent. The first and second moving directions may be different, e.g., have an angle along a plane defined by the substrate therebetween. In a typical embodiment, the angle between the first and second moving directions may be +90° and / or −90°. Regions within a set of regions may be adjacent if they can be reached without crossing other regions within the set. Regions within a set of regions may be adjacent if they have the closest spacing within the set. Adjacent in the context of the present disclosure should not be understood to involve contact between the regions; i.e., adjacent regions may be physically spaced apart.

[0042] According to an aspect, the first movement direction can be changed at least once, and in embodiments, multiple times, during the drilling process. Specifically, the first movement direction can be a specific direction relative to the first numbered area and an opposite direction relative to the second numbered area. According to an aspect, the second movement direction can be changed at least once, and in embodiments, multiple times, during the drilling process. Specifically, the second movement direction can be a specific direction relative to the first numbered area and an opposite direction relative to the second numbered area.

[0043] According to one embodiment, the movement direction, particularly the second movement direction, can be a laser beam movement direction between non-adjacent areas of the set of areas under certain conditions, as defined in detail below. Each area of the set of areas can be non-adjacent if it cannot be reached without directly or indirectly crossing another area of the set of areas. Each area of the set of areas can be non-adjacent if it has an area that is closer to one of the non-adjacent areas than to other adjacent and / or non-adjacent areas with a space between them.

[0044] Areas including dense areas can be non-adjacent if the laser beam movement from one area to the next can reach another area before the next area. Areas can be non-adjacent if the laser beam movement is such that after the laser moves through the laser beam movement, the area that receives the laser beam in the sequence is separated from the area that received the laser beam earlier in the sequence by two or more, six or more, particularly at least eleven or more, areas.

[0045] According to one aspect, the angle between the first laser beam movement direction and the fluid flow direction is defined as q1, and the angle between the second laser beam movement direction and the fluid flow direction is defined as q2. For example, if the laser beam movement direction is parallel to the fluid flow, the angle is 0°. If the laser beam movement direction is opposite to the fluid flow, the angle is 180°. If the laser beam movement direction is perpendicular to the fluid flow, the angle is 90° or 270°. In embodiments, the apparatus and methods described herein may be mirror-symmetric with respect to the definitions of q1 and q2, such that the angles 90° and 270° may be equivalent and / or the value space may be defined as an angle range from 0° to 180°. By defining the order of the areas to be exposed to the laser beam and / or performing the drilling according to a defined relationship between q1 and q2, debris from each area may be carried away so as not to interfere with the next area to be exposed to the laser beam. Advantageous embodiments, including preferred ranges and examples for q1 and q2, are described in more detail below.

[0046] Referring now to the figures, the general aspects discussed above will be explained in more detail and with reference to embodiments.

[0047] FIG. 1 is a schematic diagram of an apparatus according to one embodiment of the present disclosure. A laser 100 emits a laser beam 120. The laser beam may be emitted directly onto a substrate 110. Generally, without being limited to this mechanism, an actuator (not shown) may be provided to move the laser. The movement may include translational and / or rotational movement. In the embodiment of FIG. 1, as shown, the laser beam is directed to a beam director 105. The beam director 105 may include, among other things, one or more mirrors and / or one or more lenses for guiding the laser beam, such as causing the laser beam to follow a predetermined sequence. Additionally or alternatively, the beam director may include a shutter. The shutter is typically controlled by a controller to block the laser beam during a blocking time and allow the laser beam to pass during an irradiation time. Specifically, the shutter may block the laser beam to prevent it from hitting areas outside the area of the substrate to be drilled.

[0048] According to an embodiment, the shutter can be controlled to block the laser beam between two shots. For example, a first shot can be applied to the substrate at a location on the substrate corresponding to the area to be drilled. The laser beam is then blocked by the shutter and directed to the second area to be drilled, after which the shutter unblocks the laser beam after a period of time. As used herein, controlling the shutter can coincide with controlling the laser beam movement.

[0049] The substrate 110 may rest on a substrate support 115. The substrate support may be movable. In other embodiments, the substrate support may be fixed. The apparatus of the present disclosure may include a substrate movement device, such as a gripper, for positioning the substrate on the substrate support. The substrate support may include a vacuum suction unit configured to apply a vacuum to the bottom of the substrate to ensure that the substrate remains completely stationary as it is laser machined.

[0050] The apparatus of the present disclosure may further include a ventilation system 125. As shown, the ventilation system generates a fluid flow 15. The fluid flow 15 discussed in this disclosure is typically oriented parallel to the substrate support surface and / or the substrate. It is assumed that the fluid flow generates a flow 15 that carries or carries away debris generated during laser processing. In particular, the present disclosure provides the benefit of controlling laser movement being designed in relation to the fluid flow direction to optimize the drilling process and ensure that debris generated during drilling of one area does not adversely affect drilling of another area, such as a nearby or adjacent area.

[0051] As exemplarily shown with respect to FIG. 2 , the apparatus may include a housing. A ventilation system 125 may be provided outside the housing. An intake opening 130, such as the channel shown in FIG. 2 , may be provided to guide the fluid flow into the housing. A substrate may be provided inside the housing. The housing may further include an outlet opening 135 to allow the fluid flow to exit the housing. In an alternative embodiment, the ventilation system is provided inside the housing. Moreover, in an embodiment that may be combined with any of the previously described embodiments, a fluid flow suction system may be provided. The fluid flow suction system may be configured to suction the fluid flow provided by the ventilation system. In this manner, a closed fluid flow may be provided that may be particularly optimized for removing debris and the like from the substrate. The outlet opening 135 may be connected to the ventilation system 125 by a fluid transport system, such as a circulation system, to enable recirculation of the fluid. A filter may be provided to filter debris from the fluid after it exits the outlet opening 135.

[0052] According to one embodiment, the order in which the laser beam is directed at the substrate to remove material from each area of the set of areas is defined to satisfy one of the following three conditions: 1) Both cos q1 and cos q2 are less than or equal to 0. In other words, both q1 and q2 are in the range of 90° to 270°. The first or second laser beam movement direction relative to the fluid flow direction is within this range; i.e., the movement direction can be perpendicular to the fluid flow, or can have a movement component opposite to the fluid flow direction in addition to the perpendicular movement. In one example, this condition is met when one of the first laser beam movement direction and the second laser beam movement direction is opposite to the fluid flow direction and / or when one of the first laser beam movement direction and the second laser beam movement direction is perpendicular to the fluid flow direction. 2) Each of q1 and q2 is greater than 20° and less than 340°; or 3) q1 or q2 is less than 20° or greater than 340°, and the movement of the laser beam is controlled so that the area sequentially subjected to the laser beam is separated from the area previously subjected to the laser beam by two or more areas. In this condition, the laser beam movement direction has a movement component that coincides with the flow direction. Adjacent areas may be affected by debris from the area previously subjected to the laser beam, while distant areas remain unaffected. In an advantageous example, this condition is selected for only one of the first laser beam movement direction or the second laser beam movement direction. In an advantageous example, this condition is selected only if an alternative movement direction according to, for example, condition 1) or 2) is not available, or if movement according to condition 3) enables some subsequent operation according to condition 1) or 2).

[0053] Below, some example sequences for laser movement are discussed with reference to the figures.

[0054] As exemplarily shown in Figures 3-7, circles 10 represent areas where drilling is envisioned. For clarity of the figures, only a few of these circles are explicitly designated by the reference numeral 10. Flow provided by the present disclosure has a direction indicated by arrow 15 in the figures. While the first laser beam movement direction is generally represented by a solid line and the second laser beam movement direction is generally represented by a dotted line, this should not be considered limiting, and exceptions from this convention will become apparent in the examples below. According to a general aspect that may be combined with or included in all embodiments described herein, the first laser beam movement direction may be the direction of movement of the laser beam between adjacent areas, and / or the second laser beam movement direction may be the direction of movement of the laser beam between non-adjacent areas.

[0055] Referring now to FIG. 3 , a set of areas on a substrate is shown according to one embodiment. For ease of illustration, the set of areas shown in the following figures is smaller compared to the application of the present disclosure. The set of areas is shown as a 4×8 array. Each area in the set of areas is subjected to the laser beam multiple times according to a shot sequence. A fluid flow 15 having a direction indicated by an arrow is provided. The sequence may begin, for example, with the lower-left area 20. Subsequent areas are sequentially subjected to the laser beam along a first laser beam movement direction represented by line 1, i.e., a solid line having a 90° angle q1 with respect to the fluid flow direction, thus satisfying condition 1).

[0056] When the laser beam reaches the lower right section, it is moved in a second laser beam movement direction (dotted line) to reach the leftmost section of the next line. The second laser beam movement direction 2 has an angle q2 of 260° with respect to the fluid flow direction, thus satisfying condition 1).

[0057] These operations are repeated until the top right section 25 is reached, after which the second laser beam movement direction 2 is adjusted to move the laser beam back to the bottom left section 20. The second laser beam movement direction 2 for this movement is at 300° with respect to the fluid flow direction q2, so neither condition 1) nor 2) is satisfied. However, the top right section is several sections away from the bottom left section, so condition 3) is satisfied.

[0058] Referring now to Figure 4, a set of zones according to one embodiment is shown. The set of zones may be the set of zones described in relation to Figure 3, and therefore only differences in laser beam positioning are described. The sequence may start, for example, with the bottom right zone 20. The following zones (shown in the bottom line) are sequentially subjected to the laser beam along a line, i.e., a first laser beam movement direction 1, represented by a solid line having an angle q1 of 270° relative to the fluid flow direction, thus satisfying condition 1).

[0059] When the laser beam reaches the bottom left area, it is moved in a second laser beam movement direction 2 to reach the leftmost area of the next line. The second laser beam movement direction is opposite to the fluid flow direction and therefore has an angle q1 of 180° with respect to the fluid flow direction, thus satisfying condition 1.

[0060] Subsequent areas along the line are then subjected to the laser beam as before, but the first laser beam movement direction 1 is adjusted to move in the opposite direction relative to the previous first laser movement direction, represented as a solid line having an angle q1 of 90° with respect to the fluid flow direction, thus satisfying condition 1).

[0061] These operations are repeated until the upper right area 25 is reached, after which the second laser beam movement direction is adjusted to return the laser beam to the lower right area. The second laser beam movement direction 2 for this movement is the same as the fluid flow direction, so q2 is 0°. For such a situation, neither conditions 1) nor 2) are satisfied. However, the upper right area 25 is several areas away from the lower right area 20, so condition 3) is satisfied. Note that the transition from area 25 to area 20 is represented as a curve in FIG. 4 for reasons of clarity only; i.e., the transition could be performed in line with a straight line between areas 25 and 20. However, in practice, the zone in which the laser is located after this movement in the second laser beam movement direction along the angle q2=0° (designated with reference number 20 in FIG. 4) is at least 10 zones, more specifically at least 20 zones, away from the zone before this movement, so that debris from drilling in the zone designated with reference number 25 does not pose a risk to further drilling operations. In addition, the transition between zones 25 and 20 can be performed slowly or with a delay to ensure that debris generated by the processing of zone 25 is swept away by the fluid flow and does not interfere with the processing of zone 20.

[0062] Referring now to FIG. 5, a set of areas according to one embodiment is shown. The set of areas may be the set of areas described in connection with FIG. 3 or FIG. 4. Only differences with respect to the embodiment described in connection with FIG. 3 or FIG. 4 will be discussed. The sequence begins with processing area 20, the upper left corner of the set of areas. After the first line of areas is processed, the laser beam is moved in a second laser beam movement direction toward the leftmost area of the next line. The angle q2 is 250°, thus satisfying condition 2). Moreover, the leftmost area is several areas away from the previous area, thus satisfying condition 3). The transition from area 25 back to area 20 has a second laser beam movement direction with an angle q2 of 150°, thus satisfying condition 1).

[0063] Referring now to Figure 6, a set of zones according to one embodiment is shown. The set of zones may be the set of zones described in connection with Figures 3-5, and therefore only differences in laser beam positioning are described. The sequence may start, for example, with the bottom right zone 20. The following four zones are sequentially subjected to the laser beam along a line, i.e., a first laser beam movement direction represented by a solid line having an angle q1 of 180° with respect to the fluid flow direction, thus satisfying condition 1).

[0064] When the laser beam reaches the upper right section, it is moved in a second laser beam movement direction to reach the bottom section of the next line. The second laser beam movement direction has an angle q2 of 345° with respect to the fluid flow direction, so neither condition 1) nor 2) is satisfied. However, the upper right section 25 is several sections away from the lower right section 20, so condition 3) is satisfied. In practice, the distance is at least 10 sections, specifically 21 sections or more, or even 31 sections or more.

[0065] These operations are repeated until the upper left section 25 is reached, after which the second laser beam movement direction is adjusted to return the laser beam to the lower right section 20. The angle q2 of this movement is 60°, thus satisfying condition 2). Moreover, the leftmost section is several sections away from the previous section, thus satisfying condition 3).

[0066] Referring now to FIG. 7, a set of areas according to one embodiment is shown. The set of areas is presented as a 4×6 array. The processing operation starts from the bottom line area 20 in the array and moves outward along a first direction having an angle q1 of 270° until the outermost area is reached. The first movement direction of the laser beam satisfies condition 1). The laser beam is then moved in a 90° laser beam movement direction q2 to reach an area in the line of areas adjacent to the starting area 20 in the array. Note that the movement along the second direction is represented as a curve in FIG. 7 for ease of understanding only; i.e., the movement could be performed in line with a straight line. Therefore, the second movement direction of the laser beam satisfies condition 1).

[0067] After the transition, the direction of the first laser beam movement direction q1 is adjusted to 90° and the areas of the line of areas in the array are processed until the outermost area is reached. Then, the transition to the next line of areas in the array of areas is performed with the second laser beam movement direction having an angle q2 of 110°, thus fulfilling condition 1).

[0068] These operations are repeated until the top right section 25 is reached, after which the second laser beam movement direction is adjusted to return the laser beam to the bottom left section 20. The second laser beam movement direction for this movement is 300° relative to the fluid flow direction q2, so neither condition 1) nor 2) is satisfied. However, the top right section is several sections away from the bottom left section, so condition 3) is satisfied.

[0069] By directing the laser beam according to the described embodiments, particularly those that satisfy any of the conditions 1) to 3) described above, rapid processing of a set of areas can be achieved while simultaneously allowing each area of the set of areas to cool for at least 50 milliseconds while the next area is processed according to a predetermined sequence. Moreover, debris generated during the laser operation is carried away by the fluid flow in the fluid flow direction, while each laser shot is unaffected by the debris. As a result, waiting times between laser shots are eliminated while maintaining a high processing quality not obtainable with known processes.

[0070] Figure 8 is intended to illustrate angles q1 and q2. Arrow 15 represents the fluid flow direction, and additional arrows between each section 20 may represent the first laser beam movement direction or the second laser beam movement direction. The angle between the first or second laser beam movement direction (represented as "1 / 2" in Figure 8) and the fluid flow direction is represented by 200, which in the example of Figure 8 is 270°.

[0071] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. 1. An apparatus for drilling holes in a substrate, comprising: a laser system configured to apply a laser beam to the substrate to remove material from a set of areas on the substrate by directing the laser beam in an ordered manner to predetermined locations corresponding to the set of areas on the substrate, the ordering defining an order in which the areas receive the laser beam; a ventilation system configured to generate a fluid flow along one or both sides of the substrate, the fluid flow being directed in a fluid flow direction; a controller configured to control the laser beam such that the laser beam is sequentially positioned according to a first laser beam movement direction and a second laser beam movement direction; the laser beam is repeatedly directed to respective positions corresponding to the set of areas, an angle between the first laser beam movement direction and the fluid flow direction is defined as q1, and an angle between the second laser beam movement direction and the fluid flow direction is defined as q2; wherein either q1 or q2 is less than 20° or greater than 340°, and wherein movement of the laser beam is controlled such that the areas receiving the laser beam in the sequence are separated by two or more areas from an area previously receiving the laser beam in the sequence.

2. 2. The apparatus of claim 1, wherein the movement of the second laser is such that the area that receives the laser beam in the sequence after the laser has moved by the second movement is separated by six or more areas, in particular at least eleven or more areas, from the area that received the laser beam earlier in the sequence.

3. The apparatus of claim 1 or 2, wherein the area has a shape that includes a perimeter, and the laser beam is directed to a predetermined position of the area that corresponds to the perimeter.

4. 4. The apparatus of claim 1, wherein one of the first laser beam movement direction and the second laser beam movement direction is opposite to the fluid flow direction and / or one of the first laser beam movement direction and the second laser beam movement direction is perpendicular to the fluid flow direction.

5. 5. Apparatus according to any one of claims 1 to 4, wherein the set of regions comprises at least 1,000 regions, particularly at least 10,000 regions, more particularly at least 100,000 regions.

6. 6. Apparatus according to any one of claims 1 to 5, wherein the fluid flow comprises one or more from the group consisting of an inert gas, in particular helium or argon, and nitrogen.

7. 7. The apparatus of claim 1, wherein the fluid flow is unidirectional, laminar, and the flow velocity exceeds 1 m / s in a volume comprising a space of 1 mm to 2 mm above the one or both sides of the substrate.

8. The device according to claim 1 , wherein the substrate is a silicon substrate or a substrate comprising a polymer film or a polymer composite film.

9. 9. The apparatus of claim 1, further comprising a housing containing a gas inlet and a gas outlet.

10. A method for drilling holes in a substrate, applying a laser beam to the substrate by directing the laser beam in an ordered manner to predetermined locations corresponding to a set of areas on the substrate, the ordering defining an order in which the areas receive the laser beam, and the laser beam removing material from the set of areas; generating a fluid flow along one or both sides of the substrate while applying the laser beam to the substrate, the fluid flow being directed in a fluid flow direction; sequencing the application of the laser beams, the sequencing including sequentially positioning the laser beams according to a first laser beam movement direction and a second laser beam movement direction; the laser beam is repeatedly directed to respective positions corresponding to the set of areas, an angle between the first laser beam movement direction and the fluid flow direction is defined as q1, and an angle between the second laser beam movement direction and the fluid flow direction is defined as q2; wherein either q1 or q2 is less than 20° or greater than 340°, and movement of the laser beam is controlled such that the areas to which the laser beams are applied in the sequence are separated by two or more areas from the area that was previously subjected to the laser beam in the sequence.

11. The method of claim 10 , further comprising carrying away with the fluid flow at least a portion of debris generated when the laser beam strikes an area of the set of areas.

12. 12. The method of claim 10 or 11, comprising carrying away with the fluid flow at least a portion of one of the following groups: ionized gas, aerosol, or vaporized substrate material produced when the laser beam strikes an area of the set of areas.

13. 13. An apparatus or method according to any one of claims 1 to 12, wherein the substrate comprises one or more sets of areas.

14. 14. An apparatus or method according to any one of claims 1 to 13, wherein the number of times the laser is directed at the set of areas is a function of the thickness of the substrate, which is dependent on the substrate material, and wherein the number of times is greater than one tenth of the thickness of the substrate in micrometers.

15. 15. An apparatus or method according to any one of claims 1 to 14, wherein each of the areas subjected to the laser beam is allowed to cool for at least 50 milliseconds, or at least half of the areas subjected to the laser beam are allowed to cool for at least 50-100 milliseconds or at least 100 milliseconds.

16. An apparatus for drilling holes in a substrate, comprising: a laser system configured to apply a laser beam to the substrate to remove material from a set of areas on the substrate by directing the laser beam in an ordered manner to predetermined locations corresponding to the set of areas on the substrate, the ordering defining an order in which the areas receive the laser beam; a ventilation system configured to generate a fluid flow along one or both sides of the substrate, the fluid flow being directed in a fluid flow direction; a filter for collecting debris from the fluid flow, the fluid flow passing through the filter being provided to the back of the ventilation system for circulation; a controller configured to control the laser beam such that the laser beam is sequentially positioned according to a first laser beam movement direction and a second laser beam movement direction; the laser beam is repeatedly directed to respective positions corresponding to the set of areas, an angle between the first laser beam movement direction and the fluid flow direction is defined as q1, and an angle between the second laser beam movement direction and the fluid flow direction is defined as q2; cos q1 and cos q2 are both less than or equal to 0, or Each of q1 and q2 is greater than 20° and less than 340°, or wherein either q1 or q2 is less than 20° or greater than 340°, and wherein movement of the laser beam is controlled such that the areas receiving the laser beam in the sequence are separated by two or more areas from an area previously receiving the laser beam in the sequence.

17. An apparatus as described in claim 1 or 16, wherein the laser beam is repeatedly directed at each position corresponding to the set of areas at least three times, and each time an area from the set of areas is exposed to the laser beam, at least half of the areas exposed to the laser beam are then allowed to cool for at least 50 milliseconds.

18. The method of claim 10, wherein the laser beam is repeatedly directed at each location corresponding to the set of areas at least three times, and each time an area from the set of areas is exposed to the laser beam, at least half of the areas exposed to the laser beam are then allowed to cool for at least 50 milliseconds.

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