TW202140821A - Method and apparatus of performing laser ablation and method of depositing organic light emitting molecules - Google Patents

Abstract

Methods and apparatus for performing laser ablation are disclosed. In one arrangement, an ultraviolet laser beam is directed through a mask to image a portion of an ablation pattern defined by the mask onto a layer of material. The laser beam is scanned over the mask to sequentially image different portions of the ablation pattern onto different respective regions of the layer. A structure corresponding to the ablation pattern is thereby ablated into the layer. The laser beam comprises an ultra-fast pulsed laser beam having a pulse length of less than 20 picoseconds.

Description

Method and equipment for performing laser melting and method for depositing organic light-emitting molecules

The present invention relates to a method and equipment for performing laser ablation, and particularly relates to forming a fine metal mesh.

Fine metal meshes (FMMs) are used in the manufacture of organic light emitting diode (OLED) displays. Specifically, a fine metal mesh is used as a vapor deposition mask for organic light-emitting diodes in the manufacture of displays. The fine metal mesh defines where the organic light-emitting diode molecules are deposited on the display, and therefore ultimately determines the resolution of the organic light-emitting diode display.

The technologies currently used for the production of fine metal meshes include photolithography processes and electroforming processes. However, the cost of such a manufacturing process is high, and the resolution of an organic light emitting diode display using such a fine metal mesh is generally less than 600 pixels per inch (ppi). Modern applications (for example, mobile phones and virtual reality headsets) require higher resolution, such as 1000 pixels per inch or higher. It is difficult for the fine metal mesh manufactured by the photolithography process and the electroforming process to achieve such a high resolution.

Other conventional techniques for the production of fine metal meshes include splitting a single laser beam into multiple laser beams and scanning these laser beams across the surface of the substrate to form a fine metal mesh by melting. Such technology usually uses a femtosecond pulsed infrared laser. However, in order to obtain multiple laser beams, such a technique requires complicated projection optics. It is even difficult to scale up the scale of the technology to thousands of laser beams, so the speed of producing fine metal meshes in this way is limited. Such a system is capable of producing fine metal meshes with a critical size of 10 microns and a resolution of hundreds of dots per inch (dpi).

The embodiments of the present disclosure aim to at least partially solve one or more of the above-discussed problems and/or other problems.

According to an aspect of the present invention, there is provided a method for performing laser melting. The method includes: directing an ultraviolet laser beam through a mask to image a portion of the melting pattern defined by the mask onto a layer of material; and a scanning mine Beam to sequentially image different parts of the demelting pattern onto different areas of the layer on the mask, thereby defusing the structure corresponding to the demelting pattern into the layer, wherein the laser beam includes Ultrafast pulsed laser beam with pulse length less than 20 picoseconds.

Therefore, a method of forming a fuse pattern defined by a mask is provided. A plurality of transparent areas in the mask can define the demelting pattern. When compared with the above-mentioned conventional technology, a single laser beam can be used to simultaneously illuminate multiple transparent areas in the mask, and thereby facilitate the melting of the corresponding multiple features in the layer of material. It can be achieved without complicated beam splitting and balanced optical elements, and can be scaled to handle a very large number of features at the same time. Because the laser power can be spread over many different features of the ablative pattern, high laser power can be used. The use of high-power lasers promotes high throughput. The use of ultraviolet radiation allows high spatial resolution to be achieved at reasonable operating costs. Defining the de-melting pattern with a mask (rather than directly via individual beam spots from the laser) allows the de-melting pattern to be defined with high precision, while relaxing the need for the laser beam used to illuminate the mask. The laser can be simply "washed" on the mask with a relatively low resolution.

In an embodiment, the structure corresponding to the fuse pattern includes a regular array of holes. The holes may all have substantially the same size and shape. Therefore, a melting pattern can be used to form a fine metal mesh.

In one embodiment, the imaged portion of the fuse pattern helps to form a plurality of holes in the layer. The plural holes corresponding to each imaging part may include at least 100 holes. Therefore, the laser pulse energy is spread over at least 100 holes, but no complicated beam splitters and balancers are required. In addition, in one embodiment, the sequential imaging of different parts of the fuse pattern can help to form at least 100,000 holes in the layer. Therefore, the light is scanned with a laser beam on the mask, which may greatly increase the number of holes formed. Using a single mask, this approach can scale up to handle more than 500,000 holes, more than 750,000 holes, or even more than 1 million holes.

In an embodiment, each of the holes is a push-pull, so each of the holes has a reduced cross-sectional area in the downstream direction of the laser beam. Then, the guiding step and the scanning step can be repeated for a plurality of mask patterns, and each mask pattern defines the cross-sectional area of the push hole with different depth. This method allows effective and high-precision control of the contour of the push-pull hole. Optimize the push and pull of the holes in the fine metal mesh. During the deposition of the pattern of organic light-emitting diode molecules, the use of the fine metal mesh that minimizes the blur of the pattern edge can improve the performance of the organic light-emitting diode. The efficiency of the manufacturing process. Typically, the push-pull holes of the fine metal mesh are arranged to face (for example, open toward the outside) the substrate on which the organic light emitting diode molecules are deposited. Controlling the angle of pushing and pulling allows to achieve the best balance between the fine metal mesh that provides high resolution and spatial precision (may limit the maximum amount of pushing and pulling), and due to the horizontal wall of the holes in the fine metal mesh Unnecessary interaction (collision) minimizes the redirection of the trajectories of organic light-emitting diodes (in general, it can be improved by increasing the amount of pushing).

As described above, the layer may include a metal layer (for example, to form a fine metal mesh). Depending on the use of the fine metal mesh, the metal layer can have various compositions. For example, the metal layer may be formed from a material having a very low coefficient of thermal expansion, such as indium steel (invar). Other materials can also be used, including non-metallic materials. For example, the layers may include dielectric materials and/or polymers.

In one embodiment, the structure includes a portion of an evaporation mask used to deposit organic light-emitting diode molecules during the manufacture of a display based on organic light-emitting diode molecules. Therefore, a method for depositing organic light-emitting diode molecules can be provided, in which the method for performing laser melting of the present disclosure is used to form an evaporation mask, and the resulting evaporation mask is used to create a pattern defined by the evaporation mask. In the deposition of organic light-emitting molecules.

According to another aspect of the present invention, there is provided an apparatus for performing laser melting. The apparatus includes: an ultraviolet laser, a mask, an optical system, and a scanning arrangement. An ultrafast pulsed laser beam with a pulse length of picoseconds; the mask defines the ablative pattern; the optical system is configured to guide the laser beam through the mask to image a portion of the ablative pattern to the layer of material; and the scanning arrangement is It is configured to scan the mask with a laser beam to sequentially image different parts of the demelting pattern onto the layer, thereby defusing the structure corresponding to the demelting pattern into the layer.

Figure 1 depicts an example device 2 used to perform laser melting. The device 2 uses an ultraviolet laser 6 configured to provide an ultrafast pulsed laser beam 8. Ultrafast pulsed laser beam 8 has less than 20 picoseconds, optionally less than 15 picoseconds, optionally less than 10 picoseconds, optionally less than 8 picoseconds, optionally less than 6 picoseconds, and optionally less than 5 picoseconds. Pulse length in picoseconds. A mask 10 (shown in Figure 2) that defines a fuse pattern 18 is provided. A layer 4 of the material to be processed is provided on the support 12 (for example, a substrate). The support 12 may be provided on a movable table (not shown) for stepping the support 12 to different positions under the laser beam 8. An optical system 13 is provided that guides the laser beam 8 through the mask 10 and onto the layer 4. The optical system 13 images a portion of the demelting pattern 18 onto the layer 4.

The scanning arrangement 14 scans the laser beam 8 to sequentially image different parts of the ablative pattern 18 defined by the mask 10 onto different respective areas of the layer 4 on the mask 10. The structure corresponding to the melting pattern 18 is thus melted into the layer 4. The laser beam 8 will generally scan on the mask 10 without any corresponding movement of the laser 6 or the mask 10 (for example, by suitable scanning optics).

The use of ultraviolet wavelengths allows a high-resolution structure to be formed in the layer 4 without the need for complicated and/or expensive optical components. Typically, resolutions up to 1000 dots per inch can be formed, including, for example, features with critical dimensions of about 3 microns or less, such as dimples or holes.

The device 2 may further include a controller 15 for controlling the overall operation of the device 2. The controller 15 can control the operation of the laser 6 (for example, control when the laser is turned on and off and/or change the parameters of the laser, such as the energy per pulse or pulse repetition rate), the scanning arrangement 14 The operation and the operation of the optical system 13 (for example, controlling the focal height) also control the movement of the support 12 relative to the laser 6 (for example, via a movable stage and an associated motor).

In an embodiment, the device 2 further includes an optical element 16 (for example, including a lens) downstream of the shield 10. The optical element 16 can concentrate the laser radiation 8 from the mask 10 onto the layer 4. In one embodiment, the optical element 16 provides demagnification between the mask 10 and the layer 4. Therefore, the features formed on the layer 4 by melting are smaller than the corresponding features in the mask 10. This approach allows high-resolution patterns to be formed in the layer 4 while distributing the laser energy to a larger area of the mask 10. Therefore, the laser energy density (flux) of the mask 10 is lower than the laser energy density of the mask 10 in other cases. This allows the use of higher laser pulse energy and higher laser power to improve throughput without the risk of damaging the mask 10. In addition, the mask 10 can be manufactured at a lower resolution than the pattern required in the layer 4 to facilitate the manufacture of the mask 10.

In some embodiments, the ablation-produced structure in layer 4 corresponding to the ablation pattern in mask 10 includes a regular array of holes in layer 4. The pitch of the array in layer 4 can be made very small, for example 10 microns or less. All of at least a subset of the holes may have substantially the same size and shape, and/or be otherwise configured to be suitable for use in forming all or part of the fine metal mesh used in the manufacture of organic light emitting diode displays. Way. Figure 2 is a top view of an exemplary mask 10 used to form such a fuse pattern. The mask 10 in this example includes a regular array of transparent areas 20. Each transparent area 20 corresponds to a respective hole formed in the layer 4. Due to the reduction ratio, the spacing of the transparent areas 20 on the mask 10 is generally greater than the spacing of the corresponding holes in the layer 4. For ease of display, the mask 10 of FIG. 2 only includes a relatively small amount of transparent areas 20. In practice, each mask can provide more transparent areas 20 (for example, 100,000 or more, as described below).

In some embodiments, each imaged portion of the fuse pattern 18 in the mask 10 helps to form a plurality of holes in the layer 4. The plurality of holes preferably includes at least 100 holes. For example, each hole in the layer 4 can be formed by directing laser radiation through a corresponding transparent area 20 on the mask 10, and by simultaneously irradiating a plurality of such transparent areas 20 on the mask 10 (E.g., 100 or more) to form the imaged portion of the fuse pattern 18. By simultaneously illuminating many transparent areas 20 in this way, it can help to form many holes in the layer 4 at the same time. This method allows to make full use of the available laser pulse energy and improve output. When combined with the scanning step, a very large number of holes can be formed quickly. For example, the sequential imaging of different parts of the fuse pattern can be through 1000 or more sections of the fuse pattern, each of which helps to form at least 100 holes and helps to form at least 100,000 holes in the layer .

In the example schematically shown in FIG. 2, the demelting pattern 18 defined by the mask 10 includes an array of square transparent areas 20. In other embodiments, the transparent area 20 may have other shapes, and thereby form features or holes of different shapes in the layer 4. For example, the transparent area 20 may be rectangular, circular, or elliptical.

Fig. 3 depicts an example scanning path 22 of the laser beam spot 9 on the mask 10 (as viewed from the laser 6) during the scanning step. The laser beam spot 9 is the part of the mask 10 that is illuminated by the laser beam 8 at any given time, and defines the corresponding part (imaging part) of the ablative pattern imaged on the layer 4 at this time. The scan path 22 can be described as a raster scan. Other scan paths can be used. The scan path 22 can be adapted to avoid areas in the layer 4 that do not require structure. The scanning path 22 may additionally or alternatively consider other factors, such as the characteristics of the laser 6 used (for example, the power of the mask 10 and/or the size of the light spot 9), the fuse pattern 18 in the mask 10, and / Or the nature of layer 4.

FIG. 4 is a top view of the layer 4 after the structure 24 corresponding to the melting pattern 18 (for example, a square array of holes) defined by the mask 10 is melted into the layer 4. The structure 24 can be formed by a single scan on the mask 10 or by multiple scans on the mask. For example, in the first scan on the mask 10, at least a subset of the features of the structure may be melted through layer 4 to only a portion of the depth specified by the structure, thereby providing partially formed features. Repeating the scanning process allows each partially formed feature to be irradiated multiple times until each partially formed feature becomes fully formed (for example, the hole extends all the way through layer 4). This practice can conveniently allow heat to dissipate between successive melting processes, thereby helping to prevent unnecessary damage to areas other than the target area for melting. In one embodiment, the laser beam spot 9 scans several times along the scanning path 22 discussed above with reference to FIG. 3. During the manufacturing process, multiple scans can be performed without providing any relative movement between mask 10 and layer 4.

As depicted in Figure 4, the structure 24 corresponding to the fuse pattern 18 is provided by a mask 10 and can only cover a small part of the layer 4 to be processed. Therefore, the method can be repeated to handle other required parts of layer 4. In one embodiment, a stepping and scanning process is used to form the structure 24, and the layer 4 is disposed at a first position relative to the mask 10. Then provide relative movement between the layer 4 and the mask 10 (usually by moving the layer 4 and fixing the mask 10 and the optical element 16 in position) to bring the layer 4 to the position relative to the mask 10. Two positions, and the scanning process is repeated to form other examples of the structure 24 adjacent to the previously formed example. The copy process can then be repeated to process the entire layer 4. Therefore, the above-mentioned guiding step and scanning step can be repeated for a plurality of different parts of the layer 4 with respect to the mask 10 to melt the structure corresponding to the melting pattern to a plurality of different locations on the layer 4, and thereby The structure built in layer 4 is larger than the structure built without stepping into layer 4.

In one embodiment, as depicted in FIGS. 5 to 7, each of the holes 25 of the structure 24 formed by dissolution is a push-out, and has a cross section that decreases in the downstream direction of the laser beam 8 area. In one embodiment, the laser beam 8 is repeatedly guided through the mask 10 and onto the layer 4, and the laser beam 8 is used to scan a plurality of different mask patterns on the mask 10 to control the push. Each mask pattern defines the cross-sectional area of the push hole 25 at different depths. For example, the first mask pattern may be provided with a first plurality of transparent regions 20 corresponding to the respective plurality of holes 25 formed in the layer 4, and the second mask pattern may be provided with a plurality of respective respective ones corresponding to the same The second plurality of transparent areas 20 of the hole 25, and the third mask pattern may be provided with a third plurality of transparent areas 20 corresponding to the same respective plurality of holes 25, the transparent area 20 of the first mask pattern is larger than The transparent area 20 of the second mask pattern is larger than the transparent area 20 of the third mask pattern. FIG. 5 schematically shows an exemplary result of the process using the first mask pattern, forming a shallow dimple having a diameter of 26. As shown in FIG. Fig. 6 schematically shows an exemplary result of the process using the second mask pattern, the dent has been deepened and has a narrower diameter 28. FIG. 7 schematically shows an exemplary result of the process using the third mask pattern. The melt has penetrated through the layer 4 and a push hole 25 with a diameter of 30 is formed at the deepest point of the dent 25. The change in the size of the transparent area in the first mask pattern, the second mask pattern, and the third mask pattern affects the diameter 26, 28, and 30 at different points along the push, thus allowing high-precision control of the push Outline.

The method of repeating the guiding step and the scanning step for a plurality of mask patterns that define different respective melting patterns is not limited to the case where the structure formed is a regular array of holes, and it is not limited to different melting patterns corresponding to different holes. The depth of the situation. Practice can be applied to different or more complex structures. This method is useful as long as it is beneficial to control the shape of the dent or hole in the layer 4 according to the depth of the dent or hole. In order to achieve depth-based shape control, it is generally desirable to repeat the guiding step and the scanning step, resulting in different laser melting patterns being applied to the same or overlapping regions of the layer 4. Usually this will involve repeated guidance and scanning without any change in the relative position between the mask 10 and the layer 4, for example the same part of the layer 4 is processed each time. As outlined in Figure 8, multiple mask patterns can be provided on separate masks 101, 102, and 103, or as outlined in Figure 9, different areas 10A, 10B, and 10C are in the same mask. 10 on.

Other methods of controlling push can be used in combination with the above methods or as an alternative. For example, in one type of embodiment, by controlling the flux of the laser beam 8 to the mask 10 (pulse energy density: the energy of the laser pulse divided by the area irradiated by the laser pulse), at least part of the To control the push and pull. For example, the laser beam 8 can be scanned on the mask 10 several times, and at least two scans are performed with different fluxes. The flux of the laser beam 8 incident on the layer 4 affects the push-pull angle of the wall of the melted pocket in the layer. A higher flux results in a smaller (more upright) push angle. A smaller flux results in a higher (less upright) push-pull angle. The ability to vary the flux according to the depth in the layer 4 is provided to provide a useful additional degree of freedom for adjusting the internal shape (for example, a push-out profile) of the structure formed in the layer 4.

Based on the foregoing, in one category of embodiments, during the formation of the hole, for each of the one or more holes, the flux of the laser beam 8 to the mask 10 is changed. The changing flux in the mask 10 results in a corresponding change in the flux in layer 4. The change is such that during the formation of portions of holes of different depths in layer 4, the flux at the mask (and therefore in layer 4) is different, thereby controlling the change of the pull-out angle of the holes according to the depth in layer 4.

In an exemplary process, a laser beam 8 provides a first flux to the mask 10 to perform the first scan on the mask 10. For example, the scan can follow the above description and refer to the scan path 22 of FIG. 3. The flux of the laser beam 8 can be such that after this first scan on the mask 10, a structure is formed in the layer 4 that only partially extends through the layer 4 (similar to the situation in Figure 5). Then, a laser beam 8 provides a second flux lower than the first flux, and a second scan is performed on the mask 10. The result of this scan is to deepen the structure formed in the first scan. However, during the second scan, due to the lower flux of the laser beam 8, the push-pull angle also increases. Then, a laser beam 8 provides a third flux lower than the second flux, and a third scan is performed on the mask 10. The result of this scan is to deepen the structure formed in the second scan until the melt breakthrough passes to the other side of layer 4. During the third scan, the low flux of the laser beam 8 indicates a further increase in the push angle at the newly arrived depth. Figure 10 shows the outline of the hole created by this method. Therefore, this approach provides an additional or additional way to control the shape of the push-pull in the hole. Although reference has been made to this embodiment exemplified by three scans, any number of scans can be used. In addition, it is unnecessary to adjust the flux in the above-mentioned manner, but on the contrary, the flux can be changed in any suitable manner. If the flux in successive scans is gradually increased, a hole profile of the type shown in Figure 11 will be created. In addition, the flux of the laser beam 8 in each scan does not have to be different, as long as there is a difference in at least two scans. The throughput can be increased or decreased between different scans.

2: equipment 4th floor 6: Ultraviolet laser 8: Ultrafast pulsed laser beam/laser beam/laser radiation 9: Laser beam spot 10,101,102,103: Mask 10A, 10B, 10C: area 12: Support 13: Optical system 14: Scan layout 15: Controller 16: optical components 18: Melting pattern 20: Transparent area 22: Scan path 24: structure 25: hole 26, 28, 30: diameter

The embodiments of the present invention will now be described, by way of example only and with reference to the drawings, in which: Figure 1 is a schematic side view of the equipment used to perform laser melting; Figure 2 is a top view of a mask that can be applied to the device shown in Figure 1; Figure 3 is the top view of the mask, showing how the laser beam can be scanned on the mask; Fig. 4 is a top view of the layer shown in Fig. 1 with a fuse pattern being melted in the layer; Figures 5 to 7 are side cross-sectional views showing different stages of the melting of the push-pull hole; Figure 8 depicts multiple mask patterns for different scans on the same area of the layer, where the mask patterns are provided on separate masks; Figure 9 depicts multiple mask patterns for different scans on the same area of the layer, providing mask patterns on different areas of the same mask; and Figures 10 and 11 show side cross-sectional views of different hole pushing profiles formed by reducing or increasing the laser energy density (flux).

2: equipment

4th floor

6: Ultraviolet laser

8: Ultrafast pulsed laser beam

10: Mask

12: Support

13: Optical system

14: Scanning device

15: Controller

16: optical components

Claims (19)

A method for performing laser melting, the method includes: Guiding an ultraviolet laser beam through a mask to image a part of a fuse pattern defined by the mask onto a layer of material; and Scan the laser beam to sequentially image a plurality of different parts of the demelting pattern onto a plurality of different areas of the layer on the mask, so as to map a structure corresponding to the demelting pattern Melt into this layer, The laser beam includes an ultrafast pulsed laser beam with a pulse length less than 20 picoseconds. The method of claim 1, wherein the structure corresponding to the fuse pattern includes a regular array of holes. As in the method of claim 2, wherein all of the at least a subset of the holes have substantially the same size and shape. Such as the method of claim 2 or claim 3, wherein each of the holes is a push, so that each of the holes has a cross-sectional area that decreases in a downstream direction of the laser beam. The method of claim 4, wherein for each of one or more of the holes, a flux of the laser beam in the mask changes during the formation of the hole, and in the plurality of parts of the hole During the formation of, the change makes the flux at multiple different depths in the layer of material different, so that a change in a push-pull angle of the hole is controlled according to the depth in the layer of material. Such as the method of claim 4 or claim 5, wherein the guiding step and the scanning step are repeated for a plurality of mask patterns, and each mask pattern defines a cross section of the push-pull holes at a different depth area. The method according to any one of claim 2 to claim 6, wherein each imaged part of the fuse pattern helps to form a plurality of holes in the layer. The method of claim 7, wherein the plurality of holes corresponding to each imaging part includes at least 100 holes. The method of claim 8, wherein the sequential imaging of a plurality of different parts of the ablative pattern helps to form at least 100,000 holes in the layer. Such as the method of any one of claim 2 to claim 9, wherein a pitch of the array is less than 10 micrometers. The method according to any one of the foregoing claims, wherein the guiding step and the scanning step are repeated to define a plurality of mask patterns of a plurality of different melting patterns. Such as the method of claim 11, wherein the guiding step and the scanning step are repeated, and the different laser melting patterns are applied to the same or overlapping regions of the layer. Such as the method of claim 11 or 12, wherein the plurality of mask patterns are provided on a plurality of separate masks. Such as the method of claim 11 or 12, wherein the plurality of mask patterns are provided on a plurality of different areas of the same mask. A method as in any one of the preceding claims, wherein the layer includes a metal layer. The method of any one of the preceding claims, wherein the guiding step and the scanning step are repeated for a plurality of different parts of the layer with respect to the mask, so as to melt the structure corresponding to the melt pattern To many different locations on the floor. A method according to any one of the preceding claims, wherein the structure includes a part of an evaporation mask for depositing a plurality of organic light-emitting molecules during the manufacture of a display based on organic light-emitting molecules. A method of depositing organic light-emitting molecules, including: By executing the method of claim 16 to form an evaporation mask; and The vapor deposition mask is used to deposit a plurality of organic light-emitting molecules in a pattern defined by the vapor deposition mask. A device for performing laser melting, the device includes: An ultraviolet laser configured to produce an ultrafast pulsed laser beam with a pulse length of less than 20 picoseconds; A mask, defining a melting pattern; An optical system configured to guide the laser beam through the mask to image a part of the ablative pattern onto a layer of material; and A scanning arrangement configured to scan the mask with the laser beam to sequentially image different parts of the demelting pattern onto the layer, thereby destructing a structure corresponding to the demelting pattern Melt into this layer.

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