TWI556284B - Systems and methods for non-periodic pulse sequential lateral solidification - Google Patents

Description

System and method for non-periodic pulse continuous lateral crystallization [ Reciprocal related applications ]

The present application claims priority to U.S. Patent Application Serial No. 61/294,288, filed on Jan. The full text is attached for reference.

All patents, patent applications, patent publications and publications mentioned herein are expressly incorporated by reference. In the case where the application of the application is inconsistent with the presentation of the document, the application shall be examined and examined.

The present invention relates to systems and methods for non-periodic pulsed continuous lateral crystallization.

In the field of semiconductor processing, some teachings have described the conversion of amorphous germanium films into polycrystalline films. One of the teachings is continuous transverse crystallization (SLS). SLS is a pulsed laser crystallization process, which can produce a polycrystalline film with elongated grains on a substrate, such as a heat-resistant substrate (such as glass and plastic), but not limited thereto. The SLS system and process examples are described in commonly-owned U.S. Patent Nos. 6,322,625, 6, 368, 945, 6, 555, 449, and 6, 573, 531, the entireties of each of which are incorporated herein by reference.

The SLS uses position controlled laser pulses to melt the amorphous or polycrystalline film regions on the substrate. The molten region of the film is then laterally crystallized into a directional crystallite structure or a plurality of positionally controlled large single crystal regions. Typically, the melting/crystallization process is repeated continuously throughout the surface of the film. One or more devices, such as image sensors, active matrix liquid crystal displays (AMLCDs), and active matrix organic light emitting diode (AMOLED) display devices, can then be fabricated from the crystalline film. In AMLCD and AMOLED display devices, a thin film transistor (TFT) regular array or TFT circuit is fabricated on a transparent substrate, and each transistor or circuit is used as a pixel controller.

In conventional SLS systems, the factor of successful crystallization is the accuracy of the platform, which moves the sample relative to the laser pulse. For the current four-generation two-dimensional (2D) projection SLS system, the platform moves at tens of centimeters per second (cm/s), such as 18 cm/s. Such platforms will partially deviate from the perfect moving line. Deviation is collectively referred to herein as platform shaking. Here, "platform shaking" means that when the platform moves along the laser path, its position will change and deviate from the predetermined position. The variation is, for example, that when the platform moves in the x direction, the platform moves slightly in the direction of the direction y. The 2D projection system produces a two-dimensional patterned beam for SLS. Other methods can produce beam lines for performing SLS.

The problem associated with conventional single-scan and platform-sliding in the secondary illumination SLS is that the long grain boundaries of the material produced by two consecutive laser pulses (ie, the secondary illumination material) are non-equidistantly spaced. The single-scan SLS process refers to the SLS process of completely crystallizing the area on the substrate in a single scan. The secondary illumination SLS refers to the SLS process of completely crystallizing a specific partial region with two laser pulses. The platform shake between the two pulses will cause the second pulse to overlap asymmetrically with the first pulse. Ideally, the second pulse beam is located in the middle of the region illuminated by the first pulse beam such that there is a fixed interval between the grain boundaries produced by the secondary illumination process. If the second pulse beam is not properly positioned due to platform shaking, the grain of one crystal column may be shorter than the grain of the adjacent crystal column, and many grains remain in the wide crystal column of the width of the incompletely extended crystal column. (such as occluding crystal grains). In addition, beam distortion caused by various aberrations of the projection light will also cause partial asymmetric overlap of the second pulse during scanning. Here, "beam distortion" refers to projection light aberration, which results in uneven beamforming.

Non-periodic pulse SLS methods and tools for continuously triggering lasers using position control are described herein. The system may employ multiple lasers or a single laser to produce different non-periodic laser pulses in the crystallization process, i.e., where each laser pulse causes a respective melting and crystallization cycle. One or more lasers are used to coordinate the pulse sequence and illuminate and crystallize the selected film regions in a single scan. For example, a fast laser pulse sequence from two different laser sources can increase the effective pulse rate for processing local regions compared to a single source pulse rate. It also allows for greater overlap between successive pulses without reducing the speed of platform movement. The overlap area of the film between the pulses of the two lasers can be greater than 70% or 95%, and in some cases greater than 99%. Such a large degree of overlap can alleviate the problem of platform shake and laser beam distortion.

In any embodiment, the system and method for non-periodic pulsed continuous lateral crystallization is directed to treating a film. A method of processing a film while advancing the film in a selected direction includes illuminating the first region of the film with the first laser pulse and the second laser pulse, and illuminating the second region of the film with the third laser pulse and the fourth laser pulse The time interval between the first laser pulse and the second laser pulse is less than half of the time interval between the first laser pulse and the third laser pulse. In some embodiments, each pulse provides a shaped beam of light and has a fluence sufficient to melt the thickness of the film to form a molten region that crystallizes laterally upon cooling. In some embodiments, the first and second regions are adjacent to each other. In some embodiments, the first and second regions are separated by a distance.

In any embodiment, the first laser source generates a first laser pulse and a third laser pulse, and the second laser source generates a second laser pulse and a fourth laser pulse. In some embodiments, the first and second laser sources generate pulses at a fixed rate. In some embodiments, the first and second lasers are the same. In some embodiments, the first and second lasers are different. In some embodiments, the film continues to advance in a selected direction.

In any embodiment, the first and second laser pulses each provide a beam of light that overlaps the first region of the film, and the third and fourth laser pulses each provide a beam of light that overlaps the second region of the film. The amount of overlap of each region is greater than 90%, such as greater than 95% or greater than 99%.

In any embodiment, the shaped beam can be obtained by directing a laser pulse through the mask and/or including a plurality of beams. In some embodiments, the beam is positioned at an angle relative to the edge of the film. In some embodiments, the edge of the film is positioned at an angle relative to the scan direction. In some embodiments, the shaped beam is a dot pattern.

In any embodiment, the first and second regions are spaced apart from each other and are separated by an unirradiated film region. In some embodiments, the first and second regions overlap, for example, by 10% or 1%.

In any embodiment, the electronic device is fabricated in the first region and the second region, and the region is sized to accommodate circuitry belonging to a node of the matrix type electronic device.

In one aspect, this document relates to films treated in accordance with the methods described. The film can be used to fabricate electronic devices, including devices having thin film transistors in the first and second regions of the film.

In one aspect, the present invention relates to a method of treating a film while advancing the film at a fixed velocity in a selected direction, comprising illuminating the first region of the film with a first beam provided by a laser pulse from a primary laser source. A second beam of light provided by the laser source of the laser source illuminates a second region of the film, and a third beam provided by a laser pulse from the primary laser source illuminates a third region of the film. In some embodiments, the first, second, and third beams are fluent enough to melt the entire film thickness of the irradiated film region and laterally crystallize into one or more laterally grown crystals upon cooling, and first and second The amount of illumination overlap between the regions is greater than the amount of illumination overlap between the second and third regions.

In one aspect, this document is directed to a method of treating a film while advancing the film in a selected direction. The method includes, at a first time, generating a first shaped beam from a laser pulse of a primary laser source, and illuminating a first region of the film with a first shaped beam to form a first molten region that laterally crystallizes upon cooling Forming a first set of crystalline regions; at a second time, generating a second shaped beam from a laser pulse of the secondary laser source, and illuminating the first region of the film with the second shaped beam to form a second molten region, It crystallizes laterally into a second set of crystalline regions upon cooling; and at a third time, a third shaped beam is generated from another laser pulse of the primary laser source, and a second region of the film is illuminated with a third shaped beam A third molten region is formed which is laterally crystallized into a third set of crystalline regions upon cooling. In some embodiments, the time interval between the first time and the third time exceeds twice the time interval between the first time and the second time.

In one aspect, this document relates to a system for processing a film, including primary and secondary laser sources for generating laser pulses, a system for generating a shaped beam from a laser pulse, for securing a film onto a substrate. The working surface, the platform for moving the film relative to the beam pulse, and thereby generating the direction of the laser beam pulse propagation on the surface of the film, and the computer for processing the platform to synchronize the laser pulse command, so that the film loaded on the mobile platform is A region is illuminated by a first set of one or more shaped beams provided by a laser pulse from a primary source, the second region of the film being provided by a second set of one or more shaped laser pulses from a secondary source The beam is illuminated, and the third region of the film is illuminated by a third set of one or more shaped beams provided by laser pulses from the primary source. In some embodiments, the processing instructions are for moving the film relative to the beam pulse in a direction of propagation to illuminate the first and second regions, wherein the amount of illumination overlap between the first and second regions is greater than the illumination between the second and third regions The amount of overlap. In some embodiments, the system also includes a system for sample alignment.

Non-periodic pulse SLS methods and tools that continuously trigger multiple lasers using position control are described herein. Multiple lasers can produce different non-periodic laser pulses in the crystallization process, i.e., the difference is that each laser pulse causes a respective melting and crystallization cycle. Two or more lasers are used to coordinate the pulse sequence and illuminate and crystallize the selected membrane regions with a single scan. The fast laser pulse sequence from two different laser sources can increase the effective pulse rate for processing local regions compared to a single source pulse rate. It also allows for greater overlap between successive pulses without reducing the speed of platform movement. The overlap area of the film between the pulses of the two lasers can be greater than 70% or 95%, and in some cases greater than 99%. Such a large degree of overlap can alleviate the problem of platform shake and laser beam distortion.

In addition, non-periodic pulsed SLS methods and tools can also be used to perform selective area crystallization (SAC) films whereby only the film regions of the electronic device to be formed are crystallized. The non-periodic pulse SLS method and tool provide SAC in such a way that the first pulse of two or more lasers partially overlaps, and in some cases substantially overlap (ie, greater than 70%), causing the first region of the film to grow slenderly, Then, the repetition rate of the laser is interrupted for a period of time, and then the second pulse of the two or more lasers is substantially overlapped, so that the second region of the film undergoes slender crystal growth. The laser pulse timing resulting in a substantial overlap of the non-periodic laser pulse sequence and the illuminated area is illustrated in Figures 5A-5C, which will be described in detail later. This method and system can be applied to a conventional two-dimensional projection SLS process with high throughput.

Low-temperature polycrystalline germanium (LTPS) technology is required for large-diameter AMOLED displays that produce sufficient brightness and/or lifetime. SLS is one of the most popular laser-based LTPS technologies. The SLS system is expected to have a large platform to handle large panels and more laser power to achieve sufficient output (high pulse repetition rate and / or high pulse energy). Although having a fast platform and high pulse repetition rate alone has been shown to reduce wobble and its impact on microstructures (platform inertness and short pulse interval), the need for large platforms and small grains still makes platform design more challenging and The platform is also more expensive. On the other hand, the non-periodic pulse can greatly shorten the time of two consecutive overlapping pulses to a moment when the platform deviation from the two pulses is substantially unchanged, and at the same time effectively reduce the difficulty of the platform design.

Increasing the amount of overlap between pulses is beneficial to reduce the negative effects of platform shake and proper overlapping image distortion between beams. The implementation of the non-periodic pulse SLS may employ a beam that is oriented to move relative to the platform in any direction. However, in practice, vertically oriented beams (such as the vertical platform moving direction) can provide a larger amount of pulse overlap, so the method is more beneficial. For SLS using long rectangular beams, such as a secondary illumination SLS process, the maximum vertical overlap can be established using the primary vertical directional beam. Although a horizontal beam can be used in accordance with the non-periodic pulse SLS method, it is preferable to use a vertical beam in order to achieve a high degree of overlap between pulses. "Vertical Beam Alignment" is described in U.S. Patent Application Serial No. "Systems and Methods for Uniform Sequential Lateral Solidification of Thin Films Using High Frequency Lasers" 12/063,814, the entire contents of which are hereby incorporated by reference.

To clearly explain the features and advantages of the non-periodic pulse SLS, a single scan and a secondary illumination SLS are first described. Figure 1 shows an example of a system that can be used in a 2D SLS process. A light source, such as excimer laser 110, produces a pulsed laser beam that passes through pulse delay 120 before passing through optical components such as mirrors 130, 140, 160, telescope 135, homogenizer 145, beam splitter 155, and lens 165. And the attenuation plate 125. The laser beam pulse then passes through a mask 170 that is placed on a moving platform (not shown) and projection light 195. The projection light reduces the size of the laser beam while increasing the intensity of the light energy at a predetermined position of the illumination film 199. Membrane 199 is placed on a precision x-y-z platform 198 that accurately places film 199 under the beam and assists in focusing or defocusing the image of the mask 170 produced by the laser beam at a predetermined location on film 199. In some embodiments, the platform includes a mechanism that moves the work surface on which the substrate is placed and/or a projection lens to move the substrate and the projection lens relative to each other.

The characteristics of the laser crystallization system that can be used in the SLS process depend primarily on the laser source. For example, high frequency lasers with low energy pulses (several kilohertz or up to tens of kilohertz or more) are used to create elongated lines for so-called "line scan SLS". The beam length is typically larger than one or more display sizes and is a fraction or equal to the glass panel size of the cut display. The fraction can be from about 1/2 to about 1/16 of the panel, such as 1/4 of the panel. Low-power lasers with high power (such as 300 Hz or 600 Hz or more and 300 watts (W) or 600 W or more) are not suitable for line-scan SLS mode because the pulse energy is too high (1 Joule (J) rating) So that a rectangular beam is formed to scan the entire film surface. A special SLS system type using this laser (such as Japan Steel Works, Ltd. from Japan) uses a two-dimensional (2D) projection system to produce typical short-axis dimensions of about 0.5 mm (mm) to 2.0 mm and typical long-axis dimensions. A rectangular laser pulse of about 15 mm to 30 mm. At least one dimension of the molten region for continuous lateral crystallization is 1 to 2 times the lateral grain growth, for example, about 2 micrometers (μm) to 6 μm. Therefore, a rectangular laser beam can be shielded to provide a plurality of small-sized beams. Instead of using a mask with other optical means of controlling the beam, for example, creating an interference pattern that forms a mask-like light pattern, a plurality of appropriately sized beams can also be provided.

In an SLS mode using a plurality of beams to form a highly uniform crystalline film, illuminating a particular region of the film with two different laser pulses to completely crystallize the film provides a faster way to fabricate the polycrystalline semiconductor film. This method generally refers to secondary illumination of the SLS. Additional details of secondary illumination and other SLS methods and systems can be found in U.S. Patent No. 6,368,945, entitled "Method and System for Providing a Continuous Motion Sequential Lateral Solidification." The full text is attached for reference. The secondary illumination SLS can be performed in a single scan. This is called a single scan SLS, in which the beam pulse is patterned into a beam array, and its long axis is usually aligned with the parallel scan direction. This can be seen as "continuous movement of providing a single scan and U.S. Patent No. 6,908,835, the entire disclosure of which is incorporated herein by reference.

Figure 2A illustrates a mask as described in U.S. Patent No. 6,908,835, which is incorporated herein by reference to the SLS method of the Figure 1 system for a single scan of the continuous moving SLS process. The mask includes a plurality of rectangular arrays of rectangular slits 210, 215 that transmit and shape the laser beam to produce a plurality of beam illumination films. The other part of the mask (non-slit) is opaque. The mask can be fabricated from a transparent substrate such as quartz and includes a metal or dielectric coating that is etched into a mask of any shape or size in a conventional manner. It should be understood that the illustrated mask is merely illustrative, and that the size and aspect ratio of the slit are substantially variable and are related to the predetermined processing speed, the energy density required to melt the film of the illuminated area, and the available pulse energy. A set of slits 210 are offset from the second set of slits 215 toward the x-axis and the y-axis. Generally, the aspect ratio of a particular slit width to length may vary, such as 1:5 to 1:200 or more. The length 265 of the mask feature selects the size of the device to be fabricated on the surface of the substrate. The width 260 and spacing 240 of the mask features may also vary. In some embodiments, the width 260 is chosen to be small enough to avoid nucleation of small grains in the molten region, but large enough to maximize lateral crystal growth of each laser pulse. For example, the mask features have a length 265 of about 25 to 1000 μm and a width 260 of about 2 to 5 μm, which can be multiplied by any reduction factor present in the subsequent projection light, for example, by a factor of 4 to 6.

In operation, the platform continues to move the film in the -x direction such that the long axis of the slit of the 2A mask is substantially parallel to the scanning direction. As the film moves, the laser produces pulses at a specific frequency (eg, 300 Hz) that is masked and shaped. The film velocity (such as the plateau velocity) is chosen such that as it moves, the beams within subsequent laser pulses overlap.

2B-2D illustrates a secondary illumination SLS process using a mask of FIG. 2A to focus on a film region, which displays a second set of dual array slits 210 (right) and a second when scanning the film in the -x direction The amount of illumination overlap between a set of dual array slits 215 (left). In this example, the width 260 of the mask slit 210 is about 5 [mu]m and the spacing 240 is about 2 [mu]m. During the first pulse, the membrane area is illuminated with a first laser pulse. As shown in FIG. 2B, this region is illuminated by a first set of beams from the second array 210 of masks, and the laser pulses fuse the regions 211, 212, 213 on the sample, wherein the width of the melt region 214 is about 5 μm. The spacing 217 is about 2 μm, which can be multiplied by any scalar factor existing in the subsequent projection light, for example, by 4 to 6 times. As shown in FIG. 2C, the first laser-induced irradiation regions 211, 212, and 213 are crystallized from the melting boundary 216 to the melting region, and thus the polysilicon 221 is formed in the irradiation region.

The film continues to move in the x direction, and the second illumination caused by the second set of beam illumination areas of the first array 215 of masks melts the remaining amorphous regions 223, 225, 227, 229 (Fig. 2C). It extends to the new crystalline region 221 and the initial seed region 224 to be melted. As shown in Fig. 2D, when the molten region is crystallized, the crystal structure constituting the central portion 228 grows outward, thereby forming a uniform long-grain polycrystalline germanium region. In addition, FIG. 2D shows four crystal columns 231, 232, 233, and 234 which are separated from each other by the elongated grain boundaries 235, 236, 237, and 238. The long grain boundaries 235, 236, 237, 238 correspond to the centers of the respective melting regions. There are a plurality of substantially parallel laterally growing crystals 239, 241, 242, 243, 244 in the crystal column.

Figure 3 illustrates an exemplary film illumination that has been illuminated with two subsequent laser pulses. As described above, during cooling, the beam illuminates and melts the individual illumination regions 380 of a particular column, and the crystallization of this region will grow from the edge of the region to the middle of the region. Therefore, in the central region 350 of the illumination area, the beam edges are aligned in the x direction (parallel scanning), and the grains extend substantially in the y direction (vertical scanning). The film includes a first set of crystalline regions 345 that have been masked by the 2A pattern to form a first pulse of the first set of beams (corresponding to the slit 215) as the film moves in the -x direction and is scanned in the +x direction The second pulse illumination of the second set of beams 340 (also corresponding to slit 215) is formed by masking in FIG. 2A. When scanning the sample, the end portion of the second set of crystalline regions 340 produced by the second laser pulse 340 partially overlaps the front end portion of the first set of crystalline regions 345 produced by the first laser pulse 345. The crystalline portion of the third set of crystalline regions 340' also produced by the second laser pulse overlaps the sides of the first set of crystalline regions 345 to fill the spaces between the regions of the first set of crystalline regions 345. When the film is scanned in the x direction, the entire surface of the film will crystallize.

Since the beam is very long, many crystalline regions have grains oriented in the y direction. In contrast, in the front end and end regions 360, 370, part of the crystal grows from the end of the region and substantially extends in the x direction (parallel scanning), and the others grow in the oblique scanning direction. These areas are known as "edge areas." Here, the edge of the beam regenerated by the melting portion causes the grain to grow laterally and obliquely from the edge, which may form a processed product because it deviates from the predetermined lateral growth direction.

According to the above method of continuous lateral crystallization, the entire region can be crystallized using only two laser pulses. This method is hereinafter referred to as a "secondary irradiation" process, which implies that only two laser pulses (irradiation) are required to complete the crystallization. Further details of the secondary irradiation process can be found in the method entitled "Methods for Producing Uniform Large-Grained and Grain Boundary Location Manipulated Polycrystalline Thin Film by Continuous Lateral Crystallization to Produce Uniform Large Grains and Grain Boundary Positions". "U.S. Patent No. 6,555,449, the disclosure of which is incorporated herein by reference.

The aforementioned secondary illumination SLS process can be used to crystallize the tantalum film used to fabricate small diameter active array displays (e.g., for mobile applications), for example, fabricated from a glass panel of about 730 mm x 920 mm. Manufacturing large diameter active array displays (such as monitors or TV applications) requires processing large panels, for example up to 2200 mm x 2500 mm, or even larger. The obstacle to the development of large panel manufacturing tools is the linear platform for moving panels: it is not easy to operate such a large platform with the accuracy required by conventional secondary illumination SLS processes. The following describes some of the problems encountered with the above-mentioned SLS using an inaccurate platform, especially the impact of platform shaking.

4A-4E illustrate the limitations and problems associated with the aforementioned secondary illumination SLS process. Figure 4A depicts a typical mask pattern for a secondary illumination SLS process to produce a beam. The mask 400 for the secondary illumination SLS process includes a double row of slit arrays 402, 404 that are offset from one another and correspond to the 3A mask. Although the slits 402, 404 are shown to have a triangular bevel, the slits may have other shapes. For example, the slit has a trapezoidal bevel and/or a rounded edge. As shown in Figures 2A and 3A, rectangular slits can also be used. Further details of the selection of beam and gap widths and other examples of slit shapes or edge shapes can be found in WO 2005/029546 and U.S. Patent No. 6,908,835, the entire disclosure of each of which is incorporated herein by reference.

FIG. 4B illustrates a secondary illumination SLS process film 410 on which a plurality of pixels 415 comprising a thin film transistor (TFT) or circuit 420 and electrode 430 are formed. As previously mentioned, this is a single scan SLS process in which each laser pulse is patterned into a beam array with its long axis aligned with the parallel scan direction. The beam pulse forms a plurality of crystalline regions, including a first crystalline region 440 and a second crystalline region 450. The illustrated crystalline regions 440, 450 have a length of about 25 mm and a width of about 1.2 mm. The pixel spacing (pixel center-to-center spacing) depends on the diameter of the matrix and the number of nodes in the matrix (where the matrix corresponds to the back of the active matrix of the LCD or OLED display, the nodes correspond to the individual pixels on the back of the active matrix), and the size It can be used for 600 μm or more of a large array such as a large TV. The second crystalline region 450 is shown to overlap the first region 440 by about 50%. Line 460 represents the scan direction (which is the pulse scan direction) and non-linearity represents the effect of platform wobble (y-direction) during scanning, which will result in poor pulse overlap.

FIG. 4C illustrates a second illumination SLS scan using the foregoing method and the mask pattern of FIG. 4A. The first laser illumination illuminates and melts a portion of the film in a pattern corresponding to region 440, which is shown as region 4C (dashed line) (ie, the first melt region). The second illumination illuminates and melts a portion of the film in the pattern of the corresponding region 450, which is represented as a 4C-th image region 470 (solid line) (ie, a second melt region). Each molten zone cools and forms crystalline regions 460, 470. As shown in Fig. 4C, the crystal regions 460, 470 include a plurality of regions 461, 471, etc., which respectively correspond to the beam generated by the mask, and have unexposed regions between the plurality of regions 461, 471. Each molten region is cooled and crystallized into a region 461 before the next laser beam illuminates the surface of the film and forms a molten region of the crystalline region 471. FIG. 4C also shows an overlapping portion 480 of the first crystalline region 460 and the second crystalline region 470. For example, the overlapping portion 480 includes overlapping portions of the regions 461a and 471a. Thus region 480 can be fully crystallized by overlap and different illumination, which corresponds to the right side of region 461 and the left side of region 471, and as described in Figures 2-3, corresponds to the extended portion of the lateral grain of region 480.

The shaking of the platform causes a laser pulse misalignment between subsequent laser pulses, as indicated by the misalignment of region 4C of Figure 4C. Due to the shaking of the platform, the first crystal column from the illumination region 461 of the first laser pulse is not precisely aligned with the first crystal column from the illumination region 471 of the second laser pulse. Misalignment results in an asymmetric overlap of the illuminated areas during the second laser pulse. Therefore, the first crystal column from the irradiation region 471 of the second pulse is shifted in the direction of the arrow 465 by a distance from the first crystal column of the irradiation region 461 of the first laser pulse (Fig. 4D).

Laser pulse misalignment results in a long grain boundary with uneven spacing in the final product. The long grain boundary is the midline formed by the convergence of the two lateral growth crystal front ends. Fig. 4E is a schematic view showing the position of the long crystal boundary of the region 480 after the secondary irradiation of the SLS. It depicts the midline of the long grain boundaries 490', 491', 492', 493' corresponding to the final product. As shown in Fig. 4E, the center line is unevenly spaced. Figure 4E further illustrates four crystalline regions 490, 491, 492, 493 separated by elongated boundaries 490', 491', 492', 493' and including laterally extending grains 490A, 490B located in region 490. , 490C, etc. The midline or long crystal boundaries 490', 491', 492', 493' form an electron flow barrier and reduce the electron mobility in the resulting TFT. The decrease in electron mobility is more related to the precise position of the long crystal boundaries in the channel region of the TFT and its source and drain regions. The long grain boundaries are preferably evenly spaced to provide a more uniform material.

As shown in Fig. 4E, the crystalline regions are unevenly spaced; the regions 491 are wider than the regions 490. The unevenness of the center line is equivalent to the unevenness of the crystal column caused by the platform shake during the secondary irradiation process, which not only affects the uniformity of the material, but also limits the feasible beam width and the lower limit of the pitch. That is, unevenness results in beamlet width and spacing that are not feasible. Despite the potential for low performance, short dies are sometimes used to obtain a more uniform thin film transistor (TFT) (for example, small grains allow for more efficient averaging of grains located in/near the channel region of the TFT). It is especially important for active array organic light-emitting devices. In addition, occluded grains produced by grains that do not fully extend the width of the wide column will result in poor device performance.

Another subject of the aforementioned secondary illumination SLS process is distortion. The lens used to project the light member has aberrations, such as astigmatism, which can cause beam distortion. Especially from the center, the beam distortion of the crystalline film is changed to be noticeable. Figure 4F depicts beam distortion formed using the dual array mask of Figure 4A. For example, the beam 1200 is gradually tapered toward the lower right corner of the 4Fth image. In the secondary irradiation SLS, as shown in FIG. 4G, the first pulse 1210 and the second pulse 1220 overlap by about 50% in the secondary irradiation region. Local distortion between overlapping segments of the secondary illumination region can vary. For example, if the lower portion of the second array (right side) of the beam 1200 is skewed due to distortion, the overlap between the second beam array of the first laser pulse 1240 and the first beam array (left side) of the second laser pulse 1230 This will result in uneven centerline spacing of the resulting secondary illuminating material. As shown in Fig. 4H, the line spacing among the beams is not uniform along the vertical scanning direction. For example, the centerline spacing at the top of the scan is fairly equal, and the midline spacing at the lower portion of the scan is not. Therefore, the microstructure of the lower portion is similar to the microstructure of Figure 4E.

Non-periodic pulse SLS

The non-periodic pulse SLS provides a method for the crystallization process to more robustly overcome problems such as poor beam overlap due to platform shake and/or image distortion during subsequent illumination.

This system uses non-periodic laser pulses, which are non-equidistant pulses in the immediate domain. In one embodiment, the system utilizes coordinated trigger pulses from a plurality of laser sources (a single laser source having multiple laser cavities (eg, tubes)) to generate non-periodic laser pulses, thereby generating a series of Pulses that are closely spaced in the time domain. A plurality of laser sources can be configured as a single laser system. The laser system is a computer control system that uses computer control technology and one or more laser cavities to generate one or more laser beams. Each laser beam corresponds to a laser source. Each of the laser beams can be produced by an independent laser or a laser cavity contained in a laser system.

Figure 5 shows an example outline of a non-periodic laser pulse. The y-axis represents the pulse intensity and the x-axis represents the time. Figure 5A depicts the periodic pulse rate of the laser, which can be used in a conventional secondary illumination SLS process. The laser repetition rate produces a laser pulse pattern that is evenly spaced in the time domain. FIG. 5B shows the example of the non-periodic pulse in which the second pulse 500 is excited in a time close to the first pulse 510. Next, the third pulse 520 is excited at a time interval different from the interval between the first pulse 510 and the second pulse 500. Figure 5C depicts an embodiment of different laser power (energy density) for two lasers. The film thus irradiated will experience non-periodic pulse intensity and uneven illumination energy. Since the time interval between the first pulse 510 and the second pulse 500 is very short, as shown in FIGS. 7B-7B, the areas illuminated by the first pulse 510 and the second pulse 500 are more overlapped. In addition, each laser can generate pulses at a fixed repetition rate.

The delay range between the first pulse 510 and the second pulse 500 is less than half the time interval of the first pulse 510 and the third pulse 520. In some embodiments, the time interval of the first pulse 510 and the second pulse is less than 1/10, or less than 1/12, or less than 1/100 of the time interval of the first pulse 510 and the third pulse 520. The delay between the first pulse 510 and the second pulse 500 can range from about 3 microseconds to about 1 millisecond, from about 5 microseconds to about 500 microseconds, preferably from about 8 microseconds to about 100 microseconds.

For example, the delay is as short as a few microseconds (as in the case of a platform speed of 40 cm/s and a displacement of 3.5 [mu]m, the timing is about 8.75 microseconds). If the platform speed is as high as 60 cm/s, the timing is about 5.83 microseconds. In the n-time irradiation process, that is, in a process in which more than two lasers illuminate a specific area (for example, 3, 4, 5, or n times of irradiation of a specific area), the amount of overlap is large. The n-irradiation SLS process is described in U.S. Patent Application Serial No. 11/372,161, the entire disclosure of which is incorporated herein by reference. For example, in n illumination processes, the timing can be about 5 microseconds, or even 3 microseconds. Since the lateral growth rate is as high as about 10 micrometers per second, the film is laterally crystallized in less than about 5 microseconds (μs) when a 6 micron wide region is melted with a pulse having a full width at half maximum (FWHM) of about 0.3 microseconds.

In some embodiments, the displacement exceeds 3.5 [mu]m. Therefore, the delay can be from ten microseconds to 50 microseconds, or even more than 100 microseconds, and possibly hundreds of microseconds. The upper limit can be approximated, but not equal to the repetition rate of two 600 Hz lasers at 1200 Hz: 833 microseconds. For example, for an overlap of 70%, the delay is 500 microseconds. However, if two 300Hz lasers are used, the delay is 1 millisecond.

Tools having multiple laser cavities (e.g., tubes) have been previously described, (1) increasing pulse energy by simultaneously triggering and subsequently combining multiple pulses, and (2) triggering different tubes by delay and subsequent bonding The pulse duration is extended as described in U.S. Patent No. 7,364,952, the entire disclosure of which is incorporated herein by reference. In other words, the pulses can be combined to provide a modified single melt and crystallization cycle. The difference in non-periodic pulse SLS is that it is a pulse that utilizes different lasers in individual melting/crystallization cycles. However, since the pulse time domain is close enough, the platform still effectively overlaps when traveling at high speed.

Figure 5 shows a non-periodic pulse pattern using two closely spaced laser pulses or a "column" of laser pulses; however, more closely spaced pulses, such as 3-5, may be used, corresponding to 3 - 5 laser or laser chambers. In this embodiment, if more closely spaced pulses from different lasers are used, such as laser beams from two different laser energy sources or two different laser carriers of the same laser energy source, the target area The corresponding irradiation is performed more times so that the crystallized region has an extended crystallizing range. For example, n pulses from n laser sources are closely spaced such that a single region will be n times illuminated after a single scan. In a secondary illumination SLS, the beams may have similar widths, but the spacing between the two may be increased to accommodate more illumination. Moreover, the amount of overlap between the crystal regions (corresponding to the individual melting regions) may be greater than 50% (or 1 x lateral growth length), and the crystal grains thus formed will be more than the secondary irradiation process (the grain length is limited by the pulse of the pulse train) Quantity) The resulting grain length. Long grain materials are beneficial for high performance TFTs.

The two consecutive pulses of the pulse train do not need to have the same energy density. For example, if the film still has heat due to the first pulse, the second pulse can have a lower energy density. Similarly, high energy densities can be used to compensate for changes in optical properties caused by the first pulse (amorphous absorption is slightly better than crystallization). Considering the above two effects and other factors, the energy density of the second pulse can be appropriately selected. As shown in Figure 5C, the first laser pulse and the second laser pulse have different energy densities.

System for performing non-periodic pulse SLS

One method of performing aperiodic pulse SLS uses multiple laser sources, such as dual laser sources. Figure 6 shows a system for SLS using a dual laser source. Figure 6 is similar to Figure 1, except that Figure 6 has a second laser 110' and a computing configuration or computer system 600 for controlling two laser excitations and platform movements. Computer system 600 provides computer readable media and computer readable commands to control platform position and to activate laser pulses. The system also includes a plurality of projection lenses whereby multiple sections of the film are scanned simultaneously. A system that is capable of simultaneously scanning a plurality of sections of a film is described in U.S. Patent No. 7,364,952, the disclosure of which is incorporated herein by reference. Although the system and method use a dual laser source, additional lasers may be employed. Other methods of performing aperiodic pulse SLS include operating a high frequency laser in burst mode and/or with a beam interceptor. These two embodiments will be described in detail later. In addition, the system can incorporate an interference based assembly to perform the function of generating a beam like a mask.

The non-periodic laser pulse pattern is preferably obtained by shifting a plurality of lasers of the same repetition rate by offset. There is now a technique that utilizes a single laser to form a non-periodic laser pulse pattern, but is inefficient. In one technique, the mechanism for triggering a laser of a particular repetition rate is modified to produce a non-periodic pulse sequence with alternating short and long time intervals between consecutive pulses. A laser, such as an excimer laser, has a maximum output power that increases with repetition rate until a certain optimal pulse rate at which subsequent power begins to drop begins. In other words, when the optimum pulse rate is exceeded, the maximum energy that the pulse can have will decrease rapidly. Therefore, for a particular laser with a specific maximum pulse energy, shortening the time interval between two consecutive pulses reduces the pulse energy, especially after a short time interval.

In another technique that utilizes a single laser to form a non-periodic laser pulse pattern, the non-periodic pulse pattern is obtained from a single laser that operates in a high power/pulse rate mode, such as a repetition rate of several kilohertz to 10 kHz, suitable for providing downtime in short sequences (such as fast burst continuous laser pulses). Example laser systems to which the methods and systems are applicable include high frequency lasers, such as lasers developed by Cymer (located in San Diego), and are used in laser crystallization tools from TCZ Pte. Ltd. (in Singapore), And diode excited solid state lasers, for example from JENOPTIK Laser, Optik, Systeme GmbH and for laser crystallization tools from Innovavent GmbH. However, compared to lasers with high pulse energy, such as those taken from Coherent Inc. (Santa Clara, Calif.), these high frequency lasers have lower pulse energy and produce smaller pulse sizes.

Film 199 can be an amorphous or polycrystalline semiconductor film, such as a tantalum film. The membrane can be a continuous membrane or a discontinuous membrane. For example, if the film is a discontinuous film, it can be a lithographic patterned film or a selectively deposited film. If the film is a selectively deposited film, it may be a film of chemical vapor deposition, sputtering or solution treatment, such as inkjet printed ruthenium-based ink.

Full area non-periodic pulse SLS

7A and 7B illustrate a non-periodic pulse SLS process using a vertical mask 700 (Fig. 7A). The vertical mask 700 includes a slit array 710 that is vertically positioned (eg, aligned with the vertical scanning direction), optionally having a beveled edge. Slit 710 transfers and shapes the laser beam to produce a plurality of beams of similar shape. The other part of the mask (non-slit) is opaque. It should be understood that the illustrated mask is merely illustrative, and that the size and aspect ratio of the slit and the number of slits are substantially variable and are related to the predetermined processing speed, the energy density required for the film of the melted illumination region, and the available pulse energy. . Generally, the aspect ratio of a particular slit width to length may vary, such as 1:5 to 1:200 and 1:5000 or above. In other embodiments, the mask is a dot mask, the background is transparent, and the center "dot" is opaque. Further details of the dot matrix mask can be found in U.S. Patent No. 7,645,337, the entire disclosure of which is incorporated herein by reference.

As described in the previous secondary illumination SLS, Figure 7B depicts an exemplary membrane that has been illuminated with two sets of double laser pulses, with the first set of double laser pulses appearing intensively, experiencing delay, and then the second set of double laser pulses. Intensive appearance. The process includes at least four illumination steps, wherein the two illumination steps correspond to pulses from a primary laser and the second illumination step corresponds to pulses from a secondary laser. These steps are as follows: When the film is moved in the -x direction and scanned in the +x direction, (1) the first illumination corresponds to the first group of beams (dashed line) formed by the primary laser and masked by the 7A pattern. a second pulsed region 711; (2) a second illumination corresponding to a region 712 illuminated by a first pulse from a secondary laser and patterned by a first set of beams (solid lines) (3) a third illumination corresponding to a region 713 illuminated by a second pulse of a third laser beam (dashed line of the gray region) from the main laser and masked by the 7A image; and (4) fourth illumination Corresponding to an area 714 illuminated by a second pulse from a secondary laser and masked by a solid shape (solid line of the gray area) of Figure 7A. A first secondary illumination crystallization region 715 is created where the first and second illumination regions 711, 712 overlap. A second secondary illumination crystallization region 716 is created where the third and fourth illumination regions 713, 714 overlap.

The first and second crystalline regions 711, 712 and the third and fourth crystalline regions 713, 714 overlap by more than about 50% when the sample is scanned (preferably at a fixed platform speed). Preferably, the first and second crystalline regions 711, 712 and the third and fourth crystalline regions 713, 714 overlap by more than about 70%, greater than about 90%, greater than about 95%, or greater than about 99%. The first illumination of the corresponding region 711 melts the thickness of the entire region; the molten region then rapidly crystallizes laterally from the solid edge into a laterally crystalline region. The second illumination generated by the first laser beam spans the unirradiated region between the individual beam regions of the first set of beams and overlaps the first crystalline region 711. Upon cooling, the crystal of the second region grows from the edge of the second molten region to a crystal grain extending substantially in the x direction (parallel scanning direction). The amount of overlap can be from greater than 50% to about 99%, and the amount of overlap is selected to crystallize the entire region with two laser pulses. The film region completely crystallized in this manner is referred to as "secondary irradiation crystallization region". In this example, illuminating the first crystalline region 711 and then illuminating the second crystalline region 712 will form a first secondary illuminated crystalline region 715. Next, the second crystallized region 713 and the fourth crystallized region are irradiated to form a second secondary irradiated crystalline region 716. If there are more than two laser pulses in the pulse train, the amount of overlap is chosen such that the entire region is crystallized in the number of pulses in the pulse train.

The maximum amount of overlap between the first secondary illumination crystallization region 715 and the second secondary illumination crystallization region 716 is such that the first beam of the second pulse is exactly between the first and second beams of the first pulse. The maximum amount of overlap corresponds to the minimum displacement of one of the half beam spacings of the vertically aligned beams. If the beam is tilted perpendicular to the alignment (as described above), meaning that it is not oriented in the vertical scanning direction, the minimum displacement is half the beam spacing divided by the cosine of the inclination. In the n-th irradiation process (as described above), the first beam of the second pulse is positioned close to the center line of the first beam of the first pulse, with a larger amount of overlap. If the overlap between the first pulse and the second pulse is small, the first and second secondary illumination crystallization regions 715, 716 are narrower. Less overlap will have a "wing" that abuts the first and second secondary illumination crystallization regions 715, 716, wherein the "wing" is illuminated only by a single non-overlapping beam.

Figure 7C depicts an alternate overlap mode in which the second pulse 1110 (solid line) is positioned 1.5 times the beam pitch of the first pulse 1100 (dashed line). The amount of overlap between the first pulse (corresponding to the primary laser) and the second pulse (corresponding to the secondary laser) (corresponding to the secondary illumination region) may be from about 70% to about 99%. As shown in Fig. 7C, less overlap will result in a smaller secondary illumination crystalline region 1120. The low overlap and the long delay between pulses are beneficial for sufficiently cooling the film after the first pulse and before the second pulse.

The second pulse energy density can be adjusted separately by using a small overlap amount method or as described above. In addition, less overlap is beneficial to mitigate the effects of uneven energy density of the beam. As a process that relies on complete melting of the membrane, SLS is quite immune to typical energy density changes between pulses to pulses, or between segments of the pulse. A change in energy density causes a slight change in the width of the area illuminated by a single beam. In the secondary irradiation process, the change in energy density causes a slight change in the amount of overlap between the molten regions, thus changing the microstructure formed. Preferably, a portion of the film is illuminated at a low energy density of one pulse without exposure to a low energy density of another pulse. For example, if a small segment of the beam has a low energy density due to optical system defects, it is preferable to increase the displacement between the two pulses so that part of the film is not illuminated twice by the low energy density section of the beam.

In operation, the platform continues to move the film in the x direction to produce a pulse scan direction as indicated by arrow 720 of Figure 7B, such that the long axis of the slit of the 7A mask is substantially perpendicular to the scan direction. As the film moves, the laser produces pulses at a specific frequency (eg, 300 Hz) that is masked and shaped. The membrane velocity and the excitation offset of the laser pulses of the two lasers are selected such that when the platform moves, the subsequent laser pulses illuminate the overlapping regions 711, 712 of the membrane.

The film velocity and the repetition rate (frequency) of the first and second laser pulses determine the position of the secondary illumination crystalline region on the subsequently formed film. In one or more embodiments, the first and second secondary illumination crystalline regions 715, 716 also overlap at region 715. Therefore, when the film is scanned in the x direction, the entire film surface will crystallize. If the regions 711, 712 only shift half of the beam spacing (as shown in FIG. 7B), the overlap between the regions 715, 716 will be as small as the overlap between the beams, which is a horizontal growth length of 0 in the secondary illumination SLS. Up to 1 time. The amount of overlap between the regions 715, 716 can be reduced to the amount of beam overlap between the rightmost side of the region 712 and the leftmost region of the region 713. The amount of overlap between the first and second secondary illumination crystallization regions may be from about 0.5 μm to about 3 μm.

As described above, with the two independent lasers, the amount of overlap between the first and second regions 711, 712 and the third and fourth regions 713, 714 of Fig. 7B can be increased. The primary laser excites the pulses to crystallize the first and third regions 711, 713. The secondary laser excites the pulses to crystallize the second and fourth regions 712, 714. The pulse excitation is triggered, for example, by a computer control system. At a particular fixed platform speed, the extent to which the first and second regions 711, 712 are overlapped using two lasers is, for example, greater than the degree of overlap caused by the use of a laser at the current laser frequency. It should be noted, however, that the system and method do not focus on the use of multiple laser sources, but rather must produce non-periodic laser pulses. As noted above, lasers with high laser repetition rates do exist and are operable to provide downtime between fast bursts of laser pulses. Developing laser power and frequency can increase productivity and increase the commercial appeal of this approach.

Tilt scanning with non-periodic pulse SLS

In some embodiments, it is beneficial to define the crystal growth toward a slightly tilted TFT channel when the TFT array is subsequently fabricated on the film. If the TFT is aligned in the direction of the parallel array and/or the edge of the active matrix device or film, the diagonal beam can be used, for example, to perform the tilting process (see the polycrystalline TFT uniformity caused by the microstructural misalignment (Polycrystalline TFT) Uniformity Through Microstructure Mis-Alignment, U.S. Patent No. 7,160,763, the entire disclosure of which is incorporated herein by reference. Figures 7D and 7E illustrate the y-axis tilt of the beam relative to the film. Fig. 7D shows that the tilt angle is smaller than that of Fig. 7E, as shown in Fig. 7E, such that there is a large overlap between the first illumination and the second illumination.

The angle of inclination can range from 0 degrees to about 90 degrees. Assuming that the beam is at a specific tilt angle (eg, an angle α relative to the vertical y direction (ie, the direction of the vertical scanning direction)), a specific time delay between consecutive pulses can be calculated to provide a moving distance equal to d = 0.5 × (λ / cos α) Where λ is the beam spacing.

Taking a slope of 75 degrees and a beam width and a pitch of 5.5/1.5 μm (i.e., λ = 7.0 μm) as an example, as shown in Fig. 7D, the moving distance is about 13.5 μm. At a scan speed of 10 cm/s, there is a 135 μs delay between this corresponding continuous pulses. Tilting 45 degrees allows TFTs that align with vertical or horizontal displays or panel edges to have the same TFT uniformity. For example, the double secondary irradiation process may be performed by tilting 45 degrees with respect to the first heavy secondary irradiation and then performing secondary irradiation at an inclination of 135 degrees, that is, vertical first secondary irradiation. For example, when the display design is rotated 90 degrees from the previous assumption, the tilt angle may also be greater than 45 degrees to approximately 90 degrees (eg, near vertical). Although the tilt angle affects the overlap between the regions of the continuous column pulse processing (the smaller the angle, the larger the amount of overlap), in all cases, the amount of overlap between the scan and the scan remains at half the beam width. The tilted beam can be used for the full area and selective area crystallization process, as will be explained later.

Once the film has been completely scanned in the x direction, the shadow beam can be shifted in the y direction to scan the rest of the film. As shown in FIG. 7B, in addition to the overlap region 745 between the secondary illumination regions 715, 716, an overlap region 750 is also created between the first scan 730 and the second scan 740. Therefore, the beam edge is located in the overlapping area. Next, as with the overlapping illumination of the conventional single scan and the secondary illumination SLS as shown in Fig. 4C, it is necessary to properly overlap the beam edges to ensure the continuity of the microstructure. As mentioned above, this involves the use of beam edge processing techniques to ensure that the long axis of the grain is oriented substantially perpendicular to the beam centerline. However, in horizontal alignment, in the case of a non-slope beam, when the next pulse is generated in the overlap region 745, one end of the beam naturally overlaps its opposite end. When using a tilted beam, one end of the beam needs to overlap the opposite end of the other beam depending on the beam length and tilt angle. Therefore, the timing of the pulses is such that the center lines of the beam edges overlap exactly. Beam tilt and angle can be optimized to minimize the amount of overlap of the beam edges.

In the case of non-horizontal beam alignment, the beam edges are still present at the top and bottom of the patterned beam shown in overlap region 750. In order to ensure the continuity of the microstructure between scanning and scanning, that is, to ensure the different regions formed by the full edge scanning, it is also necessary to overlap the edge regions appropriately, even if the beam center lines overlap, and the beam inclination and length are selected to produce a minimum overlap. In order to accurately edge the overlap region 750, platform synchronization is required to control the laser pulse.

The variation in pulse position in the X direction generally results from inaccuracies in pulse timing and changes in platform velocity, which are, for example, sinusoidal. The overlap between pulses is affected by positional changes. The inaccuracy of the pulse timing is usually small and mostly caused by jitter, which corresponds to the inaccuracy of the pulse triggering electronic device. The jitter impact level can be in the order of nanoseconds or more. The jitter causes a slight shift in the pulse position on the membrane and is negligible for this application. Taking a pulse delay of 10 ns as an example, when the platform speed is 20 cm/s, the trigger only causes the sample to shift by 2 nm. The change in velocity causes the pulse position shift on the film to be small as well, and is similar to the gradual shift in the case of shaking. Therefore, closely locating the two pulses will help to reduce the effect of variations on the uniformity of the microstructure.

Beam distortion

The method and system of the present invention also mitigates the effects of beam distortion. In the non-periodic pulse SLS system and method, since the amount of overlap between the first pulse and the second pulse in the secondary illumination region is greater than about 70%, between the first pulse and the second pulse of the secondary illumination region The overlapping portions are closer to the beam path segments, so the degree of distortion is more similar. The final crystalline film is clearly unaffected by distortion. The 7F-H diagram shows the same distortion as the beamforming shown in the 4F-H diagram. Further, the beam 1300 in the lower right corner of the 7Fth figure has been deformed. Figures 7G and 7H illustrate a non-periodic pulse SLS process, which is used, for example, for the 7B map regions 711, 712. Note that FIG. 4F illustrates a vertical alignment mask, and FIG. 7F illustrates a horizontal alignment mask. However, in the example examples of the 4F-H and 7F-H diagrams, the x and y directions have the same degree of distortion, so they affect the vertically aligned beams in the same manner as the horizontally aligned beams. Measuring the beam centerline during the non-periodic pulse SLS process shows that the 7F distortion does not affect the midline regularity (Fig. 7H), nor does it affect the grain boundaries. This benefit results from the close separation of the beam paths between the overlapping portions of the first and second pulses, so that the optical distortion between the two is similar.

The aperiodic SLS systems and methods described above can be applied to a full area crystalline film. For example, aperiodic SLS can be used to scan a plurality of relatively closely spaced TFTs over a large area of the film.

Selective region crystallization using non-periodic pulse SLS

In some embodiments, the non-periodic pulse sequence is used to selectively crystallize specific regions, such as pixel TFTs or circuits of active matrix devices such as displays or sensor arrays. In an embodiment of selective area crystallization (SAC), there is no overlap between the first and second secondary illumination crystalline regions, such as between regions 715, 716 shown in Figure 7B. For example, FIG. 8 illustrates that the film 820 has closely spaced TFTs 825 and is scanned in a non-periodic pulse SLS process with no overlap between the first secondary illumination region 830 and the second secondary illumination region 840. This process implementation uses the same mask as in Figure 7A. Similar to the embodiment of Figure 7B, the film includes at least four illumination steps to form two secondary illumination crystalline regions: a first secondary illumination crystalline region 830 corresponding to a first pulse from the primary and secondary lasers, respectively, and Corresponding to the second secondary illumination crystallization region 840 from the second pulse of the primary and secondary lasers, respectively. The illumination step for generating the secondary illumination crystallization regions 830, 840 is as follows: when the film is moved in the -x direction, (1) the first illumination corresponds to the region 811 illuminated by the first pulse from the main laser; (2 a second illumination step corresponding to a region 812 illuminated by a first pulse from a secondary laser; (3) a third illumination corresponding to a region 813 illuminated by a second pulse from the primary laser; and (4) The fourth illumination step corresponds to a region 814 that is illuminated by a second pulse from a secondary laser. In one or more embodiments, the mask/beam size for the SAC is selected after two pulses (or n pulses) to form one or more fully crystalline regions, and each crystalline region is large enough to accommodate the matrix At least one node or circuit of an electronic device.

Compared with the embodiment of Fig. 7B, only the first and second crystal regions 811, 812 overlap each other, and the third and fourth crystal regions 813, 814 overlap each other. In this embodiment, there is no overlap between the first secondary illumination region 830 and the second secondary illumination region 840. Therefore, the platform holding the sample can be moved at a high speed to increase the interval between the first and second secondary irradiation regions 830, 840 to match the periodicity of the matrix type electronic device. Speeding up the platform can dramatically increase overall processing throughput. For example, in a pixel array of a display, the density of the electronic device is very low, for example, a pitch of several hundred micrometers or more, such as more than 1 mm or more, so that by crystallizing only these regions, the yield can be greatly increased. Thus, for a particular laser pulse rate, the platform can move at a faster rate to achieve a selected area on the fully crystallized film. Example yield values for SAC non-periodic pulse SLS systems can be found in the "Examples" section of this application. The increased production of non-periodic pulsed SACs can make large panel production as required for large TV manufacturing more competitive, such as the eighth generation panel (~2.20 x 2.50 ^m2 ).

A single scan process using non-periodic pulses will place non-periodic pulses on the film where the overlap between pulses in a particular region increases and the overlap outside this region decreases. Non-periodic laser pulses can be placed in a single scan using non-periodic laser pulses and changing the scanning speed to have a low scanning speed during processing of a particular area and a fast scanning speed between specific areas. For example, the use of optical devices to quickly redirect pulses to specific areas can also be accelerated and decelerated quickly. The optical device can include a beam steering element, a fast mirror or an oscillating mask. The implementation of a single-scan SAC SLS process is closely related to the optical device, so it is better to use a non-periodic pulse system. Moreover, its lack of non-periodic pulses can reduce the advantage of platform wobble related errors.

Another single-scan SAC process utilizing periodic laser pulses involves splitting each patterned beam into two or more patterned segments, each of which is large enough to crystallize a particular region and at a distance such that multiple segments are simultaneously Overlap multiple specific areas. The scan is performed at a speed at which the sample travel distance is equal to an integer multiplied by the pitch, such that one segment of the pulse now overlaps with the region previously processed by another segment of the pulse. By appropriately designing the beam pattern of each segment, the second illumination provides a lateral extension of the crystal of the first illumination growth. Forming a segment by blocking (shadowing) a portion of the beam will result in a large separation between the segments and is therefore wasteful. More specifically, the beam splitting technique can be used to redirect a portion of the beam onto the same or a different optical path. The single-scan SAC SLS process does not have the advantage of closely overlapping partially patterned beams that mitigate the effects of beam distortion. Moreover, its lack of non-periodic pulses can reduce the advantage of platform wobble related errors.

As noted above, selective region crystallization involves crystallizing only specific regions of a matrix type electronic device or circuit. The position of the crystalline region needs to be aligned with the node location of the matrix type electronic device or circuit. The sample alignment step can be achieved in accordance with various techniques. In one technique, sample alignment can be achieved quickly using a crystallization system that is more capable of locating a sample in a manner that reproducibly positions its other processing steps in the fabrication of the electronic device. A common method is, for example, when the panel is provided with a reference point or an alignment mask, which is detected before crystallization and aligned for the crystallization process. This sample alignment method is commonly used in lithography procedures to fabricate thin film transistors that cover different features of the device for sub-micron accuracy. SAC sample alignment does not need to be as precise as lithography. For example, the sides of the crystalline region may be several microns or 10 microns or more larger than the particular region.

In another technique, the position of the crystalline region is detected prior to fabrication of the electronic device to establish sample alignment. The method of achieving may be to detect an area of the electronic device to be set itself, or to detect an additional crystalline area optimized for alignment, such as a reference point. The use of a projection crystallization system is beneficial for sample alignment. The system can be used to make a fiducial or alignment mask on a film or substrate for subsequent sample alignment. The patterned beam can be used to fabricate well-defined features that can be used for panel alignment in at least one of the earliest subsequent lithography steps, followed by fiducials defined by lithography. The benefit of complete melting and associated lateral growth is that there are connected protrusions in the vertical long grain boundaries, which can be observed by a dark field microscope. Further, the phenomenon of changing from an amorphous phase to crystallization can be observed by a microscope, which is caused by a change in optical properties.

The system for sample alignment can include an automated system for detecting a reference point and aligning the sample relative to the reference point to a known location. For example, the system can include a computing configuration to control the moving and responsive optical detector that detects the reference point on the film. The optical detector is, for example, a charge coupled device (CCD) camera.

Figure 9 illustrates a film 910 treated in a SAC process. In Fig. 9, the pixels 920 of the film 910 are horizontally positioned, but in the seventh and eighth figures, they are vertically positioned. In Fig. 9, a plurality of secondary irradiation regions 930, 940, 950, and 960 are superposed on the TFT 970 of the pixel 920.

Compared to the aforementioned SLS method, the beam width in the non-periodic pulse SAC SLS tends to be small; it only needs to be as wide as the width of the region to be crystallized. Therefore, excess energy can be used to increase the beam length. Using a large diameter projection lens and/or splitting the beam into individual optical paths, a long beam length can be obtained whereby multiple regions of the film are simultaneously crystallized during beam pulse scanning. Increasing the length of the treatment zone during a single scan reduces the number of scans required to fully crystallize the film. The scanning speed is actually smaller than the traditional SLS, which adds another advantage of the freely designed platform scale. The non-periodic pulse SLS has the advantages of random design scale because of the tightly spaced pulses in the time domain and more robustly overcome the problems of deviations such as platform shaking and beam distortion.

The advantage of using aperiodic pulse SLS to maximize SAC requires optimizing the size of the patterned beam and optimizing the layout of the pixel TFT or circuit. Improved pixel TFT and circuit design, for example, can reduce the width of the area to be crystallized. As shown in Figure 9, optimization involves rotating the sub-pixel configuration by 90 degrees and rearranging the layout of the pixel TFTs and circuitry. Taking a 55-inch display having a pixel pitch of 660 μm as an example, the width of the electronic device is at most about 300 μm. Therefore, the film of 660 μm requires only 300 μm to be crystallized. In addition, the two regions to be crystallized in adjacent crystal columns can be brought together, so that a single set of beams can be used to crystallize the entire region, and then a large region is skipped to the next set of TFT/circuit regions. In the case of a liquid crystal display with a simple pixel circuit (usually only a single TFT), the area to be crystallized is narrower, so further narrowing the beam width and subsequently extending the beam length throughout the wide diameter lens and/or a large number of projection lenses becomes less Attractive.

The SAC needs to enhance the crystallization process by selectively crystallizing only specific regions and omitting the membrane regions therebetween. Similarly, the ability to illuminate selected regions eliminates the need for precise scanning to scan overlapping beams to fully crystallize regions, eliminating the need for edge-processed overlapping beam edges. The beam length closely matches the size of the corresponding TFT or circuit to be crystallized. The beam length is chosen to contain an integer number of TFTs or circuits. There is some space left between adjacent pixel TFTs or circuits that does not require crystallization. This space is for example a node for the long electrodes to connect to the active matrix.

In addition, the beam can be subdivided into groups of beams along its length, each of which corresponds to the size of the pixel TFT or circuit. Figure 10A discloses a mask 1010 for the SAC crystallization mode. The ends of the beams do not need to overlap, so the mask of Figure 10A has a rectangular edge. The mask 1010 can be used in conjunction with the film 1020, as shown in FIG. 10B, which includes spacer pixels 1030 each having a TFT 1040, wherein the slit size of the mask is selected to be slightly larger than the size of the TFT 1040, so that only these are scanned. The area will crystallize.

By placing the slit only on the corresponding film on the mask where the TFT or circuit is to be formed, the thermal load on the system light member, especially the projection lens, can be reduced. As shown in FIG. 6, the projection light member 195 is located downstream of the mask 170. Therefore, if the mask blocks more light, the projection lens will receive less light, thus reducing overheating.

In SAC, the beam pulse can be narrowed, and in some embodiments, the amount of overlap between the first and second pulses is less than 50%, while the next pulse time is still quite long. The time interval of each pulse is still very short, which is to maintain the advantage of non-periodic scanning SLS. In some SAC embodiments where the overlap between some of the first and second pulses is limited while the secondary illumination crystallization regions do not overlap, the airfoil on either side of the regions overlaps the airfoil of the adjacent secondary illumination crystalline regions.

Example

As described above, the non-periodic pulse SLS crystallized by the selective region has a high yield. Assuming a 1.2 kW laser with two tubes each illuminated at 600 Hz (1 J/pulse) and two 5 mm x 0.3 mm pulse sizes with two 50 mm field projection lenses, 22 pixel scans can be processed for pixel spacing. For a display of 660 microns and made of a 8th generation panel, for a total of 22 x 250 cm / (600 Hz x 660 μm) + 21, or about 160 seconds, each round trip time is 1 second. The resulting scanning speed is approximately 40 cm/s. If a 30 second load and unloading time is taken, the throughput is 30 days x 24 hours x 3600 seconds x (1/160 + 30) seconds, or about 13.6k panels/month. Also assume that the uptime of the device is 85%, then the output is 11.6k panels/month.

Suitable for pulse generation when using a 1.2 kW laser made from two tubes of different phases (ie combined into a periodic 1200 Hz pulse sequence) and a 5 cm x 0.6 mm pulse size (single 50 mm field of view projection lens) for conventional SLS The platform speed of 50% overlap is 36cm/s, and the number of scans is doubled (ie 44 times). Therefore, the processing time of each panel by the conventional SLS exceeds twice the processing time of the SAC non-periodic pulse SLS instance described above.

Although the present invention has been disclosed in the above embodiments, it is apparent that those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. For example, it should be understood that the manner in which the film is advanced in a selected direction may be an embodiment in which the laser beam is held stationary and the film is moved relative to the laser source, and the film remains stationary and the beam is moved.

110, 110’. . . Laser

120. . . Delayer

125. . . Attenuation board

130, 140, 160. . . mirror

135. . . telescope

145. . . Homogenizer

155. . . Beam splitter

165. . . lens

170. . . Mask

195. . . Light piece

198. . . platform

199. . . membrane

210, 215. . . Slit (array)

211-214. . . region

216. . . boundary

217, 240. . . spacing

221. . . Polysilicon/region

223-225, 227, 229. . . region

228. . . Section

231-234. . . Crystal column

235-238. . . Grain boundaries

239, 241-244. . . crystallization

260. . . width

265. . . length

340, 340', 345, 360, 380. . . region

365. . . Grain

370. . . Grain/area

400. . . Mask

402, 404. . . Slit (array)

410. . . membrane

415. . . Pixel

420. . . Circuit

430. . . electrode

440, 450, 460, 461, 461a, 470, 471, 471a. . . region

460’. . . line

465. . . arrow

480. . . Overlapping part/area

490-493. . . region

490’-493’. . . Grain boundaries

490A-490C. . . Grain

500, 510, 520. . . pulse

600. . . computer system

700. . . Mask

710. . . Slit (array)

711-716, 745, 750. . . region

720. . . arrow

730, 740. . . scanning

811-814, 830, 840. . . region

820. . . membrane

825. . . TFT

910. . . membrane

920. . . Pixel

930, 940, 950, 960. . . region

970. . . TFT

1010. . . Mask

1020. . . membrane

1030. . . Pixel

1040. . . TFT

1100, 1110. . . pulse

1120. . . region

1200, 1300. . . Beam

1210, 1220, 1230, 1240. . . pulse

The invention will become more apparent and understood by reference to the appended claims.

Figure 1 depicts a system for a continuous lateral crystallization (SLS) process;

Figure 2A shows a mask for the SLS process;

Figure 2B-2D shows the SLS process;

Figure 3 illustrates a secondary illumination scan using a secondary illumination SLS process;

Figure 4A illustrates a mask for the SLS process;

4B-4E illustrates a secondary illumination scan of a pixel array using a secondary illumination SLS process;

Figure 4F-4H illustrates beam distortion formed by the mask of Figure 4A;

Figure 5A is a diagram showing the relationship between time and pulse energy in a conventional secondary illumination SLS process;

FIG. 5B is a diagram showing relationship between time and pulse energy in a secondary illumination SLS process for selective propulsion according to an embodiment of the invention; FIG.

5C is a diagram showing the relationship between time and pulse energy in a secondary illumination SLS process for selective propulsion according to an embodiment of the invention, wherein the energy of the second pulse is greater than the first pulse;

6 is a diagram of a system for a non-periodic pulse SLS process in accordance with an embodiment of the present invention;

7A is a vertical mask for a non-periodic pulse SLS process according to an embodiment of the invention;

7B is a diagram showing a secondary illumination scan in a non-periodic pulse SLS process according to an embodiment of the invention;

7C is a diagram showing an alternative overlapping manner in a non-periodic pulse SLS process according to an embodiment of the present invention;

7D and 7E are diagrams showing a non-periodic pulse SLS process in which a beam is inclined with respect to a film edge, in accordance with an embodiment of the present invention;

7F-7H are diagrams showing distortion of a non-periodic pulse SLS process according to an embodiment of the invention;

8 is a diagram showing a selective region crystallization non-periodic pulse SLS process according to an embodiment of the invention;

9 is a view showing a film processed by a selective region crystallization non-periodic pulse SLS process according to an embodiment of the present invention;

10A is a diagram showing a mask for selective area crystallization non-periodic pulse SLS process processing according to an embodiment of the present invention;

FIG. 10B illustrates a selective region crystallization non-periodic pulse SLS process in accordance with an embodiment of the present invention.

700. . . Mask

710. . . Slit (array)

711-716, 745, 750. . . region

720. . . arrow

730, 740. . . scanning

Claims (73)

A method of processing a film, the method comprising: illuminating a first region of the film with a first laser pulse and a second laser pulse while advancing a film in a selected direction, each laser pulse providing a shape The light beam has a fluence sufficient to melt the entire thickness of the film, and respectively forms a first melting zone and a second melting zone, which are laterally crystallized upon cooling, wherein the second melting zone crystallizes upon cooling Forming one or more laterally grown crystals as an extension of the one or more laterally grown crystals formed by the first molten region; and irradiating the film with a third laser pulse and a fourth laser pulse a second region, each pulse providing a shaped beam and having a fluence sufficient to melt the entire thickness of the film to form a third molten region and a fourth molten region, respectively, which are laterally crystallized upon cooling And wherein, when cooled, the fourth molten region crystallizes into one or more laterally grown crystals, which is an extension of the one or more laterally grown crystals formed by the third molten region; wherein the first laser pulse A second time between the laser pulse interval of less than half of the first laser pulse and a third time between the laser pulse interval. The method of claim 1, wherein a first laser source generates the first laser pulse and the third laser pulse, and a second laser source The second laser pulse and the fourth laser pulse are generated. The method of claim 2, wherein the first laser source and the second laser source generate pulses at a fixed repetition rate. The method of claim 1, wherein the film continues to advance in the selected direction. The method of claim 1, wherein the first laser beam and the second laser pulse respectively provide a light beam that overlaps the first region of the film, the third laser pulse and the fourth laser The respective beams provided by the pulses overlap in the second region of the film, wherein the amount of overlap of the plurality of laser pulses between the first region and the second region of the film comprises greater than 90% overlap. The method of claim 5, wherein the amount of overlap comprises greater than 95% overlap. The method of claim 5, wherein the amount of overlap comprises greater than 99% overlap. The method of claim 1, wherein the shaping beam is obtained by guiding the laser pulse through a mask. The method of claim 1, wherein the shaped beam comprises a plurality of beams. The method of claim 9, wherein the beams are positioned at an angle relative to an edge of the film. The method of claim 9, wherein the beams comprise a plurality of edge processed beams. The method of claim 1, wherein the shaped beam comprises a pattern. The method of claim 1, wherein the second region overlaps the first region. The method of claim 1, wherein the first region and the second region are separated from each other and separated by an unirradiated region of the film. The method of claim 1, wherein an edge of the film is positioned at an angle relative to the selected direction. The method of claim 1, comprising fabricating an electronic device in each of the first region and the second region of the film. The method of claim 1, wherein the first region and the second region are selected to form a sufficiently large crystalline region sufficient to accommodate a circuit belonging to a node of a matrix type electronic device. . The method of claim 2, wherein the first laser source and the second laser source are two different lasers. The method of claim 2, wherein the first laser source and the second laser source are two separate laser cavities within a laser system. The method of claim 1, comprising a fourth pulse disposed between the second pulse and the third pulse, such that a time interval between the fourth pulse and the second pulse is greater than the fourth pulse A time interval between the third pulse is short. A film treated according to the method of claim 1, wherein the film comprises the first region and the second region. An electronic device comprising a film processed according to the method of claim 1 wherein the film comprises the first region and the second region. An electronic device as claimed in claim 22, comprising a thin film battery A crystal is disposed in each of the first region and the second region of the film. A method of processing a film, the method comprising: when advancing a film in a selected direction, the plurality of first beams provided by the plurality of first laser pulses are irradiated throughout the plurality of first regions of the film; a plurality of second light beams provided by the laser pulses are irradiated throughout the plurality of second regions of the film; and wherein a fluence of each of the first light beams and the second light beams is sufficient to melt a film of one of the illumination regions The entire thickness, when cooled, the irradiated region is then laterally crystallized into one or more laterally grown crystals, and wherein an amount of overlap between the first region and the second region of each group is greater than a first group of the first An amount of overlap between an area and the second area and a subsequent set of the first area and the second area. The method of claim 24, wherein, in cooling, a first set of second molten irradiation regions are crystallized into one or more laterally grown crystals, which is formed by a first set of first molten regions. An extension of a plurality of laterally grown crystals. A method of claim 24, wherein a primary laser source produces the first laser pulses and a primary laser source produces the second laser pulses. The method of claim 24, wherein in a set of the first area and the second area, an overlap between the first area and the second area is greater than 90%. The method of claim 24, wherein in a set of the first region and the second region, an overlap between the first region and the second region is greater than 95%. The method of claim 24, wherein in a set of the first region and the second region, an overlap between the first region and the second region is greater than 99%. The method of claim 24, wherein an overlap between the first group of the second region and the most recent second group of the first region is less than 10%. The method of claim 24, wherein an overlap between the first group of the second region and the most recent second group of the first region is less than 1%. The method of claim 24, wherein an overlap between the first group of the second region and the second group of the first region is zero. A method of claim 24, wherein the first set of the second area and the second set of the first area are spaced apart from each other and separated by an unirradiated area of the film. The method of claim 24, wherein the primary laser source and the secondary laser source generate pulses at a fixed repetition rate. The method of claim 24, wherein the film continues to advance in a selected direction. The method of claim 35, wherein an edge of the film is positioned at an angle relative to the selected direction. The method of claim 24, wherein the beam comprises a plurality of beams. The method of claim 37, wherein the beams are positioned at an angle relative to an edge of the film. The method of claim 24, wherein the first region and the second region are selected to form a large crystalline region large enough to accommodate a circuit belonging to a node of a matrix type electronic device. . A system for processing a film using a non-periodic laser pulse, the system comprising: a primary laser source and a primary laser source for generating a laser pulse, respectively; for generating a shape from the laser pulse a device for mounting a film on a substrate; a platform for moving the film relative to a beam of light to generate a direction of propagation of the laser beam pulse on a surface of the film And a computer for processing a platform synchronized laser pulse command such that a first region of the film loaded into the mobile platform is provided by a first group of one or more laser pulses from the primary source a shaped beam of illumination, having a second region of the film illuminated by a second set of one or more shaped beams from a laser pulse of the secondary source, and a third region of the film a third set of one or more shaped beam illuminations provided by one of the primary sources, wherein the processing command is for moving the film relative to the beam pulses in the direction of propagation to illuminate the first region, The first Region and the third region, wherein the first region and a second region is irradiated between the overlap amount is larger than the amount of overlap between the irradiating a second region and the third region. A system of claim 40, wherein the device comprises a mask. A system as claimed in claim 40, wherein the device comprises an optical control system. A system as claimed in claim 40, comprising a projection lens for transmitting the laser beam pulses. A system as claimed in claim 43 includes a plurality of projection lenses for generating the laser beam pulses. A system of claim 44, wherein each of the projection lenses produces a laser beam to process a portion of the film. The system of claim 40, wherein an overlap between the first area and the second area is greater than 90%. The system of claim 40, wherein an overlap between the first area and the second area is greater than 95%. The system of claim 40, wherein an overlap between the first area and the second area is greater than 99%. The system of claim 40, wherein an overlap between the second region and the third region is less than 10%. The system of claim 40, wherein an overlap between the second region and the third region is less than 1%. The system of claim 40, wherein an overlap between the second region and the third region is zero. The system of claim 40, wherein the second region and the third region are separated from each other and separated by an unirradiated region of the film. The system of claim 40, wherein the primary laser source and the secondary laser source generate pulses at a fixed repetition rate. A system of claim 40, wherein the film continues to advance in a selected direction relative to the laser source. A system of claim 40, comprising a means for positioning the film relative to at least two built-in reference points. The method of claim 38, wherein an edge of the film is positioned at an angle relative to the selected direction. The method of claim 38, wherein the one or more shaped beams are positioned at an angle relative to an edge of the substrate. The system of claim 40, wherein the size of the region formed by the amount of overlap between the first region and the second region is It is selected to form a sufficiently large crystalline region sufficient to accommodate a circuit belonging to one of the nodes of a matrix type electronic device. A method of treating a film using a non-periodic laser pulse, the method comprising: when advancing a film in a selected direction, generating a first plastic from a first laser source at a first time Forming a beam, and irradiating a first region of the film with the first shaping beam to form a first melting region, which is laterally crystallized into a first group of crystalline regions upon cooling; at a second time, from a first time a second laser beam of the laser source generates a second shaped beam, and the second shaped beam illuminates the first region of the film to form a second melting region which crystallizes laterally upon cooling a second set of crystalline regions; and at a third time, a third shaped beam is generated from a third laser pulse of the primary laser source, and the second shaped region of the film is illuminated by the third shaped beam Forming a third melting region, which is laterally crystallized into a third group of crystalline regions upon cooling; wherein a time interval between the first time and the third time exceeds a time interval between the first time and the second time Twice. The method of claim 59, wherein the melted regions formed by the first shaped beam and the second shaped beam are positioned to provide laterally extending crystal growth. The method of claim 59, wherein a fluence of each of the first beam, the second beam, and the third beam is sufficient to melt the entire thickness of the film of a illuminating film region. The method of claim 59, wherein the film continues to advance in a selected direction. The method of claim 57, wherein an edge of the film is positioned at an angle relative to the selected direction. The method of claim 59, wherein a first beam of the first laser pulse and the second laser pulse are overlapped in the first region of the film, wherein the first laser pulse and the second The amount of overlap between the laser pulses is greater than 90%. The method of claim 62, wherein the amount of overlap between the first laser pulse and the second laser pulse is greater than 95%. The method of claim 62, wherein the amount of overlap between the first laser pulse and the second laser pulse is greater than 99%. A method of claim 59, wherein each shaped beam is obtained by directing the laser pulse through a mask. A method of claim 59, wherein each shaped beam comprises a plurality of beams. The method of claim 59, wherein the shaped beam comprises a beam formed by a dot pattern mask. The method of claim 59, wherein the first region and the second region are adjacent to each other. The method of claim 59, wherein the first region and the second region are separated from each other and separated by an unirradiated region of the film. The method of claim 59, wherein the first beam, the second beam, and the third beam are positioned at an angle relative to an edge of the film. The method of claim 59, wherein one of the first region and the second region is sized to form a sufficiently large crystalline region sufficient to accommodate a circuit belonging to a matrix type electronic device.