KR20180014439A - Fiber laser-based systems for uniform crystallization of amorphous silicon substrates - Google Patents

Abstract

A system is provided for crystallizing amorphous Si (a-Si) panels by either partial melting laser annealing (LA) or sequential lateral solidification (SLS) annealing processes. The system includes at least one single transverse mode (SM) quasi-continuous wave (QCW) fiber laser source that emits pulsed harmonic beams; A beam conditioning assembly positioned downstream of the fiber laser source and configured to deform the harmonic beam such that the harmonic beam has desired divergence and spatial dispersion characteristics; A beam velocity and profile assembly operative to provide a conditioned harmonic beam having a desired intensity profile at a desired scanning rate in an object plane; A beam imaging assembly for imaging the conditioned harmonic beam in the object plane onto the image plane along at least one beam axis with the desired reduction so that the width of the conditioned harmonic beam is reduced to a narrow line width; And a panel handling assembly operative to provide a relative position and velocity between the imaged narrow line width beam and the panel to inspect each position of the a-Si panel at least twice in exposure time.

Description

Fiber laser-based systems for uniform crystallization of amorphous silicon substrates

The present disclosure relates to fiber laser-based methods and systems for manufacturing flat panel displays. In particular, the disclosure relates to a fiber laser system for annealing an amorphous silicon panel by a harmonic laser beam to produce a substantially uniform polycrystalline silicon display, and to a method of operation of the system according to the invention.

The flat panel display (FPD) manufacturing environment is one of the most competitive and complex technologies in the world. In general, these techniques continue to require compact products that have FPDs and are characterized by high resolution, bright and large displays, low power consumption and fast video capability, and, of course, low cost.

Film transistor (TFT) technology is the basis for FPD fabrication, which can be a high resolution, high performance liquid crystal display (LCD), or an organic light emitting diode (OLED). In the early days of TFT technology, the display circuitry was fabricated on a thin opaque layer of amorphous silicon ("a-silicon or a-Si") and arranged in the backplane across the layer to correspond to each pixel. Each pixel contains a large number of crystalline particles, each formed with a specific particle region and orientation.

Thereafter, the a-Si has two orders of magnitude greater carrier mobility than the a-Si carrier mobility and substantially improves the aperture ratio and pixel resolution. And is at least partially replaced by poly-silicon (p-Si), which reduces the pixel size. As a result of this nature of poly-Si, portable / mobile electronic devices now feature high resolution flat panel small displays.

There are two fundamentally different approaches for converting a-Si to poly-Si through crystallization (annealing). One is a thermal annealing (TA) approach and the other is a low temperature poly-silicon annealing (LTPS) approach of particular interest. In the latter, a-Si is initially thermally treated and converted to liquid amorphous Si, which is then maintained in the molten state for a specified period of time. A temperature range that is sufficient to maintain the molten state is selected to allow the initially formed poly-crystallite to grow or crystallize. After the crystallization step is complete, the surface is cooled to induce a solidification phase of the processed material. The LTPS approach is based on two general methods - excimer laser annealing (ELA) or partially molten LA and sequential side coagulation (SLS) - SLS is of particular interest here and is also a common- U.S. Patent Application No. 14 / 790,170 (US '790), which is incorporated by reference in its entirety.

In contrast to conventional ELA, the SLS method involves melting the entire thickness of the a-Si film by a beam from an excimer laser operated at 3xx nm wavelength. As a result, a crystallization front is grown from opposite sides of the molten film. In other words, growth is lateral. The crystal grains generated laterally can be elongated to a large horizontal dimension. The latter is advantageous because the electron mobility increases as the particles grow larger. However, despite the advantages and disadvantages of each method versus other methods, both SLA and partial annealing (EL) methods are viable options.

Historically, excimer lasers used in both LA and SLS processes have led to the annealing of TFT flat panel displays. Excimer lasers provide a wide range of processing power with an average range of processing power up to 300 W or more, energy greater than 1 J and pulse widths from 10 to 250 ns. The excimer also transmits UV light of wavelength (3xx nm) directly absorbed into a-Si without additional frequency conversion.

The pulse frequency of the excimer laser is relatively low. Within the applicant's knowledge limit, this is significantly lower in standard ELA without exceeding 6 kHz in the SLS process. The relatively low frequency of such a standard ELA can account for a plurality of irradiation needs at each location because the duration between subsequent pulses is such that the excited atoms over time lose their mobility ) Time constant. With respect to SLS, at the KHz frequency resulting in a large energy, the excimer requires multiple gas changes during the day's operating period, which is not suitable for mass production. Many of the above and other disadvantages of excimer lasers are not unique to fiber lasers.

The need for the use of a fiber laser-based annealing system operable to provide a substantially uniform p-crystalline structure (p-Si) by using both SLS and partial annealing (LA) exist.

400:1)). 일차적인 스캐닝은 전형적으로 단축의 방향으로 실시되나, 장축 스캐닝이 배제되는 것은 아니다.The SLS process requires a line beam at the target and the major axis is several orders of magnitude larger than the minor axis (e.g., 2 mm major axis / 5 μm minor axis

400: 1). Primary scanning is typically performed in the direction of the short axis, but long axis scanning is not ruled out.

2 mm의 라인 빔 길이를 허용할 수 있다. 특정 관계는 단축의 세기 프로파일에 따라 달라진다. 예를 들어, 상단부 모자형(hat) 단축 프로파일은 가우스 단축 프로파일보다 긴 라인 빔을 허용할 수 있을 것이고, 모든 다른 매개변수는 동일할 수 있다. 그럼에도 불구하고, 전술한 값들은 고려 중인 다양한 매개변수들 사이의 상대적인 관계를 나타내는 것이다.The dimensions of the line beam are determined by three parameters: the desired width of the short axis (the desired poly-Si particle size and the function of the short axis intensity profile), the desired fluence of the target (J / cm ² ) By the pulse energy. For example, a 5 [mu] m wide line with a required impact of 100 [mu] J pulse energy and 1 J / cm < ² >

A line beam length of 2 mm may be acceptable. The specific relationship depends on the strength profile of the short axis. For example, the top hat short axis profile would allow a longer line beam than the Gaussian short axis profile, and all other parameters could be the same. Nevertheless, the above values represent the relative relationship between the various parameters under consideration.

The panel to be annealed with such a line beam is several orders of magnitude larger than the length of the line beam that can be achieved in an SLS with a separate burst mode fiber laser. It would be necessary to stitch the beams from separate or multiple lasers together to achieve an effective continuous poly-Si particle structure.

The partial LA process requires significantly larger impact requirements and larger average power. However, due to the beam width, which in part is greater than 5 microns larger than the 1 to 2 micron line width in the SLS, there is no sealing problem.

A system according to the present invention, which is unique in the LA process of both SLS and both SLS and which solves the above and other problems, enables the implementation of a selected method for annealing a large panel. Aspects of the disclosed system include scanning / stepping, multiple laser compatibility, essential speed and accuracy, auto-focus compatibility, thermal management, active alignment and thermal management along each axis, summarized below.

The disclosed system for crystallizing an amorphous Si (a-Si) panel by a partial melting laser annealing (LA) or sequential lateral solidification (SLS) annealing process, according to one aspect of the disclosure, At least one single transverse mode (SM) quasi-continuous wave (QCW) fiber laser source that emits pulsed harmonic beams at a pulse repetition rate. The system further includes a delivery system including a beam conditioning assembly positioned downstream of the fiber laser source and configured to deform the harmonic beam such that the harmonic beam has a desired divergence and spatial dispersion characteristics. The delivery system further includes a beam velocity and profile assembly operative to provide a conditioned harmonic beam having a desired intensity profile at a desired scanning rate within the object plane. The delivery system is further configured to cause the conditioned harmonic beam in the object plane to be imaged onto the image plane along the at least one beam axis with the desired reduction so that the width of the conditioned harmonic beam is reduced to a narrow line width of at least 1 占 퐉 in the image plane. ≪ / RTI > The system comprises at least two times a-Si with an exposure time of at least 100 ns each to provide conversion of a-Si into a polysilicon (p-Si) structure having a uniform particle width of 1 mu m or less, And a panel handling assembly operable to provide relative position and velocity between the imaged narrow line width beam and the panel to inspect each position of the panel.

According to another aspect, the system described in one embodiment further comprises a plurality of SM QCW fiber laser sources that emit respective combinable beams.

In another aspect, a system of any of the above aspects is configured to convert a high-ratio Gaussian harmonic beam to a flat-to-top harmonic and includes a beam fragmentation and recombination system, a beam re-apodization system , A beam combining system, and a beam cropping system.

Another aspect of the system according to the present invention of any of the above embodiments relates to a beam fragmentation and recombination system selected from a fly's eye or a bi-prism optical arrangement.

In another embodiment of the system according to the invention disclosed in any of the above embodiments, the flies are imaged or non-imaging homogenizers.

Another aspect of a system in accordance with the present invention of any of the above aspects is a system configured to superimpose and intersperse a plurality of harmonic beams to create a central, ≪ / RTI >

In another aspect of the system according to the present invention of any of the disclosed aspects, the beam combining system is operated to superimpose a plurality of harmonic beams. One of the superimposed beams is everted so that the resulting harmonic beam is homogeneous in the major axis direction.

In a system of any of the above aspects according to another aspect, the beam combining system consists of a polarized beam combiner or field lens combiner or a diffracted beam combiner or fly eye.

In a system of any of the foregoing aspects and the following aspects, a beam re-apodization system includes at least one or a plurality of beams that convert a high-ratio Gaussian harmonic beam from at least one beam axis into a flat- Cylindrical non-cylindrical optical element.

In a system of any of the foregoing and following aspects, the beam speed and profile system is designed to produce a conditioned harmonic with desired velocity, such that the imaged narrow line width beam produces a homogeneous and continuous line of crystallization without sealing, And a scanner operative to provide a beam.

In each of the systems described above and in the following embodiments, the scanner is selected from a rotating mirror or acousto-optical deflector or galvanometer.

In a further aspect of the disclosed system of any of the foregoing and following aspects, the beam imaging assembly focuses a conditioned harmonic beam having a desired intensity profile at a desired scanning rate along a short beam axis direction onto a first mask And a focusing lens. The first mask has a cutting knife for forming the object plane and for sharpening the edge of the beam in the major axis direction and an objective lens located downstream of the first mask and adjacent to the panel.

According to a system of any of the foregoing and following aspects, the beam imaging assembly further comprises a second mask positioned between the first mask and the objective lens and configured to vignette the residual inhomogeneity of the lines of crystallization .

According to another aspect of the system described in any of the foregoing and following aspects, the beam imaging assembly includes an anamorphic lens that provides different hope reduction along the vertical beam axes of the conditioned harmonic beam with the desired intensity profile lens arrangement.

A current embodiment of a system of any of the foregoing and following aspects is directed to a beam imaging assembly comprising two spaced masks that are anamorphic and provide different shrinkage along each vertical beam axis and have different object planes .

Another aspect according to the present invention of any of the foregoing and following aspects is directed to a beam imaging assembly having a proximity mask configured to define a desired length of a beamline on a panel such that the proximity mask limits edge diffraction Away from the panel.

The system of any of the foregoing and following aspects also includes a panel handling assembly having a support for supporting the annealed panel such that the panel can be displaced along orthogonal XY planes relative to the fixed beam imaging assembly do.

Another aspect of the system according to the present invention of any of the foregoing and following aspects is directed to a beam imaging assembly that is displaceable along orthogonal XY planes and configured to be stationary with respect to the beam imaging panel, To the panel handling assembly.

In yet another aspect of the system of the present invention described in any of the foregoing and following aspects, the panel handling assembly is configured such that the panel can be displaced on one of the XY planes and the beam imaging assembly is moved on the other of the XY planes And a supporting portion for supporting the annealed panel so as to be displaced.

A system of this aspect relating to any of the above and the following aspects consists of a SM QCW fiber laser source that can be mounted in a fixed position relative to a displaceable beam imaging system or displaceable therewith.

The system of any of the foregoing and following aspects further includes an autofocus system, a beam profiler, and a MURA measurement system.

In such an embodiment, the system of any of the embodiments described above and in the following embodiments consists of a fly-eye homogenizer having a delay step glass element to eliminate the coherence effect.

Another aspect of the system according to the present invention of any of the foregoing and the following aspects is that the residual heterogeneity region of the p-Si structure effectively scatters residual inhomogeneity and reduces the mura to a predetermined reference range, And a dithering system operative to dither the narrow line width beam onto the panel so as to be at different positions along the line.

Another aspect of the disclosed system described above and in any of the following aspects 24 is an optical system comprising a panel or any suitable component downstream of the object plane or an optical component of a beam delivery system such as a lens or mirror, To an optical component along a beam path in the direction of a conditioned harmonic narrow width line beam during an annealing process, or to a dithering system operated to oscillate a mask forming a target plane.

In accordance with another aspect of the invention disclosed in any of the above-described aspects, the system is configured to generate successive lines in both the SLS and AL processes with one or more passes.

In another aspect of the disclosure as described in any of the above embodiments, the system according to the present invention is operated to provide interdigitation of multiple beams after more than two passes.

In another aspect, a system according to the present invention of any of the foregoing and following aspects is configured to provide pulse picking using mechanical scanning, acousto-optic or electro-optical methods.

The above and other aspects of the disclosed system will become more apparent from the following detailed description taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a general, highly schematic diagram of a system according to the present invention.
Figure 2a is a variation of the system according to the invention of Figure 1;
Figure 2a is another embodiment of the system according to the invention of Figure 1;
Figure 3 is a view of the beam conditioning / homogenization and beam profiling subassembly of the system according to the invention of Figures 2a and 2b.
Figure 4 is a view of the beam imaging subassembly of Figures 2a and 2b.
Figure 5 is a view of the panel handling sub-assembly of Figure 1;
Figure 6 is an optical schematic of a beam homogenization subassembly with a beam polarizing combiner.
Figure 7 is a graphical representation of the operating principle of the homogeneous subassembly of Figure 6;
Figures 8 (a) through 9 (b) are additional schematic representations of the operating principle of the homogenization subassembly of Figure 6, respectively.
Figures 10a-c are respective arrangements operated to combine multiple beams.
Figures 11 (a) - 11 (c) are vertical, side and top views, respectively, of another configuration of the beam homogenization subassembly.
Figs. 12 (a) to 12 (c) show the thermal deformation of a single line to be crystallized by the laser beam.
Figure 12 (a) shows the general operating principle of the scanning subassembly.
Figures 13 (b) to 13 (d) show a harmonic laser beam having a different intensity profile.
Figures 14A-14C are diagrams of a system using polygon scanners and polygons, respectively.
15 (a) to 15 (b);
16A and 16B;
17 (a) and 17 (b);
18 (a) and 18 (b);
19 (a) and 19 (b);
20 (a) to 20 (d);
21 (a) to 21 (c)
22; And
23;
24-27.

Embodiments of the present invention will now be described in detail. Wherever possible, the same or similar reference numerals are used in the drawings and the detailed description to refer to the same or like parts or steps. Some of the drawings are in a simplified form and do not have a precise scale. Unless specifically stated otherwise, ordinary and familiar meanings to those skilled in the art of diode and fiber lasers are intended to be given to words and phrases in the specification and claims. The word "coupled" and similar terms do not necessarily indicate a direct and immediate connection, but also include mechanical and optical connections through free space or intermediate elements.

The fiber laser-based system according to the present invention is designed to increase the productivity of a silicon annealing process that includes both standard ELA and SLS and is configured to significantly reduce the manufacturing and operating cost of presently available annealing systems. In the context of SLS, the system of the present invention is configured to output a harmonic pulsed beam of at least 1 탆 width in 3xx and 5xx nm pulsed beams incident on an a-Si panel of all known generation Si panels. As a result, a p-Si crystalline structure having uniform < RTI ID = 0.0 > um-less < / RTI >

 Figure 1 shows a general layout of a modular system 10 according to the present invention that can be used in both SLS and LA processes to anneal small and large a-Si panels. Regardless of the particular annealing method, the system 10 in accordance with the present invention is a substantially diffraction-limited laser pulse type (e. G., ≪ RTI ID = 0.0 > Is based on a fiber laser source 12 that produces a beam. Assembly 14 is configured to control the divergence and beam size for additional homogenization and scanning sub- The homogenization and scanning subassembly 16 is configured to control the intensity and velocity of the conditioned beam in the mask plane. The following sub-assemblies 18 provide a conditioned beam on the a-Si surface in the hope of reduction through a panel handling subassembly 20 that is operated to provide patterns of different displacements between the annealed panel and the beam delivery system And is operated to image. The modular system 10 in accordance with the present invention features several configurations of each of the above-described sub-assemblies listed above specifically as disclosed below.

Figure 2a shows a modular system 10 mounted on a movable console 22 surrounding an IR pump laser, a cooling system, control circuitry and other peripheral components enabling the operation of the fiber laser source 12 do. The system 10 consists of a gantry machine having an inverted U-shaped bracket 24 and a base 26 mounted on the console 22. While the beam imaging sub-assembly 18 is stationary, the stage 20, which supports the panel to be laser processed, can be moved in the illustrated configuration so that the surface of the workpiece is laser processed according to various morphological patterns, In the XY plane. Alternatively, as shown in FIG. 2B, both the panel and the beam-imaging subassembly 18 can be moved within respective planes, respectively. Another configuration that is particularly advantageous for a sixth to eighth generation panel allows the panel to remain intact while the beam imaging subassembly is moved within the X-Y plane. The system according to the present invention has an optical configuration that can again have various configurations that operate with all possible variations of the displacement between the panel and the beam delivery assembly without substantially any structural changes.

The fiber laser source 12 is disclosed in co-pending, co-owned US '790 application. Briefly, in addition to a laser pump that can be located within the console 22, a laser source 12 is configured. The fiber laser pump operates with a substantially diffraction limited, quasi-continuous system (QCW) that outputs a pump beam within a fundamental wavelength range of 1 μm in the kHz to MHz repetition rate range. The pump beam is coupled into the laser head 28, which is configured with beam guiding optics and a harmonic generator. Depending on the number of frequency / wavelength conversion stages, a harmonic beam of about 532 nm wavelength or about 355 nm wavelength is output for propagation along the beam path through the sub-assembly of system 10. A single-mode or low-mode (SM) pump source 12 is operated to output packets of pulses at a pocket repetition rate (PaRR) of up to 2 MHz and a packet duration between 50 and 500 ns. The pulses in each packet are output at frequencies varying from about 80 MHz to 200 MHz. The source 12 is configured to output a pulsed beam having a profile of substantially Gaussian intensity as a burst of pulses or a beam of successive pulses. The beam of successive pulses in combination with at least one micron-wide line beam on the target, the controllable effect, the incremental stage speed and other beam and system parameters is at most 1 micron, but preferably less than 1 micron But also a p-Si structure with a short coherence time of about 20 to 30 ps with a uniform particle length as short as 2 microns.

Referring to FIG. 3 with FIG. 2, an output harmonic beam having M ² that is equal to or close to 1 is further propagated through the beam conditioning subassembly 14. The configuration of the beam conditioning subassembly is tailored specifically to the needs of the homogenization subassembly and / or the scanning subassembly located downstream of the subassembly 14.

Because the system 10 shown in Figures 2-5 includes a homogenization subassembly that is operative to convert the Gaussian intensity profile into a flat top or top hat profile, the beam conditioning subassembly 14 includes an upstream and downstream collimator . The harmonic fiber laser beams of the previously disclosed wavelength are typically elliptical with large aspect ratios and Gaussian intensity variances, respectively, in the long and short axes. Accordingly, the upstream collimator component includes a cylindrical lens configured to provide a harmonic beam having a desired size in a short axis. This is for illustrative purposes as a Gallilean telescope having a negative and positive cylindrical lens 30. Similarly, a downstream collimator including a negative and positive cylindrical lens 32 provides a harmonic beam having a desired size in the major axis direction. In this regard, the collimated harmonic beam is conditioned for further homogenization.

An elliptical (but not circular beam excluded) harmonic beam with a Gaussian intensity profile is susceptible to interference when superimposed. The coherence properties also exclude the diffraction homogenization solution due to speckle related phenomena. Therefore, coherence should be somewhat mitigated.

Both the SLS and LA processes require line beams with sufficient homogeneity along the length of the line. Although the SLS process is less sensitive to homogeneity to single digits than the ELA annealing process, it still must have adequate homogeneity. As the intensity profile is homogenous, the process window is more open to pulse-to-pulse energy variations and focus depth.

The homogenization subassembly 16 solves the coherence problem and provides a line beam on the target with a substantially uniform intensity distribution along the length of the beam line. The short axis may have a size of less than five wavelengths and due to the diffraction resolution (point spread function) limitations, there is a limit to how homogeneous such axes can be made with physically rational optical components. There are not many advantages that can be obtained from the homogenization line width, except for very wide beam widths (e.g., greater than 10 micrometers).

Conceptually, homogenization is based on two standard techniques: fly-eye homogenizer as used in system 10 of FIGS. 2-5, and beam fragmentation and recombination techniques used with bi-prism. The principles of fragmentation and recombination techniques are well known to those of ordinary skill in the art. If a Gaussian-like laser beam, similar to that produced in the system according to the invention, is combined after being divided into a plurality of beams and then changing the profile of one or more divided beams, a homogenous beam is generated along at least one axis can do. The fly eye homogenizer overlaps multiple pieces of the beam and requires a beam with very low spatial coherence. Otherwise, they suffer from severe speckle and other interference related phenomena.

Fiber lasers are generally not considered candidates for fly eye homogenization due to their generally large coherence. However, through experimentation, it has been found that the laser source disclosed herein and in US '790 has a sufficiently short coherence time so that a section of the retarder is added to the individual piece to ensure coherent time is exceeded at the overlap position . Flies eye homogenizer is an option for these lasers. Thus, the disclosed fly-eye and bi-prism homogenizer successfully exploits the disclosed QCW lasers.

The homogenization subassembly 16 of FIGS. 2-5 provides a homogenized line beam in the plane of the mask 54 (FIG. 4). Which includes a first array of cylindrical lenslets 34 that divides the incident Gaussian beam into respective beamlets. The beamlets then impinge on each retarded glass 36, 38, 42, which provides optical retardation between such beamlets as a unit to minimize interference and thereby alleviate the coherent effect of the laser beam , Which leads to the formation of a flat-top strength profile. The flat-top beam may not ideally have a uniform intensity. Accordingly, optionally, the sub-assembly 16 may further have a one-dimensional mask 40 with an opening that further propagates only the most desired homogeneous portion of the homogenized beam down the path. Then, the homogenized beam is incident on the condenser lens 48.

Two main types of fly eye homogenizer: there are both visualized and non-animated flame homogenizers that are all included in the system according to the present invention. The term "imaging" has many meanings because the basic mechanism is the imaging of the first array 34 of lenslets into a mask or object plane. Structurally, the imaging homogenizer also includes a second array 44 of lenslets of FIG. 3 positioned between the phase converters 36, 38 and the condenser lens 48. The lenses of the second array 44 and the focusing lens 48 image the individual field diaphragms onto the mask / object plane. This type of homogenizer requires precise alignment of the optical axes of the two lens arrays, the focusing lens and the incident beam.

A less complex version of the optical integrator is referred to as a non-imaging homogenizer. The non-imaging homogenizer consists of a single, first lens array 34 followed by retarded glasses 36, 38 and 42 and a condenser lens 48. Similar to the imaging homogenizer, the lens array 34 is configured so that the harmonic incidence passes the interference beam through the phase converter, before they pass through the condenser lens 48 and are superimposed at the homogenization position located in the rear focal plane of the condenser lens Into a beamlet. The intensity pattern in the homogenization plane is related to the spatial frequency spectrum generated by the lens array. In order to obtain good flat-top uniformity using a non-imaging homogenizer, the lens array must disperse light at uniform intensity within the desired angular-spectral image.

 Referring to FIG. 4, the focused homogeneous beam passes through a beam imaging subassembly 18 configured to transmit the homogenized beam to the image plane on the surface of the panel in the hope reduction multiple. The homogenized beam is first projected and focused onto the mask 54 by the focusing lens 50 in the direction of the short axis of the beam. The mask 54 consists of a blade that crops the edges of the homogenized beam projected in the longitudinal direction. This mask plane is then re-imaged onto the objective lens 60 at some optimized shrinkage with edge resolution limited by the numerical aperture of the imaging system. For example, a reduction of 10x or 30x reduces the sensitivity to pointing stability. However, if the imaging system is out of focus, due to diffraction from the sharp edges of the mask, a diffraction pattern will appear at the end of the line beam. As with any imaging system, the depth and resolution of the focus are inversely proportional to each other so long as the imaging is of diffraction-limited resolution. An optional mask 56 that accommodates the line beam can be viewed as a vignetting aperture that eliminates the residual inhomogeneity of the previously sharpened edge.

5, a reduced line beam having a desired degree of uniformed intensity and width is coupled to an objective lens 60 and illuminated before switching on an a-Si glass panel that rests on stage 62, And is additionally impacted by a turning mirror 58. Panels, especially large panels, are not ideally flat. The use of the auto-focusing assembly 64 allows the desired focal distance between the spherical or anamorphic objective 60 to be maintained, thereby controlling the desired uniform range of beam intensity of the line beam on the target. Depending on both the system implementation and the uniformity of the panel thickness, it may be necessary to implement dynamic autofocus, and individual beams may have their focal planes continuously adjusted to maintain homogeneous poly-Si particle structure throughout the panel area . Whether autofocus is required and the required accuracy will depend on the depth of focus of the line beam optical delivery system.

Often, by observing the annealed panel, iridescence caused by the periodic microstructure generated during the crystallization process can be confirmed. The non-uniformity of the microstructures likewise causes variations in the intensity known as "mura" which is believed to originate when the two annealed panel areas are sealed together in the beam longitudinal direction. A sub-assembly 68 for measuring the morphological characteristics of the annealed panel is disclosed in U.S. Patent Application No. 62334881, which is incorporated herein by reference in its entirety. The presence of mura may require automatic rebalancing of the system 10. More particularly, the stand alone type measurement system 68 is operated to measure the characteristics of light generated by an independent laser source and diffracted from the panel in real time. Such characteristics may include diffraction efficiency, diffraction angle, and heterogeneity of the polarization state of the diffracted light. Providing one or more feedback control loops, when the measured parameters or parameters of the mura exceed a predetermined range, allows real time rebalancing of any of the subassemblies described above.

Another measurement subassembly is configured as a beam profilometer 70 disposed anywhere along the beam path downstream of the homogenization subassembly. The beam gauge 70 may be a camera-based beam profiling system comprised of a camera and analysis software. Often, depending on the task, such systems need to be used with beam attenuation or beam sizing aids. The advantage of camera-based beam profiling is to observe in real time and measure the structure of the laser with high accuracy measurements. If the measured beam profile parameters or parameters are outside a predetermined range, the annealing process is terminated and troubleshooting of the identified malfunctioning sub-assembly begins.

Referring to FIGS. 6 and 7, homogenization of the sub-assembly 16 of the system 10 based on fragmentation and recombination techniques includes a bi-prism. The bi-prism-based subassembly 16 according to the present invention is configured to impart an optical path difference between the two beamlets. The path difference should be set so that the delay is longer than the coherent length / time.

In particular, the preconditioned harmonic circular or elliptical Gaussian beam 80 is propagated through the? / 2 waveplate 82, configured to control the energy split, and is split into two vertically polarized Are further split in an upstream polarizing beam splitter 72 that directs the beamed beams 84 and 86. The beamlet 86 is guided along the longer, retarded path of the sub-assembly 16 including the multiple-conversion mirror 88 polarizing beam combiner 74. The other beamlet 84 is propagated through a single-axis external prism 76, whose exclusion is made and further coupled into the polarization beam combiner 74.

3 ns의 시간차가 존재할 것이다. 150 MHz 반복율의 1.5 ns 펄스의 경우에, 이러한 지연은, 2개의 경로로부터의 분출 내의 펄스가 별개의 시간에 도달하는 것을 보장하기에 충분하고, 간섭은 존재하지 않을 것이다. 도 7에 도시된 바와 같이, 청색 빔렛(86) 및 적색 빔렛(84)은, 시간적인 서로의 중첩이 없이 그리고 간섭이 없이, 3.3 ns의 지연으로 각각의 긴 경로 및 짧은 경로를 통과한다. 동일한 편광의 빔렛들은 6.7 ns 반복율에 상응하는 150 MHz에서 서로간을 따른다. 따라서, 서로 끼워진 빔렛들이

303 ns 분출로 300 MHz 유효 반복율로 출력된다. 만약 2개의 경로 사이의 시간 지연이 펄스 지속시간보다 짧지만 레이저 가간섭성 시간보다 긴 경우에, 간섭이 또한 없을 것임을 고려하여야 한다.For example, if path 86 is one meter longer than path 84,

There will be a time difference of 3 ns. In the case of a 1.5 ns pulse of 150 MHz repetition rate, this delay is sufficient to ensure that the pulses in the ejection from the two paths arrive at a distinct time, and no interference will be present. As shown in FIG. 7, the blue beamlet 86 and the red beamlet 84 pass through each long and short path with a delay of 3.3 ns, without temporal overlap of each other and without interference. Beamlets of the same polarization follow each other at 150 MHz, corresponding to a repetition rate of 6.7 ns. Thus,

303 ns is output with an effective repetition rate of 300 MHz. If the time delay between the two paths is shorter than the pulse duration but the laser is longer than the coherent time, it should be considered that there will also be no interference.

Although this method is certainly simpler than the fly eye, the better homogeneity of the beam can be obtained with the flies eye method, which results in a plurality of lenslets compared to only two beams in the bi-prism method, Because.

Figures 8 (a) and 8 (b) and 9 (a) and 9 (b) illustrate another variation of the homogenization subassembly 16. This type of homogenizer relates to the bi-prism fragmentation and recombination of FIG. 6 and can be generally referred to as a beam combination. In particular, the time slice bi-prism homogenizer extends to beam combining homogenization techniques through the geometric superposition of multiple beams and / or beam fragments, as long as the two pulses in the pulse ejection do not reach a certain position with temporal overlap .

Figures 8 (a) and 8 (b) show four (four) beams 88, 90, 92 and 94 which are overlapped and temporally dotted in order to create a central homogeneous section 96 Respectively. Figure 8 (b) shows four beam overlays where beams 88 and 94 are simultaneous while beams 90 and 92 are spotted. As can be appreciated, the beams do not overlap in time or space. In the context of system 10, this homogeneous section is cropped by the mask and then imaged onto the panel surface.

Figures 9 (a) and 9 (b) show three beams overlap with valgus. Here, the outer beam is distorted so that the majority of the line beams are uniform along the long axis. Such a method allows an extended length of the line beam and lowers the quality of the line suture required in the fiber laser beam used to anneal the large panel, as described further below. Although more effective than the cropping technique of Figures 8 (a) and 8 (b), this technique still discarded the laser power at the ends of the homogenized line beam.

The simplest way to allow a Gaussian beam profile to be converted to a top hat beam profile is to crop the central portion of the beam within the homogeneity requirement. The cropping should be made in the mask (object) plane 54 of FIG. 4, which is then imaged onto the combined object / process (image) plane through the objective lens 60 of FIG. In this way, the objective lens 60 may use an anamorphic cylindrical element with different shrinkage along each axis, or a symmetrical element with a spherical area that provides a constant shrinkage. This method discards most of the beam energy. In this regard, the beam combining method is more efficient than simply cropping the center, homogeneous portion of a single beam, but still has the same problem.

Figures 10A-10C illustrate respective beam combining configurations. 10A shows a system including a polarized beam combiner that receives two linearly p-polarized and s-polarized input laser beams. The input beam propagates along each leg of the system shown, which may comprise a half-wave plate, respectively. Figure 10B shows a beam combining structure capable of angularly combining multiple beams passing through a field lens capable of focusing such beam into a single beam waist. Figure 10c shows a beam combining arrangement in which a plurality of converging beams of different orders collide with a diffracting beam combiner configured to combine the passing beams into a single output beam.

Referring to Figures 11 (a) to 11 (c), the beam homogenization subassembly 16 utilizes an aspheric optical element to remap the apodization of the Gaussian beam to the top hat apodization . The best known example of this type is piShaper. piShaper is a telescope in which the intensity profile is transformed in a controlled manner and one of the basic principles is that the zero wave of the entire system, which distinguishes this type of homogenizer from, for example, fragmentation and recombination- aberration).

As described above, the SLS process absolutely requires homogenization along the long axis. The optimal top hat re-apodization will thus be one axis only or anamorphic. In both cases, a cylindrical lens is required. The illustrated system includes, for example, an anamorphic cross cylindrical lens 98 designed to convert a circular beam into a 1 mm long line beam homogenized by diffraction limited point spread along each axis. These lenses convert the beam intensity profile directly in focus. This method can be used to illuminate a mask plane, which is then imaged onto the process plane through an objective lens that is symmetrical to anamorphic or acetabular areas. In an actual application of the present invention, the use of a single anamorphic lens to transform the beam profile along the long axis is required. This method is not only the input beam profile and divergence but also the concentration and angle-sensitive alignment of the incidence. Any beam propagation using such a method should be able to guarantee a beam concentration of 10 microns and orthogonality of 10 micro radians.

Now that the scanning system and scanning subassembly 16 of the profile is described, it will be appreciated that when a line beam having a particular length and intensity is scanned along the entire length of the desired crystallization line at a specific speed, Homogeneous irradiation can be performed. This method allows a short beam to drag in the major axis direction to create successive long lines of arbitrary length, thereby obviating line sealing. The profile of the beam along the minor axis is less important, but must remain constant along the length of the beam. A top hat or even a supergaussian shortening profile will make more use of laser power possible, but it is not necessary for the process to be effective. The scanning technique is realized by a rotating mirror or an acousto-optical deflector (AOD) of Figs. 16A to 16D, as described below.

Figures 12 (a) and 12 (b) show a general operating principle configuration for implementing a scanning technique. Fig. 11 (a) shows a beam of constant pulses irradiating a long line in the direction of arrow (A). All positions along the line are exposed, for example, to the same top end flat beam (Figure 11 (c)), so that at a particular point in time, the initial portion 101 is completely crystallized. The recently investigated line range 103 is still within the process of crystallization and will be completely crystallized as the panel is further moved along the arrow A and the line range 105 is currently being examined and the range 107 Not investigated. The thermal profile of the line to be crystallized, which is schematically shown in Fig. 11 (b), shows the state of the line ranges 101 to 107 described above.

For a given laser power and line beam width, the required line beam length and scanning speed to achieve the desired effect and exposure time can be determined as follows: A line beam of length L _b and moving speed v Assume the upper hat-shaped line beam of Fig. 11 (c). At this rate, the exposure time is

T = L _b / v.

Thus, in the case of exposure time T and line beam length L _b , the required speed is:

v = L _b / T.

For the target laser power P and the line beam width W _b , the intensity is:

I = P / L _b and _b .

The scanning effect at any point is:

H = IT = PT / L _b and _b .

To summarize the above, for the desired effect H and exposure time T, the required line length and scanning speed are set to be: laser power P and line beam width W _b :

L _b = PT / HW _b

it is easily confirmed that v = P / HW _b .

Yes:

Laser power = 150 W

Line beam width = 5 탆

Required exposure time = 300 ns

Required effect = 0.7 J / cm ² (7,000 J / m ² )

Based on the foregoing, the line beam length Lb = 1.3 mm

Scanning speed = 4,300 m / s.

Figures 13 (a) to 13 (d) conceptually show the scanning configuration. The laser source outputs a harmonic beam that passes through a beam conditioning subassembly that produces a desired beam profile in the mask plane or directly in the image plane after the scanning assembly. 13 (b) to 13 (d), the desired profile is defined by the gauss along both axes 104, the Gaussian / Quasi Gauss along the direction of one axis, And a top hat profile along the direction of both axes as indicated by 108. The top hat profile shown in FIG. If a top hat profile is desired, a homogenization subassembly is required, the configuration of which depends on the laser beam characteristics and the desired profile. The beam is incident on the scanner and the scanning optics to obtain the desired beam profile before passing through the mask plane or before being transmitted directly to the image flat panel.

Figs. 14A-14E illustrate one possible configuration of a beam delivery and scanning subassembly 18 with a rotating mirror, such as a monogon or polygonal polygon 100. Fig. 2, the scanner 100 may be used with a homogenizer or without a homogenizer to illuminate the mask and mounted to the gantry machine instead of the switch mirror 46. [ The plane may be oriented at any angle, such as 45 ^o or 90 ^o, and deflects the harmonic beam along the optical path towards the telescopic cylindrical gallylin diffuser shown in Figs. 14b through 14e. The extended beam then passes through the uniaxial field lens 50, the mask 54 and the switching mirror 58 before being coupled into the objective lens 60.

Other types of scanning-based beam delivery systems include the use of optical solid state deflectors, which are dependent on acousto-optic effects and are additionally referred to as AODs. AOD, which is not well-known to those of ordinary skill in the art, does not include a moving part and thus exhibits a faster deflection rate than a mechanical scanner and is more reliable. AOD is based on periodically varying the refractive index in an optically transparent material, which is induced by propagation of sound waves in the material. Changing the refractive index is a result of the refraction and compression of the material, which leads to a change in the density of the material. This periodically varying refractive index acts similarly to an optical grating, which is moved by the speed of sound in the crystal, which diffracts the laser beam traveling through the material.

In the context of SLS, the panel to be annealed with a line beam is several orders of magnitude larger than the length of the line beam that can be achieved with an individual ejection mode fiber laser. Therefore, it is necessary to seal together the beams from individual or multiple lasers in order to effectively achieve a continuous poly-Si particle structure with a particle size of less than 1 micron and as small as 0.2 microns.

Excimer lasers used for the ELA process have a large energy per pulse with a low repetition rate. This makes such a laser suitable for single-line annealing of large panels, and the line beam encompasses the entire panel width.

However, an ejection mode fiber laser with the same total power output has a pulse energy that is a few orders of magnitude smaller and requires a larger number of repetition rates. The pulse energy is too low to allow the line beam from a single laser to encircle the entire panel width.

For this reason, it is necessary to seal or scan the individual line beams together so that the resulting poly-Si particle structure is continuous across the region of interest. The area of interest may be the entire panel area, or it may be a part thereof.

Also, at very high repetition rates, there may be insufficient time between individual ejections to allow sufficient cooling for SLS crystallization to occur. In such a case, it may be necessary to arrange all the second line beams in the first pass so that there is sufficient cooling for the occurrence of crystallization at each beam position, and then the intervening line beam is passed through the second pass You need to deploy. Alternatively, a pulse picking method or a method of simultaneously scanning in the major axis direction can be implemented. Pulse picking may be used instead of, or in conjunction with, all second lines per pass. Suturing two adjacent lines together in the long axis provides considerable difficulty. Ideally, each line beam will have a perfectly sharp edge, and the edges of adjacent beams will be precisely bounded.

Another possibility is to trim the intensity profile of the end of the beam so that the effective intensity remains homogeneous when adjacent beams overlap. Although there are coherence / speckle problems in the overlapping interference beams, adjacent beams can be spotted so that individual pulses within each ejection do not arrive at the same time.

The following disclosure includes a method of sealing various beam lines for continuous poly-Si coverage. Controlling the beam delivery and panel handling subassemblies can provide a way for various line patterns and individual line beams to be sealed to surround the area of interest.

Referring to Figures 15 (a) and 15 (b), successive lines with 1-D scanning have a separate beam, which is somewhat analogous to the LA continuous line beam, so that the individual beams effectively constitute a continuous line. It is the simplest conceptually used to align. This effective line beam will then be scanned in one dimension along the entire panel as shown in Figure 16A. Depending on the dimensions of the individual line beams, this may result in very tight packing of the objective lens / projection lens and other optical elements, so that mounting and alignment fixation can be an extremely difficult challenge.

Figures 15 (a) and 15 (b) illustrate respective configurations for mitigating the compact filling problem. By placing the fold mirrors 110 near the waist of the individual beams, i.e., close to the image plane, there is sufficient free space between the beams. The individual objective / projection lenses or lenses 60 (Fig. 5) may be sequentially arranged in different orientations to free up space for the fixation of such lenses, in the case of multiple laser beams. The two illustrated arrangements on Figures 15 (a) and 15 (b) respectively show alternating directional folding of individual line beams, and three-way folding lamination. This basic concept can be extended to other configurations to achieve the same goal. The difficulties associated with generating successive lines are primarily associated with alignment, interference interference, autofocus, and mechanical / thermal stability.

0.1 ㎛ 공차까지 서로에 대해서 정렬되어야 한다.The individual line beams must be carefully aligned, both in position and in angle, so that the resulting continuous line beam is sufficiently homogeneous in both intensity and profile to support the annealing process. For the SLS process, the individual beams are aligned along the entire continuous crystallization line length

They should be aligned with respect to each other up to a tolerance of 0.1 mu m.

Some overlap is required where individual line beams meet. The range of superposition will depend on the specific beam profile. Fiber lasers used for SLS processes have large spatial and temporal coherence and are susceptible to interference when superimposed. All of the neighboring individual beams must have a random phase with respect to each other or the individual pulses in each ejection should arrive at distinct times for the neighboring line beams as described above with reference to the t profile and velocity subassembly Pulse ejections must be timed.

Although the individual line beams may be configured to carry the required continuous line beam parameters, the line beams must maintain alignment while continuously processing large area panels. Considering the large dimensions of the eighth-generation panel, for example, due to the differential thermal expansion, even a small temperature difference of 1 占 폚 can cause misalignment of more than 10 占 퐉 over the panel dimensions.

Also, if the ejection repetition rate is too large for the crystallization occurrence in a single pass, it may be required to place all the second ejections in the first pass and then fill the remaining ejections in the second pass.

Finally, the depth of focus of the laser process will be limited, which may cause the panel to have insufficient flatness to meet the required focus depth. In this case, it will be necessary to implement dynamic autofocus for each of the individual line beams.

0.1 ㎛ 의 정확도까지 양 축으로 정렬되어야 한다. 다시, 반복율이 너무 크다면, 순차적인 분출들의 물리적 분리가 요구될 것이다.A further variation of successive lines includes multiple passes as shown in Figure 16B. If the length of a continuous line is limited to a portion of the panel width, the entire panel can be covered with a line beam offset between passes and by using several passes. If the line is ½ panel wide, two passes may be required. 1/3 panel width may require 3 passes, and so on. While this approach facilitates some of the fallopian tubes associated with the entire panel width line beam, there is a fallout associated with maintaining the continuity of the poly-Si particle structure between passes. The ejection in successive passes

It should be aligned on both axes to an accuracy of 0.1 μm. Again, if the repetition rate is too large, a physical separation of sequential sprays will be required.

17A and 17B, instead of attempting to generate a continuous line beam from a plurality of short line beams, the beam can be scanned in one direction and stepped in the other direction to form a continuous Separately spaced individual line beams can be scattered across the panel to provide a poly-Si particle structure. For the sake of brevity, the line beam is scanned in the same direction step by step. Alternatively, it may be scanned in an alternate direction after stepping for each pass. Depending on the number of lasers, the particular characteristics of the lasers, the individual line beam dimensions, and how the individual line beams are generated, the actual number of beams can be from several to several tens. Again, the ejection repetition rate may require physical separation of sequential ejections. The embodiment shown in Figures 16b and 17a and 17b can be combined so that the separate line beams of Figure 17 are each made up of a number of successively seamed individual line beams of Figure 16, have.

The requirement for physically separating sequential spatters may arise due to repetition rate and / or engagement constraints. There are two basic methods for physically separating sequential pulses.

One technique involves multiple passes with increased scanning speed. Here, a single line beam is scanned in the minor axis direction with respect to the panel at a sufficient speed so that individual pulses are physically separated to produce all the second line beams. The successively generated pass is offset in the minor axis direction, so that the missing alternating line beams are disposed.

While this above described technique is most conceptually simple compared to other techniques requiring line beam spacing, it also requires a doubling of the scan speed relative to successively placing the line beams in a single pass. For example, if the laser is operated at 1 MHz and the line beam should be spaced every 2 μm, a single pass would require a scanning speed of 2 m / s, whereas a double pass would require 4 m / s . This is an extremely fast speed for scanning the beam across a large panel with an accuracy of 0.1 mu m level.

If multi-pass engagement is implemented with an engagement ratio greater than 2, then the scanning speed problem is compounded linearly with the engagement ratio.

If the pulse ejection is sequentially separated into different beam lines, it is repeated at a constant coefficient value such that the effective repetition rate for the individual beam lines is reduced by the coefficient. The above example requiring a single beam line of 2 m / s can be modified to, for example, four beam lines of 500 mm / s if the coefficient is four.

If multiple scans are used, there will always be a fallout at the seam between the individual passes, whether a multiple pass continuous line beam, a separate line beam location, or a combination thereof. Maintaining the continuity of the poly-Si particle structure across the seam will be a challenge. The specific requirements for the final device to be fabricated from the SLS annealed panel will define an acceptable seam discontinuity.

If such a requirement is too rigid and can not be met with successive joints, a beam engagement scheme may be implemented and boundaries between the individual beams may be applied across the panel, as shown in Figures 18, 19, 20 and 21 They are staggered. Depending on the degree of engagement, it can be ensured that the device transistor does not have a region larger than a particular partial region of the beam sealing boundary.

Engagement also has the added advantage of separating the placement time of physically adjacent beams on the panel thereby reducing or eliminating the effect of improper crystallization time between pulses due to a large repetition rate.

Referring to Figures 18 (a) - 18 (c), the engagement can be achieved by disposing them offset with individual passes. For example, if two-beam engagement is required, as shown in Figure 19 (b), the scan speed may be determined such that the pulse interval is exactly two line widths. The beam will then be stepped over the panel by half the beam length. The second pass will place the pulse correctly between the pulses of the first pass. The beam will then be stepped again by half the length of the beam, and the third pass will place the beam exactly aligned with the beam in the first pass, as shown in Figure 18 (c).

If three-beam engagement is required, as shown in Figures 19 (a) to 19 (e), the pulses are spaced by three line widths and the step size is one third of the beam length between passes The same process will follow. The number of interlocking beams can be chosen arbitrarily large. This method will be limited by the maximum achievable system scan speed. At a given pulse repetition rate and line width, the required scan speed will increase linearly with the number of interdigitated beams. Engagement automatically eliminates all problems related to repetition rate and crystallization time.

Referring to Figures 20 (a) through 20 (d) and Figures 21 (a) through 21 (c), instead of placing all the pulses individually in one pass at a time, Multiple beams can be simultaneously placed so that engagement occurs within a single pass. This figure illustrates single pass two-beam three-beam engagement. During a single scan, the beams are arranged with respect to each other such that a plurality of beams are engaged. As in the mode for individual pulse placement, the number of interlocked beams is limited only by the practicality of the implementation.

By separating the individual beams in the scanning direction, this method linearly reduces the effective repetition rate with respect to the crystallization time, together with the number of engaged pulses. This method works well in combination with the pulse picking method of Figure 22, as well as reducing the number of passes required to fill the interlocking pattern.

The beam sealing method can be implemented in combination to achieve the p-Si particle characteristics required within the constraints of the laser and system resources. In addition, each of the disclosed techniques and combinations thereof can be implemented with multiple, cooperative laser sources, and also with the pulse picking method described below.

As described above, a large laser repetition rate can result in insufficient time for crystallization between pulses in the SLS. Instead of using multiple passes to fill each scan line with physically separated pulses, the pulses can be picked into separate beam lines with fixed coefficients. Pulse picking is associated with a scanning subassembly 100 that utilizes mechanical (scanning polygons, galvanometers, etc.) as previously described, an acousto-optic method, or an electro-optical method known to the ordinarily skilled artisan.

The pulse picking technique may be implemented in different ways. One approach involves directing the pulse-picked beam to a separate beam line, such that the individual beam lines are then scanned similarly to a single line. This can be realized using two approaches-continuous lines and interlocked line beams-and has the advantage of reducing the effective repetition rate of individual beam lines, but requires multiple beam transmissions per laser.

The first approach allows pulse-picked beams to be delayed and combined with respect to each other, allowing one long homogeneous continuous line to be passed through a single beam transmission. This results in a line beam similar to that achievable with a low repetition rate, higher pulse energy laser. An alternative approach involves engaging, including using a pulse-picked beam to create a multi-pass engagement, as described above, or arranging to create a single pass engaging pattern.

Another way of pulse picking involves long axis scanning with a rotating scanner, such as polygon 100 or AOD shown in FIG. The redirected beam is incident on the proximity mask, where the knife edge defines the length of the beam that illuminates the surface. The line width of the beam is formed using the previously described uniaxial mask with a degree of reduction different from that of the proximity mask. As a result, successive ejections of the pulses produce adjacent, closely spaced lines that are seamed along successive longer lines at ejection repetition rates that are separated along the major axis and effectively reduced with respect to the minor axis. This is different from the line draw technique because the line draw technique is characterized by continuity and obviously requires no suture. A scan along the long axis of the beam, such as a continuous ejection, is successively sealed within the line on the panel.

Notwithstanding all of the above-described arrangements and techniques, the local, persistent heterogeneity region in the line beam can result in patterning within the polycrystalline grain structure. Such a pattern can cause visible irregularities in the finished display, especially in the sealed lines where the patterning will be periodic. One relaxation technique is to place the line beam on the panel so that the heterogeneous areas (including the seams) are at different positions in the sequential line, to effectively smooth out the heterogeneity and reduce the resultant mura to acceptable levels. Dithering.

Structurally, the dithering system may include a rotating wedge or diffusing element disposed within the beam path. This may be very effective in speckle removal in an interference beam, but may be difficult to use in an SLS annealing process because the rotation element contaminates the beam in two dimensions and SLS annealing requires a very narrow line beam. Any dithering / contamination should exist only in the long axis direction of the line beam.

Dithering can be inherently periodic or stochastic. Periodic dithering will follow a periodic profile, such as a sawtooth or sinusoid. Probabilistic dithering will result in a random (or pseudo-random) variance of heterogeneity. The preferred type of dithering will depend on the dithering method and the acceptable level of mura. While probabilistic dithering is expected to be more effective in reducing the spread, periodic dithering can be implemented with less complexity / lower cost while achieving acceptable tolerability.

The magnitude and periodicity (if non-stochastic) of the dithering will depend on the type of heterogeneity, and whether or not any level of mura is acceptable, with or without stitching. Its size and periodicity can range from 10 microns units, potentially in excess of 1 millimeter. One-dimensional dithering can be achieved by some alternative subassemblies shown in Figures 24-28.

Figure 24 shows a dithering system 120 that is operated to oscillate any suitable components after the panel or mask. The panel is oscillated / oscillated in the direction of the line beam during the SLS annealing process. In the case of a device length line, this may be a periodic or stochastic oscillation, as shown in Fig. In the case of a sealed line, it may be necessary to utilize a periodic oscillation, and a continuous pass follows the same periodic path. This will ensure both a constant overlap of the stitched lines and smoothing of the overlapping areas along the scan path. If probabilistic dithering is used with a stitched line, the overlap between successive scans will be highly variable. This may not be acceptable for many types of devices, especially OLED devices.

Figure 25 shows an optical component of a beam delivery system, such as a lens or mirror, oscillating / oscillating in the direction of the line beam during the SLS annealing process, in order to produce the necessary heterogeneity smoothing while maintaining a clear formation of the line beam. The dithering system 120 shown in FIG. If dithering is introduced into the beam in front of the mask plane, the mask can be used to maintain a straight path of the line beam edge on the panel. In this case, periodic or probabilistic dithering may be equally applied. If dithering is introduced after the mask, the resulting line dispersion will be equivalent to oscillating the panel and the same holds for periodic vs. probabilistic dithering as shown in FIG.

Fig. 26 shows another configuration of the dithering system 120 that oscillates the mask. The mask is oscillated / oscillated in the direction of the line beam during the SLS annealing process. This will smooth the seam area between consecutive passes, but will not smooth out the heterogeneity in the line beam. Again, the same holds for periodic versus probabilistic dithering, as for panel oscillation.

While specific embodiments of the invention have been shown and described herein, it will be appreciated by those of ordinary skill in the art that various modifications and rearrangements of parts may be made without departing from the spirit and scope of the basic inventive concept, It is to be clearly understood that the invention is not limited to the specific forms shown and described herein except as indicated by the scope of the appended claims.

Claims (24)

A system for crystallizing amorphous Si (a-Si) panels by partial melting laser annealing (LA) or sequential lateral solidification (SLS)
At least one single transverse mode (SM) quasi-continuous wave (QCW) fiber laser source emitting a pulsed harmonic beam at a pulse repetition rate of at least 80 MHz along a path;
A beam conditioning assembly positioned downstream of the fiber laser source and configured to deform the harmonic beam such that the harmonic beam has desired divergence and spatial dispersion characteristics;
A beam velocity and profile assembly operative to provide a conditioned harmonic beam having a desired intensity profile at a desired scanning rate in an object plane;
A beam imaging assembly for imaging a conditioned harmonic beam in a target plane onto an image plane along at least one beam axis with a desired reduction so that the width of the conditioned harmonic beam is reduced to a narrow line width of at least 1 占 퐉 in the image plane. ; And
To provide the conversion of a-Si into a polysilicon (p-Si) structure having a uniform particle size of 1 mu m or less, at least two times of exposure time for each time of at least 100 ns each And a panel handling assembly operative to provide relative position and velocity between the imaged narrow line width beam and the panel to examine the position of the panel. The method according to claim 1,
Further comprising a plurality of SM QCW fiber laser sources. 3. The method according to claim 1 or 2,
The beam speed and profile system is configured to convert a high-ratio Gaussian harmonic beam to a flat-top harmonic and is selected from a beam fragmentation and recombination system, a beam re-apodization system, a beam combining system, and a beam cropping system. system. 4. The method according to any one of claims 1 to 3,
Wherein the beam fragmentation and recombination system is selected from fly-eye or bi-prism optical arrays. 5. The method according to any one of claims 1 to 4,
Wherein the fly eye is an imaged or non-imaging homogenizer. 4. The method according to any one of claims 1 to 3,
Wherein the beam combining system is configured to superimpose and dot multiple harmonic beams to produce a central, homogeneous, central upper portion of the intensity profile being cropped in the object plane. 4. The method according to any one of claims 1 to 3,
The beam combining system is operated to superimpose a plurality of harmonic beams and one of the superimposed beams is externally so that the resulting harmonic beam is uniform in the longitudinal direction. 4. The method according to any one of claims 1 to 3,
Wherein the beam combining system is comprised of a polarization beam combiner or field lens combiner or a diffracted beam combiner or fly eye. 3. The method according to claim 1 or 2,
The beam re-apodization system is comprised of at least one or a plurality of non-cylindrical optical elements that convert a high-ratio Gaussian harmonic beam into a flat-to-top intensity profile in at least one beam axis. 10. The method according to any one of claims 1 to 9,
Wherein the beam speed and profile system is configured to provide a conditioned harmonic beam having a desired velocity such that the imaged narrow line width beam produces a homogeneous and continuous line of crystallization without stitching. 11. The method of claim 10,
Wherein the scanner is selected from a rotating mirror or an acoustooptic deflector or galvanometer. 12. The method according to any one of claims 1 to 11,
The beam imaging assembly includes a conditioning harmonic beam having a desired intensity profile at a desired scanning velocity in a short beam axis direction on a first mask having a cutting knife for forming a target plane and sharpening the edge of the beam in a major axis direction A focusing lens for focusing, and an objective lens positioned downstream of the first mask and adjacent to the panel. 13. The method of claim 12,
Wherein the beam imaging assembly further comprises a second mask positioned between the first mask and the objective lens and configured to blur the remaining inhomogeneities of the lines of crystallization. 12. The method according to any one of claims 1 to 11,
Wherein the beam imaging assembly is comprised of an anamorphic lens arrangement that provides different hope reduction along orthogonal beam axes of a conditioning harmonic beam having an intensity profile of interest. 12. The method according to any one of claims 1 to 11,
Wherein the beam imaging assembly comprises two spaced masks that are anamorphic and provide different shrinkage along respective orthogonal beam axes and have different object planes. 13. The method according to any one of claims 1 to 12,
Wherein the beam imaging assembly has a proximity mask configured to define a desired length of the beamline on the panel, wherein the proximity mask is spaced from the panel at a distance that limits edge diffraction. 17. The method according to any one of claims 1 to 16,
The panel handling assembly includes a support for supporting the panel to be peened such that the panel can be displaced along orthogonal XY planes relative to the fixed beam imaging assembly. 17. The method according to any one of claims 1 to 16,
Wherein the panel handling assembly includes a support configured to support the panned panel and to be stationary relative to the beam imaging assembly where the panel can be displaced along orthogonal XY planes. 19. The method according to any one of claims 1 to 18,
The panel handling assembly is comprised of a support for supporting the annealed panel such that the panel can be displaced on one of the XY planes and the beam imaging system can be displaced on the other of the XY planes. 20. The method according to claim 18 or 19,
Wherein the SM QCW fiber laser source is mounted or displaceably mounted in a fixed position relative to the displaceable beam imaging system. 21. The method according to any one of claims 1 to 20,
Further comprising an autofocus system, a beam profiler and a mura measurement system. 6. The method according to any one of claims 1 to 5,
Wherein the fly eye homogenizer comprises a delay step glass element to eliminate coherence effects. 23. The method according to any one of claims 1 to 22,
the dithering operation is performed to dither the narrow line width beam onto the panel so that the remaining inhomogeneities of the p-Si structure are at different positions along sequential lines that effectively smooth out the residual inhomogeneity and reduce the mura to a predetermined reference range ≪ / RTI > 24. The method according to any one of claims 1 to 23,
The dithering system is:
Panel, or any suitable component downstream of the target plane, or
Optical components of the beam delivery system, such as a lens or mirror, or
An optical component along the beam path in the direction of the harmonic narrow width line beam conditioned during the SLS annealing process, or
A mask defining a target plane.

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