Patent Publication Number: US-6908835-B2

Title: Method and system for providing a single-scan, continuous motion sequential lateral solidification

Description:
FIELD OF THE INVENTION 
   The present invention relates to a method and system for processing a thin-film semiconductor material, and more particularly to forming large-grained, grain-shaped and grain-boundary-location controlled semiconductor thin films from amorphous or polycrystalline thin films on a substrate using laser irradiation and a continuous motion of the substrate having the semiconductor film being irradiated. 
   BACKGROUND INFORMATION 
   In the field of semiconductor processing, there have been several attempts to use lasers to convert thin amorphous silicon films into polycrystalline films. For example, in James Im et al., “Crystalline Si Films for Integrated Active-Matrix Liquid-Crystal Displays,” 11 MRS Bulletin 39 (1996), an overview of conventional excimer laser annealing technology is described. In such conventional system, an excimer laser beam is shaped into a beam having an elongated cross-section which is typically up to 30 cm long and 500 micrometers or greater in width. The shaped beam is stepped over a sample of amorphous silicon (i.e., by translating the sample) to facilitate melting thereof and to effectuate the formation of grain-shape and grain boundary-controlled polycrystalline silicon upon the re-solidification of the sample. 
   The use of conventional laser annealing technology to generate polycrystalline silicon is problematic for several reasons. First, the polycrystalline silicon generated in the process is typically small grained, of a random micro structure (i.e., poor control of grain shapes and grain boundary locations), and having a nonuniform grain size, therefore resulting in poor and nonuniform devices and accordingly, low manufacturing yield. Second, in order to obtain acceptable quality grain-shape and grain-boundary-location controlled polycrystalline thin films, the manufacturing throughput for producing such thin films must be kept low. Also, the process generally requires a controlled atmosphere and preheating of the amorphous silicon sample, which leads to a reduction in throughput rates. Accordingly, there exists a need in the field for a method and system for growing amorphous or polycrystalline thin semiconductor films to produce higher quality thin polycrystalline or single crystalline semiconductor silicon films at greater throughput rates. There likewise exists a need for manufacturing techniques which generate larger and more uniformly microstructured polycrystalline silicon thin films to be used in the fabrication of higher quality devices, such as thin film transistor arrays for liquid crystal panel displays. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide techniques for producing large-grained and grain-shape and grain-boundary, location controlled polycrystalline thin film semiconductors using a sequential lateral solidification (“SLS”) process, and to generate such silicon thin films in an accelerated manner. Another object of the present invention is to effectuate such accelerated sequential lateral solidification of the polycrystalline thin film semiconductors provided on a simple and continuous motion translation of the semiconductor film, without the necessity of “microtranslating” the thin film, and re-irradiating the previously irradiated region in the direction which is the same as the direction of the initial irradiation of the thin film while the sample is being continuously translated. 
   At least some of these objects are accomplished with a method and system for processing a semiconductor thin film sample on a substrate. The substrate has a surface portion that does not seed crystal growth in the silicon thin film. The film sample has a first edge and a second edge. An irradiation beam generator is controlled to emit successive irradiation beam pulses at a predetermined repetition rate. Each of the irradiation beam pulses is masked to define a first plurality of beamlets and a second plurality of beamlets, the first and second plurality of beamlets of each of the irradiation pulses being provided for impinging the film sample and having an intensity which is sufficient to melt irradiated portions of the film sample throughout their entire thickness. The film sample is continuously scanned, at a constant predetermined speed, so that a successive impingement of the first and second beamlets of the irradiation beam pulses occurs in a scanning direction on the film sample between the first edge and the second edge. During the continuous scanning of the film sample, a plurality of first areas of the film sample are successively irradiated using the first beamlets of the irradiation beam pulses so that the first areas are melted throughout their thickness and leaving unirradiated regions between respective adjacent ones of the first areas. Also during the continuous scanning, each one of the first areas irradiated using the first beamlets of each of the irradiation beam pulses is allowed to re-solidify and crystalize. During resolidification and crystallization of the first areas, a plurality of second areas of the film sample are successively irradiated using the second beamlets of the irradiation beam pulses so that the second areas are melted throughout their thickness. Each of the second areas partially overlaps a respective pair of the re-solidified and crystalized first areas and the respective unirradiated region therebetween. 
   In another embodiment of the present invention, during the successive irradiation of the second areas by the second beamlets, third areas of the film sample are successively irradiated by the first beamlets to completely melt the third areas throughout their thickness, each of the third areas partially overlapping a respective one of the re-solidified and crystalized first areas and leaving further unirradiated regions between respective adjacent ones of the third areas. One of the first areas and one of the third areas may lie on a first line which is parallel to the scanning direction, and one of the second areas may lie of a second line which is parallel to the scanning direction. The first line preferably extends at an offset from the second line. Upon the successive irradiation of the third areas by the first beamlets, each one of the second areas irradiated by the first beamlets of each of the irradiation beam pulses can be allowed to re-solidify and crystalize. 
   According to another embodiment of the present invention, when the film sample is continuously scanned, each one of the third areas irradiated by the first beamlets of each of the irradiation beam pulses is allowed to re-solidify and crystalize. 
   After the irradiation of the second and third areas, a plurality of fourth areas of the film sample are successively irradiated by the second beamlets of the irradiation beam pulses so that the fourth areas are melted throughout their thickness, wherein each one of the fourth areas partially overlaps a respective pair of the re-solidified and crystalized third areas and the respective further unirradiated region therebetween. 
   In yet another embodiment of the present invention, the first edge is located on a side of the film sample which is opposite from a side of the film sample on which the second edge is located. In addition, the first and second impingements along the film sample is continued until the first impingement by the first set of patterned beamlets of the film sample and the second impingement by the second set of patterned beamlets of the film sample passes the second edge of the film sample. Thereafter, the film sample can be positioned so that the first and second sets of patterned beamlets impinge on at a first location outside of boundaries of the film sample with respect to the film sample, and then the film sample may be translated so that impingement of the first and second sets of patterned beamlets moves from the first location to a second location, the second location being outside of the boundaries of the film sample. Finally, the film sample can be maintained so that the patterned beamlets impinge on the second location until any vibration of the film sample is damped out. With this embodiment, a completed portion of the film sample having a predetermined width has preferably been irradiated and re-solidified, the film sample having a controlled crystalline grain growth in the entire completed portion. 
   In still another embodiment, the particular direction extends along a first path, the film sample is translated along a second path which is perpendicular to the first path. The successive impingement by the first and second beamlets of the irradiation beam pulses the film sample may pass the second edge of the film sample. After, the successive irradiation of the first and second areas, the film sample is positioned so that the first and second beamlets of the irradiation beam pulses impinge on at a first location outside of boundaries of the film sample with respect to the film sample. Thereafter, the film sample can be positioned so that the successive impingement of the first and second beamlets with respect to the film sample moves from the first location to a second location, the second location being outside of the boundaries of the film sample. A completed portion of the film sample having a predetermined width which has been irradiated, melted throughout its entire thickness and re-solidified can be defined, with the film sample having a controlled crystalline grain growth in the entire completed portion. The particular direction may extend along a first path, and the film sample may be translated along a second path, the first axis being perpendicular to the first path. The second location can be provided at the distance from the first location approximately equal to the predetermined width. 
   According to another embodiment of the present invention, the film sample can be continuously scanned, at the constant predetermined speed, so that the successive impingement of the first and second beamlets of the irradiation beam pulses occurs in a further direction on the film sample between the second edge and the first edge, the further direction being opposite to the scanning direction. At that time, a plurality of fifth areas of the film sample can be successively irradiated with the second beamlets of the irradiation beam pulses so that the fifth areas are melted throughout their thickness and leaving additional unirradiated regions between respective adjacent ones of the fifth areas. Also, each one of the fifth areas irradiated by the second beamlets of each of the irradiation beam pulses can be allowed to re-solidify and crystalize. Furthermore, a plurality of sixth areas of the film sample can be successively irradiated by the first beamlets of the irradiation beam pulses so that the sixth areas are melted throughout their thickness, with each one of the sixth areas partially overlapping a respective pair of the re-solidified and crystalized fifth areas and the respective unirradiated region therebetween. 
   In still another embodiment, portions of the irradiation beam pulses can be masked to emit successive partial intensity irradiation pulse which have a reduced intensity so that when the successive partial intensity irradiation pulses irradiate a particular region of the film sample, the particular region is melted for less than the entire thickness of the film sample. Then, each of the re-solidified and crystalized second areas can be successively irradiated by the respective one of the successive partial intensity irradiation pulses. 
   In a further embodiment of the present invention, a method and system for processing a semiconductor thin film sample on a substrate is provided. The substrate has a surface portion that does not seed crystal growth in the semiconductor thin film. The film sample has a first edge and a second edge. An irradiation beam generator is controlled to emit successive irradiation beam pulses at a predetermined repetition rate. Each of the irradiation beam pulses is masked to define a first plurality of beamlets and a second plurality of beamlets, the first and second plurality of beamlets of each of the irradiation pulses being provided for impinging the film sample and having an intensity which is sufficient to melt irradiated portions of the film sample throughout their entire thickness. The film sample is continuously scanned, at a constant predetermined speed, so that a successive impingement of the first and second beamlets of the irradiation beam pulses occurs in a scanning direction on the film sample between the first edge and the second edge. During the continuous scanning of the film sample, a plurality of first areas of the film sample are successively irradiated using the first beamlets of the irradiation beam pulses so that the first areas are melted throughout their thickness and leaving unirradiated regions adjacent to the first areas. Each of the first areas has a first border with a first width, the border extending along a first line which is perpendicular to the scanning direction. Also during the continuous scanning, each one of the first areas irradiated using the first beamlets of each of the irradiation beam pulses is allowed to re-solidify and crystalize. Following the resolidification and crystallization of the first areas, a plurality of second areas of the film sample are successively irradiated using the second beamlets of the irradiation beam pulses so that the second areas are melted throughout their thickness. A first region of each one of the second areas completely overlaps at least one of the re-solidified and crystalized first areas, and a second region of the respective one of the second areas overlaps the respective unirradiated region provided adjacent to the re-solidified and crystalized first area. The first region has a second border with a second width which is greater than half of the first width, the second border extending along a second line which is parallel to and offset from the first line. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the present invention will now be described in further detail with reference to the accompanying drawings in which: 
       FIG. 1  shows a diagram of an exemplary embodiment of a system for performing a single-scan continuous motion sequential lateral solidification (“SLS”) according to the present invention which does not require a microtranslation of a sample for an effective large grain growth in a silicon thin film; 
       FIG. 2  shows an enlarged view of an exemplary embodiment of the sample conceptually subdivided and having the silicon thin film thereon; 
       FIG. 3  shows an enlarged illustration of an intensity pattern of an irradiation beam pulse as defined by a first exemplary embodiment of a mask utilized by the system and method of the present invention which facilitates the single-scan, continuous motion SLS as it impinges the silicon thin film on a substrate; 
       FIG. 4  shows an exemplary irradiation path of beam pulses impinging the sample, as the sample is translated by the system of  FIG. 1 , using a first exemplary embodiment of the method according to the present invention which provides the single-scan, continuous motion SLS; 
       FIGS. 5A-5G  show the radiation beam pulse intensity pattern and portions of grain structures on an exemplary first conceptual column of the sample having the silicon thin film thereon at various sequential stages of the SLS processing according to the first exemplary embodiment of the method of the present invention illustrated in  FIG. 4 , in which the intensity pattern of the irradiation beam pulse of  FIG. 3  is used to irradiate a first conceptual column of the sample; 
       FIGS. 6A and 6B  show the radiation beam pulse intensity pattern and portions of the grain structures on an exemplary second conceptual column of the sample having the silicon thin film thereon at two sequential stages of SLS processing according to the first exemplary embodiment of the method of the present invention illustrated in  FIG. 4 , which is performed along a second conceptual column of the sample, after the silicon thin film of the entire first conceptual column of the sample illustrated in  FIGS. 5A-5G  is completely melted, re-solidified and crystalized; 
       FIG. 7  shows an illustrative diagram of the crystallized silicon film of the sample after the silicon thin film in all conceptual columns of the sample is completely melted, re-solidified and crystalized; 
       FIG. 8  shows an enlarged illustration of a second exemplary embodiment of an intensity pattern of the irradiation beam pulse as defined by a further mask utilized by the system and method of the present invention as it impinges the silicon thin film on the substrate, which promotes a growth of larger grains in the silicon thin film; 
       FIG. 9  shows the radiation beam pulse intensity pattern and the grain structure of a portion of an exemplary first conceptual column of the sample having the silicon thin film thereon at an exemplary stage of the SLS processing according to a second exemplary embodiment of the method of the present invention which utilizes the mask illustrated in  FIG. 8  for growing longer grains in the silicon thin film; 
       FIG. 10  shows an illustrative diagram of a further progression of the SLS processing of  FIG. 9  for the silicon thin film of the sample after the beam pulses complete the irradiation of a particular portion of the first conceptual column of the sample, which then crystallizes; 
       FIG. 11  shows an enlarged illustration of a third exemplary embodiment of an intensity pattern of the irradiation beam pulse as defined by another mask utilized by the system and method of the present invention as it impinges the silicon thin film of the sample, which includes a single lower-energy portion provided adjacent to one section of slit-shaped beamlets of the irradiation beam pulse; 
       FIG. 12  shows an enlarged illustration a fourth exemplary embodiment of an intensity pattern of the irradiation beam pulse as defined by yet another mask utilized by the system and method of the present invention as it impinges the silicon thin film of the sample, which includes two lower-energy portions, each provided opposite to one another and adjacent to a respective different section of slit-shaped beamlets of the irradiation beam pulse; 
       FIGS. 13A-13D  show the radiation beam pulse intensity pattern and the grain structure of a portion of an exemplary conceptual first column of the silicon thin film provided on the sample at various sequential stages of SLS processing according to a third exemplary embodiment of the method of the present invention, which uses the technique of the first embodiment of the method illustrated in  FIGS. 5A-5G , after the sample is rotated 90° in a clock-wise direction; 
       FIG. 14  shows an illustrative diagram of the crystallized silicon film of the sample after the silicon thin film in all conceptual columns of the rotated sample have been completely melted, re-solidified and crystalized using the technique illustrated in  FIGS. 13A-13D ; and 
       FIG. 15  shows a flow diagram illustrating the steps implemented by the system of FIG.  1  and the method illustrated in  FIGS. 5A-5G  and  6 A- 6 B according to one exemplary embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Certain systems and methods for providing a continuous motion SLS are described in U.S. patent application Ser. No. 09/526,585 (the “&#39;585 application”), the entire disclosure of which is incorporated herein by reference. The &#39;585 application explicitly describes and illustrates the details of these systems and methods, and their utilization of microtranslations of a sample, which has an amorphous silicon thin film provided thereon being irradiated by irradiation beam pulses to promote the sequential lateral solidification on the thin film. Similar to the system described in the &#39;585 application, an exemplary embodiment of a system for carrying out the continuous motion SLS processing of amorphous silicon thin films according to the present invention is illustrated in FIG.  1 . The exemplary system includes a Lambda Physik model LPX-315I XeCl pulsed excimer laser  110  emitting an irradiation beam (e.g., a laser beam), a controllable beam energy density modulator  120  for modifying the energy density of the laser beam, a MicroLas two plate variable attenuator  130 , beam steering mirrors  140 ,  143 ,  147 ,  160  and  162 , beam expanding and collimating lenses  141  and  142 , a beam homogenizer  144 , a condenser lens  145 , a field lens  148 , a projection mask  150  which may be mounted in a translating stage (not shown), a 4×-6× eye piece  161 , a controllable shutter  152 , a multi-element objective lens  163  for focusing an incident radiation beam pulse  164  onto a sample  40  having a silicon thin film  52  to be SLS processed mounted on a sample translation stage  180 , a granite block optical bench  190  supported on a vibration isolation and self-leveling system  191 ,  192 ,  193  and  194 , and a computer  106  (e.g., a general purpose computer executing a program or a special-purpose computer) coupled to control the pulsed excimer laser  110 , the beam energy density modulator  120 , the variable attenuator  130 , the shutter  152  and the sample translation stage  180 . 
   The sample translation stage  180  is controlled by the computer  106  to effectuate translations of the sample  40  in the planar X-Y directions and the Z direction. In this manner, the computer  106  controls the relative position of the sample  40  with respect to the irradiation beam pulse  164 . The repetition and the energy density of the irradiation beam pulse  164  are also controlled by the computer  106 . It should be understood by those skilled in the art that instead of the pulsed excimer laser  110 , the irradiation beam pulse can be generated by another known source of short energy pulses suitable for melting a semiconductor (or silicon) thin film  52  in the manner described herein below. Such known source can be a pulsed solid state laser, a chopped continuous wave laser, a pulsed electron beam and a pulsed ion beam, etc. with appropriate modifications to the radiation beam path from the source  110  to the sample  40 . While the computer  106 , in the exemplary embodiment of the system shown in  FIG. 1 , controls translations of the sample  40  for carrying out the single-scan, continuous motion SLS processing of the silicon thin film  52  according to the present invention, the computer  106  may also be adapted to control the translations of the mask  150  and/or the excimer laser  110  mounted in an appropriate mask/laser beam translation stage (not shown for the simplicity of the depiction) to shift the intensity pattern of the irradiation beam pulses  164 , with respect to the silicon thin film  52 , along a controlled beam path. Another possible way to shift the intensity pattern of the irradiation beam pulse is to have the computer  106  control a beam steering mirror. The exemplary system of  FIG. 1  may be used to carry out the single-scan, continuous motion SLS processing of the silicon thin film  52  on the sample  40  in the manner described below in further detail. 
   As described in further detail in the &#39;585 application, an amorphous silicon thin film sample is processed into a single or polycrystalline silicon thin film by generating a plurality of excimer laser pulses of a predetermined fluence, controllably modulating the fluence of the excimer laser pulses, homogenizing the intensity profile of the laser pulse plane, masking each homogenized laser pulses to define beamlets, irradiating the amorphous silicon thin film sample with the beamlets to effect melting of portions thereof that were irradiated by the beamlets, and controllably and continuously translating the sample with respect to the patterned beamlets. The output of the beamlets, as provided in the &#39;585 application, is controllably modulated to thereby process the amorphous silicon thin film provided on the sample into a single or grain-shape, grain-boundary-location controlled polycrystalline silicon thin film by the continuous motion sequential translation of the sample relative to the beamlets, and the irradiation of the sample by the beamlets of masked irradiation pulses of varying fluence at corresponding sequential locations thereon. One of the advantageous improvements of system and method according to the present invention is that there is a significant saving of processing time to irradiate and promote the SLS on the silicon thin film of the sample by completing the irradiation of a section of the sample  40  without the requirement of any microtranslation of the sample to be performed (i.e., the microtranslations as described in the &#39;585 application). 
     FIG. 2  shows an enlarged view of an exemplary embodiment of the sample  40  having the amorphous silicon thin film  52  thereon. This exemplary sample  40 , as shown in  FIG. 2 , is sized 40 cm in the Y-direction by 30 cm in the X-direction. The sample  40  is conceptually subdivided into a number of columns (e.g., a first column  210 , a second column  220 , etc.). The location/size of each column is stored in a storage device of the computer  106 , and utilized by the computer  106  for later controlling the translation of the sample  40 . Each of the columns  210 ,  220 , etc. is dimensioned, e.g., 2 cm in the X-direction by 40 cm in the Y-direction. Thus, if the sample  40  is sized 30 cm in the X-direction, the sample  40  may be conceptually subdivided into fifteen (15) columns. Within the constraints of the system discussed below, the sample  40  may be subdivided into columns having different dimensions (e.g., 1 cm by 40 cm columns, 3 cm by 40 cm columns, 4 cm by 40 cm columns, etc.). When the sample  40  is conceptually subdivided into columns, at least a small portion of each column extending for the entire length of the column should be overlapped by the neighboring column(s), i.e., an overlapped portion  230 , so as to avoid a possibility of having any unirradiated areas of the silicon thin film  52 . The overlapped portions  230  are preferably provided between all neighboring columns. For example, the overlapped area may have a width of 1 μm. It should be understood that other widths of the overlapped portions are possible, such as 2 μm, and are within the scope of the present invention. 
     FIG. 3  shows an enlarged illustration of a first exemplary embodiment of an intensity pattern  235  of the masked irradiation beam pulse  164  which is defined by the mask  150  as it impinges the silicon thin film  52  provided on the sample  40 . The intensity pattern  235  is produced by placing the mask  150 , which has a particular pattern of the transparent and opaque regions, in the path of the homogenized irradiation beam  149 , and the resultant beamlets exiting the mask  150  are focused by the objective lens  163  to produce the masked irradiation beam pulse  164  having the desired intensity pattern  235 . Using such intensity pattern  235 , the system and method of the present invention can effectuate the single-scan, continuous motion SLS of the silicon thin film  52 . The first exemplary intensity profile  235  shown in this drawing includes two beamlet sections  250 ,  260 , with the slit-shaped beamlets in each section being separated from one another in a predetermined manner. The location of the slit-shaped beamlets  255  of the first section  250  are provided at an offset in the X-direction with respect to the location of the slit-shaped beamlets  265  of the second section  260 . A detailed discussion of the exemplary intensity pattern  235  shown in  FIG. 3  is provided below. 
   As described above, the intensity pattern  235  includes two sections, i.e., a first beamlet section  250  and a second beamlet section  260 . The first beamlet section  250  has first slit-shaped beamlets  255 , each having a width of approximately 3 μm in the X-direction and a length of approximately ½ mm in the Y-direction. The first slit-shaped beamlets  255  are equidistantly spaced from one another by first shadow regions  257  (i.e., the first slit-shaped beamlets  255  are spaced apart from one another by these first shadow regions  257 ). The first shadow regions  257  may have a width of, e.g., 1½ μm. 
   As shown in  FIG. 3 , the second beamlet section  260  is located substantially adjacent to the first beamlet section  250  in the Y-direction, and has second slit-shaped beamlets  265 . The second beamlet section  260  includes second shadow regions  267  separating the second slit-shaped beamlets  265  from one another. The second slit-shaped beamlets  265  and the second shadow regions  267  are separated from the first slit-shaped beamlets  255  and the first shadow regions  257  by an intervening shadow region  240 . The dimensions of the second slit-shaped beamlets  265  and the second shadow regions  267  are substantially similar to those of the first slit-shaped beamlets  255  and the first shadow regions  257 , respectively. It is preferable for an edge  258  of each one of the first slit-shaped beamlets  255 , which extends in the Y-direction, to coincide with a line M which extends into the area of a respective one second slit-shaped beamlet  265 , and for the other edge  259  of each first slit-shaped beamlet  255  to coincide with a line N which extends into the area of the second slit-shaped beamlets  265  adjacent to the one of the second slit-shaped beamlets having the line M extending therethrough. The first beamlet section  250  is separated from the second beamlet section  260  by an intervening shadow region  240  having a width of 5 μm. It should be noted that the masked irradiation beam pulse  164  does not project any beam energy into the shadow regions  257 ,  267 ,  240 , while providing the full laser pulse intensity of the beamlets onto the silicon thin film  52 . 
   Therefore, the dimension of the intensity pattern  235  in the Y-direction should be approximately 1.005 mm after adding the length of the first slit-shaped beamlets  255  (½ mm) and those of the second slit-shaped beamlets  265  (½ mm), plus 5 μm to account for the intervening shadow region  240 . The dimension of the intensity pattern  235  in the X-direction should be equal to the width of the conceptual columns  210 ,  220 . Therefore, the approximate dimension of the exemplary intensity pattern  235  shown in  FIG. 3  is 2 cm in the X-direction by approximately 1.005 mm in the Y-direction. In addition, the cross-section of the homogenized irradiation beam  149  should be at least large enough to cover the portion of the mask  150  that defines the intensity pattern  235 . The array of beamlets  151  exiting the mask  150  and then focused by the objective lens  163  results in the masked irradiation beam pulse  164  having dimensions in the X-direction that substantially matches the width of each of the conceptual columns  210 ,  220  of the sample  40 . It is preferable for the width the cross-sections of the masked irradiation beam pulse  164  (and thus of the intensity pattern  235 ) in the X-direction to be slightly greater than the width of each of the conceptual columns  210 ,  220 . The advantages of such dimensions will be understood from the further description of the first embodiment of the method according to the present invention as discussed in greater detail below. 
   It should be understood that the width of the first and second slit-shaped beamlets  255 ,  265  may depend on a number of factors, e.g., the energy density of the incident laser pulse, the duration of the incident irradiation beam pulse, the thickness of the silicon thin film  52  provided on the sample  40 , the temperature and thermal conductivity of the substrate, etc. While it is desirable from the standpoint of processing efficiency to utilize the slit-shaped beamlets  255 ,  265  which have a larger width in the X-direction so as to cover a greater width of the sample  40 , it is important to select the width of the first and second slit-shaped beamlets  255 ,  265  such that when portions of the silicon thin film  52  provided on the sample  40  are irradiated thereby and are completely melted throughout their thickness, no nucleation occurs within such melted portions when they re-solidify and crystalize. In particular, if the width of the slit-shaped beamlets  255 ,  265  is too large, certain areas within the fully-melted portions may re-solidify before the controlled lateral grain growth reaches these areas. If this occurs, the control of the grain growth in the irradiated areas will be compromised. 
   Other dimension and shapes of the first slit-shaped beamlets  255 , the first shadow regions  257 , the second slit-shaped beamlets  265 , the second shadow regions  267  and/or the shadow region  240  are contemplated, and are within the scope of the present invention. For example, if the extension or length of each of the first and second slit-shaped beamlets  255 ,  265  is approximately 1 mm (i.e., instead of ½ mm), the dimension of the intensity pattern  235  of the masked irradiation beam pulse  164  in the Y-direction would be 2 mm. 
   One of the important aspects of the intensity pattern  235  according to the present invention is that if the sample  40  is translated such that portions of the silicon thin film areas previously irradiated by the first beamlet section  250  (as well as re-solidified and crystalized) are irradiated by the second beamlet section  260 , each of the slit-shaped second beamlets partially overlap a respective pair of regions previously irradiated by the first slit-shaped beamlets  255  of the first beamlet section  250 , as well as overlapping the unirradiated region (i.e., the region overlapped by a respective shadow region  257 ) therebetween. This is because when the sample  40  is translated in the Y-direction by the sample translation stage  180 , the second slit-shaped beamlets  265  of the masked irradiation beam pulse  164  should completely melt a portion of the silicon thin  52  film which was previously melted (by the first slit-shaped beamlets  255  of the masked irradiation beam pulse  164 ), cooled, re-solidified and crystallized. Such preferable technique according to the present invention promotes the lateral, controlled grain growth in the cooling regions of the silicon thin film  52  to extend such grain growth from the area that was completely melted by the first slit-shaped beamlets  255 , cooled and re-solidified (and not later re-melted) into the area that was previously solidified and re-melted, and to further extend lateral crystal into the newly melted area (that is adjacent to the originally-melted area). The details of this technique and method according to the preferred embodiment of the present invention is described in further detail below. 
   For the exemplary sample  40  shown in FIG.  2  and described above, and for the purposes of the foregoing, the intensity pattern  235  of the masked irradiation beam pulse  164  may be defined as 2 cm in the X-direction by ½ cm in the Y-direction (e.g., a rectangular shape). However, as described above, the intensity pattern  235  of the masked irradiation beam pulse  164  is not limited to any particular shape or size. Indeed, other shapes and/or sizes of the intensity pattern  235  may be used, as would be apparent to those having ordinary skill in the art based on the teachings provided herein (e.g., square shape, circle, etc.). It should be understood that if a different the intensity pattern of the masked irradiation beam pulse  164  is desired, the mask  150 , and possibly of the homogenized irradiation beam  149  would have to be modified to define the intensity pattern  235  after focusing by the objective lens  163 . 
   The cross-section of the masked irradiated beam pulse  164  (i.e., the beam pulse area (B A )) can be determined as follows: 
               B   A     ≈         E   PULSE     ×     K   OPTICS         E   ⁢           ⁢     D   PROCESS                 (   1   )             
 
where E PULSE  is the energy per pulse of the laser or pulsed irradiation beam, K OPTICS  is the fraction of the irradiation beam energy passing through the optics of the system, and ED PROCESS  is the energy density of the process (e.g., 500 mJ/cm 2  for 500 Å silicon thin film and 30 nseconds pulse duration). It is preferably to determine ED PROCESS  experimentally.
 
   Referring now to  FIGS. 4 ,  5 A- 5 G and  6 A- 6 B to describe the details of the first exemplary embodiment of the method according to the present invention,  FIG. 4  shows an exemplary irradiation path of beam pulses impinging portions of the silicon thin film  52  provided on the sample  40  as the sample  40  is translated under the control of the computer  106  by the sample translation stage  180  of FIG.  1 . In this drawing, a first exemplary embodiment of a method which effectuates the single-scan, continuous motion SLS according to the present invention, is utilized.  FIGS. 5A-5G  show the intensity pattern of the radiation beam pulse  164  and the grain structure on an exemplary first conceptual column  210  of a silicon thin film on the sample  40  at various sequential stages of continuous motion SLS processing according to the first exemplary embodiment of the method of the present invention, which is discussed below with reference to FIG.  4 . In this part of the method, the masked radiation beam pulses  164  have an intensity pattern defined by the mask  150  to provide the intensity pattern  235  which is illustrated in FIG.  3 .  FIGS. 6A-6B  show the masked radiation beam pulse intensity pattern and portions of the grain structures in an exemplary second conceptual column  220  of the sample  40  having the silicon thin film  52  thereon at two sequential stages of SLS processing according to the first exemplary embodiment of the method of the present invention illustrated in FIG.  4 . This part of the method is performed after the silicon thin film  52  of the entire conceptual first column  210  of the sample  40  illustrated in  FIGS. 5A-5G  is completely melted, cooled, re-solidified and crystalized. 
   Turning first to  FIG. 4 , the sample  40  is placed on the sample translation stage  180 , which is controlled by the computer  106 . The sample  40  is placed such that the fixed position masked irradiation beam pulse  164  (having the intensity pattern  235  defined by the mask  150 ) impinges on a location  300  away from the sample  40 . Thereafter, the sample  40  is translated in the Y-direction, and gains momentum to reach a predetermined velocity before the masked irradiation beam pulse  164  reaches and impinges an edge  45  of the sample  40  at a location  310 . This is shown in  FIG. 4  as a path  305  which illustrates the path of the masked irradiation beam pulse  164  as the sample  40  is translated in the Y-direction. By controlling the motion of the sample  40  in the X and Y directions, the computer  106  controls the relative position of the sample  40  with respect to the masked irradiation beam pulse  164  which irradiates the silicon thin film  52  provided on the sample  40 . The pulse duration, the pulse repetition rate and the energy of each pulse of the masked irradiation beam pulse  164  are also controlled by the computer  106 . 
   In the first embodiment of the present invention as illustrated in  FIG. 4 , the sample  40  is translated with respect to the stationary irradiation beam pulse  164  in order to sequentially irradiated successive portions of the silicon thin film  52  along predefined paths of irradiation to obtain a lateral growth of large grains having controlled grain size and shape, and controlled grain boundary location and orientation in the silicon thin film  52 . In particular, as the sample  40  is translated in the Y-direction, the stationary irradiation beam pulse  164  impinges and melts successive portions of the entire first column  210  along a path  315 , starting from the location  310  until the radiation beam pulse  164  reaches a bottom edge  47  (opposite and parallel to the edge  45 ) at a location  320 . The masked irradiated beam pulses  164  are only limited to the intensity pattern  235  defined by the mask  150  so long as each beamlet of the intensity pattern  235  of each masked irradiation beam pulse  164  has sufficient energy to melt a region of the silicon thin film  52  which it irradiates throughout its entire thickness, and each melted region of the silicon thin film  52  is sufficiently dimensioned to allow the lateral growth of grains in the melted region without nucleation inside the melted regions. 
   To reiterate, the paths of the irradiation of the silicon thin film  52  are shown in  FIG. 4  in the frame of reference of the translating sample  40  so that the stationary irradiation beam pulse  164  (shown in  FIG. 1 ) is depicted as traversing the stationary sample  40 . 
   As shown in  FIG. 4 , the computer  106  causes the radiation beam pulse  164  to be emitted and the sample  40  to be positioned such that the masked irradiated beam pulse  164  impinges a first location  300  in the frame of reference of the sample  40 . The sample  40  is then accelerated in the +Y direction under the control of the computer  106  to reach a predetermined velocity with respect to the stationary irradiation beam pulse  164 , which traces a first path  305  not on the sample  40 . It is noted again that the path  305  is not the result of movement of the masked irradiated beam pulse  164 , which is stationary, but represents the movement of the sample  40  relative to the stationary irradiation beam pulse  164 . 
   When the upper edge  45  of the sample  40  reaches the position of impingement by the radiation beam pulse  164  at the location  310 , the sample  40  is translating at the predetermined velocity with respect to the stationary irradiation beam pulse  164 . The predetermined velocity V can be defined according to the following equation: 
             V   =     f   ×       w   B     2               (   2   )             
 
where f is the frequency (pulse repetition rate) of the stationary irradiation beam pulse  164  and W B  is the dimension of the masked irradiation beam pulse  164  in the Y-direction. As discussed above, the dimension of the masked irradiated beam pulse  164  in the Y-direction may be 2 cm. The frequency f of the stationary irradiation beam pulse  164  may have a repetition pulse rate between 100 hertz and 500 hertz (preferably 250 hertz). In this embodiment of the present invention, the predetermined velocity is, for example, 250 cm/sec. It is also possible to utilize other frequency ranges depending on the configuration and the type of the excimer laser  110  being used. Thereafter, the sample  40  is continuously translated in the +Y direction at the predetermined velocity while the masked irradiated beam pulses  164  irradiates successive portions of the silicon thin film  52  provided on the sample  40  at a predetermined pulsed repetition rate along a second irradiation path  315 , which traverses the length of the sample  40  in the −Y direction.
 
     FIGS. 5A-5G  illustrate the sequential steps of the irradiation (i.e., by the radiation beam pulse  164 ) and the re-solidification of the first column  210  of the silicon thin film  52  provided on the sample  40  as the sample  40  is translated in the +Y direction so that the successive portion of the silicon thin film  52  in the first column  210  of the sample  40  are irradiated along the second irradiation path  315 . 
   In particular,  FIG. 5A  shows the irradiation and complete melting of first areas  410  of the silicon thin film  52  in the first conceptual column  210  adjacent to the top edge  45  of the sample  40  where the sample  40  is overlapped only by the first beamlet section  250  of the intensity pattern  235  of the stationary radiation beam pulse  164 , and the first slit-shaped beamlets  255  irradiates and completely melts the silicon thin film  52  in areas  410  of the sample. Regions  415  of the silicon thin film  52  on the sample  40  are not irradiated and melted as a result of being overlapped by the first shadow regions  257  of the intensity pattern  235  of the masked irradiated beam pulse  164 . 
   As the sample  40  is translated past the location  310  (illustrated in FIG.  4 ), the masked irradiated beam pulse  164  provides emit the first slit-shaped beamlets  255  of the intensity profile  235  (or a first masked radiation beam pulse) and irradiates each of the first areas  410  of the silicon thin film  52  on the first conceptual column  21 C. In this manner, the silicon thin film portions provided in the first areas  410  are melted throughout the entire thickness thereof. It should be noted that each of the regions  415  of the first column  210  of the sample  40 , overlapped by a respective one of the first shadow regions  257  of the intensity profile  235  remains unmelted. 
   Turning now to  FIG. 5B , before the irradiation by a second irradiation beam pulse, in accordance with the predetermined pulse repetition rate, each of the areas  410  of the silicon thin film  52  in the first conceptual column  210  of the sample  40  that were melted by the first radiation beam pulse cools, re-solidifies and crystalizes to form two columns of grains  420 ,  425  grown towards one another from the respective adjoining unmelted regions  415 . 
   During re-solidification and crystallization of the melted first areas  410 , the unmelted regions  415  bordering the melted first areas  410  seed the lateral growth of grains in respective adjoining melted first areas  410 . The two columns  420 ,  425  abut one another along a respective one of a plurality of grain abutment boundaries  430  after the abutting grains have grown by a characteristic growth distance of approximately 1.5 μm. Both columns of grains  420 ,  425  in each one of the re-solidification first areas  410  have a respective central portion in which grain boundaries form large angles (e.g., approximately 90°) with respect to the irradiation path  315 . 
   While the cooling, re-solidification and crystallization of the melted areas  410  is taking place, the sample  40  is being continuously translated with respect to the stationary irradiation beam pulse  164  along the irradiation path  315  in the Y-direction. This is because when another area of the silicon thin film  52  on the first column  210  is irradiated by the second radiation beam pulse, the second beamlets  265  of the intensity pattern  235  of the stationary irradiation beam pulse  164  impinges the respective portion of the silicon thin film  52  so as to only partially overlap the respective adjacent pairs of the re-solidified and crystalized areas  410  and the unirradiated regions therebetween. For example, the timing for the emission of the second radiation beam pulse is controlled such that the distance of the translation of the sample  40  is less than the length of the first slit-shaped beamlets  255  (e.g., ½ mm). 
   Turning to  FIG. 5C , the silicon thin film  52  in the first conceptual column  210  of the sample  40  is irradiated using both the first and second beamlet sections  250 ,  260  of the intensity profile  235 . When the sample  40  reaches the position on the first column  210  at which the first slit-shaped beamlets  255  of the intensity profile  235  would overlap certain portions of the re-solidified areas  410 , the computer  106  controls the excimer laser  110  to generate another irradiation beam pulse through the mask  150  (i.e., the second radiation beam pulse) to irradiate particular areas of portions of the silicon thin film  52  in the first conceptual column  210 . The computer  106  times the pulses and controls the translation of the sample  40  so that the second radiation beam pulse irradiates the appropriate areas of the silicon thin film  52  as discussed below. 
   As shown in  FIG. 5C , the second radiation laser pulse is generated so that the first slit-shaped beamlets  255  irradiate and completely melt second areas  435  of the silicon thin film  52  in the first conceptual column  210 , and the second slit-shaped beamlets  265  completely melt third areas  445  of the silicon thin film  52  in the first conceptual column  210 . The second areas  435  preferably extend along the same scanning path in the first column  210  as the first areas  410  that are shown in FIG.  5 B. However, the second areas  435  are provided at an offset, the distance of which is slightly less than then length of the first areas  410  (i.e., ½ mm) in the negative Y-direction. As shown in  FIG. 5C , overlapped areas  440  are provided between the first areas  410  and the second areas  435  which are small sections of the first areas  410  that were re-solidified, but again completely melted by the first slit-shaped beamlets  255  of the intensity profile  255 . The computer  106  controls the timing of the pulses and the translation of the sample  40  to allow for the existence of such overlapped areas  440  so as to avoid the possibility of having unirradiated areas on the silicon thin film  52 . The width of the overlapped areas  440  can be, e.g., 1 μm. Other width of the overlapped areas  440  may also be used (e.g., 0.5 μm, 1.5 μm, 2 μm, etc.) 
   The third areas  445  preferably extend along a line Q (in the Y-direction) which is parallel to the centerline P, along which the first areas  410  and the second areas  435  extend, and offset therefrom by approximately 0.75 μm. In addition, the bottom edge  436  of each of the second areas  435  is offset with respect to the Y-direction by 505 μm from the bottom edge  446  of the respective third area  445 . The top edge  437  of each of the second areas  435  is offset in the Y-direction by 5 μm from the bottom edge  446  of the respective third area  445 . Because of such configuration of the second areas  435  and the third areas  445 , the third areas  445  overlap certain portions  450  of the re-solidified first areas  410  melted by the first masked irradiation beam pulse. Therefore, the silicon thin film  52  in these portions  450 , which were overlapped by the third areas  445 , are again completely melted throughout its thickness along with the previously unmelted regions. 
     FIG. 5D  shows the cooling, re-solidification, grain growth and crystallization of the completely melted silicon thin film  52  provided in the second and third areas  435 ,  445 , the overlapped areas  440  and the portion  450 , and the previous melted regions. With reference to the second areas  435 , each of these areas  410  re-solidifies and crystalizes to form two columns of grains  460 ,  465  that are seeded and grown towards one another from the adjoining unmelted regions  455 . The two columns  460 ,  465  abut one another along a respective one of a plurality of grain abutment boundaries  468  after the abutting grains have grown by a characteristic growth distance of approximately 1.5 μm. Both columns  460 ,  465  in each of the second re-solidification areas  435  have a respective central portion in which grain boundaries form large angles (e.g., approximately 90°) with respect to the second irradiation path  315 . 
   In the melted third areas  445  that adjoin respective non-overlapped portions of the first areas  410 , which have been previously irradiated and re-solidified, the grains in such non-overlapped portions of the first areas  410  seed grain growth in the adjoining region of the third areas  445  until grains growing in the opposite directions in the third areas  445  abut one another at a grain abutment boundaries  470 . In this manner, the grains of the first areas  410  of grains  420 ,  425  of silicon thin film  52  in the first areas are extended into the third areas  445  so as to increase the lengths of the grains. 
   Similarly to the discussion above with reference to  FIG. 5B , while re-solidification of the second and third melted areas  435 ,  445  is taking place, the sample  40  is being continuously translated with respect to the stationary irradiation beam pulse  164  along the second irradiation path  315 . In particular, the sample  40  is translated so that another area of the silicon thin film  52  is irradiated by a third radiation beam pulse having the intensity pattern  235  shown in  FIG. 3 , and the sample  40  is translated so as to only partially overlap certain regions of the re-solidified second and third areas  435 ,  445  by the third irradiation beam pulse. The timing of the generation of the third irradiation beam pulse is controlled in the similar manner as the control of the generation of the second pulse described above. 
   Turning to  FIG. 5E , the third radiation laser pulse is generated so that the first slit-shaped beamlets  255  irradiate and completely melt fourth areas  475  of the silicon thin film  52  in the first column  210 , and the second slit-shaped beamlets  265  completely melt fifth areas  485  of the silicon thin film  52  in the first column  210 . The fourth areas  475  preferably extend in the same direction as the first areas  410  which are illustrated in FIG.  5 B. Similarly to the second areas  435  of  FIG. 5C , the fourth areas  475  are provided at a distance from the second areas  435  in the negative Y-direction which is slightly less than the length of the second areas  435  (i.e., slightly less than ½ nm). Overlapped areas  490  provided between the second areas  435  and the fourth areas  475 , and overlapped areas  495  provided between the third areas  445  and the fifth areas  485  are small sections of the first and second areas, respectively, which were re-solidified but again completely melted by the first and second slit-shaped beamlets  255 ,  265  of the further intensity profile  405  of the masked irradiated beam pulse  164 , respectively. The computer  106  controls the timing of the pulses and the translation of the sample  40  to allow for the creation of such overlapped areas  490 ,  495  in order to avoid the possibility of having unirradiated areas on the silicon thin film  52 . The width of the overlapped areas  490 ,  495  is similar to that of the overlapped areas  440 . 
   The positional relationship between the fourth and fifth areas  475 ,  485  is substantially the same as the positional relationship between the second and third areas  435 ,  445 , the details of which are described above. Due to such configuration, the fifth areas  485  overlap certain portions  497  of the third re-solidified areas  445 . Therefore, the silicon thin film  52  in these portions  497  (which were overlapped by the fifth areas  485 ) is again completely melted. 
     FIG. 5F  shows the re-solidification and grain growth in the previously completely melted fourth and fifth areas  475 ,  485  and the overlapped areas  490 ,  497 . The description of the re-solidification and lateral growth provided above with reference to  FIG. 5D  is equally applicable herein. In particular, as the fourth areas  475  are re-solidified, and the controlled grain lateral growth occurs therein that is seeded from their edges, two columns of grain formations  500 ,  505  are formed, thus effectively extending the columns  460 ,  465 , respectively. With respect to the fifth areas  485 , two columns of grain formations  510 ,  515  are also formed in a similar manner. Thus, the controlled lateral grain growth of the silicon thin film  52  is further extended along the first column  210  to include the previously and completely melted silicon thin film  52  provided in the fourth and fifth areas  475 ,  485 . 
   As the sample  40  is continuously translated and the first column  210  of the silicon thin film  52  is irradiated by the masked irradiated beam pulse  164  along the second path  315 , further areas of the silicon thin film  52  on the first column  210  are melted consistent with the melting configuration of the areas  435 ,  445  and the areas  475 ,  485 , and the controlled sequential lateral solidification and grain growth in all such further areas of the first column  210  is effectuated. Thus, all portions of the silicon thin film  52  in the entire first conceptual column  210  of the sample  40  between the top edge  45  and the bottom edge  47  of the sample  40  are subjected to the continuous motion SLS. Since all areas in the first column  210  have been irradiated and subjected to the SLS, there is no need to further re-irradiate any portion of the silicon thin film  52  provided therein. In particular, the end product of such continuous motion SLS for the first column  210  is illustrated in  FIG. 5G , which shows that when the cooling and re-solidification of all melted areas  410 ,  435 ,  445 ,  475 ,  485 , etc. is completed, a re-solidification region  520  is formed having contiguous columns  510  of relatively long grains, along with grain boundaries oriented generally along the X-direction. This is an improvement over the prior SLS methods which require microtranslations of the sample  40  to be performed while each respective column of such sample is irradiated using the radiation beam pulse. Such microtranslations require the continuous translation of the sample to be slowed to a stop, the sampled to be microtranslated, then to increase the speed of the translation of the sample via the sample translation stage to reach a predetermined velocity, and to continue with the translation of the sample while irradiating the particular column of the silicon thin film. 
   Turning back to  FIG. 4 , when the sample  40  is translated so that the fixed position of impingement of the masked irradiated beam pulse  164  reaches a bottom edge  47  of the sample  40  at a location  320  with respect to the position of the sample  40 , the translation of the sample  40  is slowed along a third path  325  until the sample  40  comes to a full stop when the fixed position of impingement of the radiation beam pulse  164  is at a location  330  with respect to the position of the sample  40 . In the present embodiment, the predetermined pulse repetition rate is, for example, 250-300 pulses/sec (which is preferable for the excimer laser  110  used herein) and each pulse provides a beamlet intensity of approximately 500 mJ/cm 2  with a pulse duration of approximately 30 nseconds. 
   After the stationary irradiation beam pulse  164  in the frame of reference of the translating sample  40  has come to a stop at the location  330 , the sample  40  translated in the X direction under the control of the computer  106  so that the pulsed irradiation beam pulse  164  traces a fourth path  335  until the masked irradiation beam pulse  164  impinges the sample  40  at a location  340 . The sample  40  is then accelerated in the −Y direction so that the pulsed irradiation beam traverses a fifth path  345  such that the sample  40  reaches the predetermined velocity of translation by the time the bottom edge  47  of the sample  40  reaches a position  347  of impingement of the masked irradiated beam pulse  164 . Thereafter, the sample  40  is continuously translated at the predetermined velocity in the −Y direction for the entire length of a sixth irradiation path  350 , while the masked irradiation beam pulse  164  sequentially irradiates the metal layer  52  on second column  220  of the sample  40  at the predetermined pulsed repetition rate. 
   Referring to  FIG. 6A , there is shown a portion  540  of the silicon thin film  52  in the second conceptual column  220  immediately above the lower edge  47  of the sample  40 , after the translation of the sample  40 , so that it is impinged by the masked irradiated beam pulse  164  along the sixth path  250 . The portion  540  of the silicon thin film  52  in the second column  220  is first irradiated using the second slit-shaped beamlets  265 , and areas  550  of the portion  540  are completely melted throughout their entire thickness. This is because the portion of the intensity profile of the masked irradiated beam pulse  164  which irradiates and completely melts the areas  550  using the second beamlet section  260  having the second slit-shaped beamlets  265  provided in the configuration that was described above. At this point in the process, the first slit-shaped beamlets  255  do not irradiate the second column  220  of the sample  40  because they are irradiated outside the boundaries of the sample  40  (i.e., below the bottom edge  47 ). It should be noted that a small strip  550  of a particular area  550 , which is adjacent to the re-solidification region  520  of the first conceptual column  210 , slightly overlaps a small portion  555  of the re-solidification region  520  along the length of such area  550  (e.g., for ½ mm). Prior to the irradiation by the second slit-shaped beamlets  265 , when the masked irradiated beam pulse  164  impinges the sample  40  along the sixth path  350 , this small portion  555  is subjected to the irradiation and SLS in the first column  210  of the sample. The small portion  555  corresponds to a initial section of the overlapping portion  230  shown in FIG.  4 . The irradiated and melted silicon thin film  52  of the areas  550  are separated by the shadow areas  560 . As described above, the reason that these areas  560  were not irradiated is because the first shadow regions  267  of the intensity pattern  235  of the masked irradiated beam pulse  164  did not irradiate and melt the areas  560 . 
   The silicon thin film  52  provided in the areas  550  cool and re-solidify to effect lateral grain growth therein starting from their respective edges. In particular, each area  550  has two abutting columns of grains  570 ,  575  (shown in  FIG. 6B ) which extend along the entire length of the respective area  550 . As described above with respect to the SLS of the first column  210 , the grain growth is initiated from and seeded from the shadow areas  560  toward a center of the respective areas  550 . With respect to the particular area  550  which has the small overlapping area  555 , the grains of neighboring completed portion  565  seed and laterally grow into that particular area  550 . 
   Turning to  FIG. 6B  as the areas  550  cool and re-solidify, the sample  40  is continuously translated in the negative Y-direction at the predetermined velocity along the sixth path  350 , and another portion of the silicon thin film  52  in the second conceptual column  220  is irradiated. Since the masked irradiated beam pulse  164  impinges the silicon thin film  52  along the sixth path  350  while the sample  40  is translated by the computer  106  as described above, the second slit-shaped beamlets  265  irradiate and completely melt the silicon thin film  52  in areas  580 . As discussed above with reference to  FIGS. 5C and 6A , each of the areas  580  has a small area  582  which overlaps a portion of the previously irradiated and re-solidified respective area  550 . In addition and as described above with reference to  FIG. 6A , the particular area  580  bordering the re-solidification region  520  has a small area  583  which overlaps and melts a portion  584  thereof. In addition, the first slit-shaped beamlet  255  irradiate and completely melt the silicon thin film  52  in the areas  585 . A small area  583  corresponds to a portion of the overlapping portion  230  shown in  FIG. 4  which is subsequent to the small area  555  illustrated in FIG.  6 A. 
   As further shown in  FIG. 6B , the areas  585  are provided at a distance from the areas  580  (in the negative Y-direction) slightly greater than the entire length of the areas  580 . The configuration of the areas  580 ,  585  with respect to one another is substantially similar to the configuration of the areas  435 ,  445  described above and shown in FIG.  5 C. Thereafter, the areas  580 ,  585  cool and re-solidify in a substantially the same manner described above with reference to in  FIG. 5C , only that the SLS for the silicon thin film  52  provided in the second column  220  of the sample if effectuated from the bottom edge  47  of the sample  40 , instead of from the top edge  45  as provided for the first column  210 . 
   Again turning back to  FIG. 4 , when the sample  40  is translated in the −Y direction so that the fixed position of impingement of the masked irradiated beam pulse  164  reaches the top edge  45  of the sample  40 , the translation of the sample  40  is slowed along a seventh path  355  until the sample  40  comes to a fill stop when the fixed position of impingement of the radiation beam pulse  164  on the sample  40  is at a location  360  with respect to the sample  40 . After the stationary irradiation beam pulse  164  in the frame of reference of the translating sample  40  has come to a stop at the fourth location  360  (i.e., the translation of the sample  40  is stopped), the sample  40  is translated in the negative X-direction under the control of the computer  106  so that the masked irradiated beam pulse  164  traces an eighth path  365  until the masked irradiated beam pulse  164  impinges a location  370  outside the boundaries of the sample  40 . The sample  40  is then accelerated in the Y-direction so that the masked irradiated beam pulse  164  traverses another path which is substantially parallel to the second irradiation path  315  (i.e., the sample  40  is again translated in the Y-direction). This procedure continues until the silicon thin film  52  provided in all conceptual columns of the sample  40  are irradiated, and the SLS is successfully effectuated therein. 
   As described above, each such translation of the sample  40  and the irradiation thereof is performed for every conceptual column of the sample  40 . Thus, if the sample  40  is conceptually subdivided into 15 columns, the sample  40  is continuously translated in the Y-direction or the negative Y-direction 15 times. The results of the single step, continuous motion SLS according to the present invention is shown in FIG.  7 . This drawing illustrates the end product of the sample  40  whose every area of the silicon thin film  52  extending along the entire periphery of the sample  40  is irradiated to promote the controlled SLS and grain growth thereon. 
   It is preferable to use a high aspect homogenized irradiation beam, i.e., having a wide and thin intensity profile in the direction of the translation of the sample  40 . In particular, when such intensity is utilized, it takes less steps to irradiate all columns of the sample  40 . There are also timing advantages to the utilization of the above-described embodiment of the method according to the present invention. Generally, the total process time T PROCESS  to irradiate and process the silicon thin film  52  provided on the entire sample  40  is calculated as follows:
 
 T   PROCESS   =T   CRYSTALIZATION   +T   WASTED   (3)
 
where: 
                 T   CRYSTALIZATION     =           A   TOTAL       A   BEAM       ×   n       f   LASER         ,           (   4   )             
 
A TOTAL  is the total area of the sample  40  (e.g., 40 cm×30 cm=1200 cm 2 ), A BEAM  is a beam area (e.g., 2 cm×1 mm=20 mm 2 ), and n is a number of shots fired at a particular point (e.g., for a two shot process illustrated in  FIGS. 5A-5G  and  6 A- 6 B, n=2). In the present embodiment, the crystallization time for each column is approximately 1 second. Therefore, the total time of crystallization for the sample having 15 columns is 15 second. Next, the wasted time should be evaluated. For example,
 
 T   WASTED   =n   STEP   ×T   STEP ,  (5)
 
where n STEP  is the number of times the sample is stepped to the next column (e.g., for 15 columns, the sample is stepped 14 times), and T STEP  is the time required for each such stepping (e.g., 0.3 seconds). Thus, T WASTED  is 14×0.3 seconds=4.2 seconds for the sample  40 . To compare this result with the time wasted for the method and system described in the &#39;585 application, while the crystallization time of each column of the sample  40  is the same for the system and method of the present invention and that of the &#39;585 application (due to a reduction of the sample velocity in the present invention by half as compared to the velocity of the sample described in the &#39;585 application), the wasted time of the system and method of the &#39;585 application is higher than that of the system and method of the present invention. This is because the system and method of the present invention does not require the sample  40  to be microtranslated (as described in the &#39;585 application) when the masked irradiated beam pulse  164  is impinging a location outside of the periphery of the sample  40 . Therefore, according to the present invention, the microtranslation time is not at issue because the sample  40  is not microtranslated. Thus, if the sample of &#39;585 application is subjected to one microtranslation per column thereof, the time wasted not crystalizing the silicon thin film on the sample is 14 columns×0.3 seconds=4.2 second for microtranslations and 4.2 seconds for regular translations of the entire sample. Thus, the time savings to crystalize each sample using the system and method of the present invention is reduced by, e.g., 4.2 seconds as compared to the system and method of the &#39;585 application.
 
     FIG. 8  shows an enlarged illustration of a second exemplary embodiment of an intensity pattern of the irradiated beam pulse as defined by a further mask  150  utilized by the system and method of the present invention as it impinges the silicon thin film on the substrate, which promotes a larger grain growth on the silicon thin film. This exemplary intensity pattern  600  includes slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609 ,  611 ,  613 ,  615 ,  617 ,  619 , etc. provided in a stepped manner. The width of the slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609 ,  611 ,  613 ,  615 ,  617 ,  619  along the X-direction can be the same as that of the first slit-shaped beamlets  255  of the intensity pattern  235  (e.g., 3 μm), and the length of these slit-shaped beamlets can be, e.g., 0.2 μm. Other sizes and shapes of the slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609 ,  611 ,  613 ,  615 ,  617 ,  619 , etc. are conceivable, and are within the scope of the present invention. 
   In particular, the slit-shaped beamlet  601  is provided in a top-rightmost corner of the intensity pattern  600  The slit-shaped beamlet  603  is provided at an offset, in the −X direction, from the slit-shaped beamlet  601 . In particular, a top edge  630  of the slit-shaped beamlet  603  extends slightly above a line A on which the center  602  of the slit-shaped beamlet  601  extends. Similarly, the slit-shaped beamlet  605  is provided at an offset (in the −X direction) from the slit-shaped beamlet  603  so that a top edge  631  of the slit-shaped beamlet  605  extends slightly above a line B on which the center  604  of the slit-shaped beamlet  603  extends. The same applies for the position of the slit-shaped beamlet  607  with respect to the slit-shaped beamlet  605 , and the slit-shaped beamlet  609  with respect to slit-shaped beamlet  607 . The slit-shaped beamlets  611 ,  613 ,  615 ,  617  and  619  are arranged in a substantially the same configuration as the slit-shaped beamlet  601 ,  603 ,  605 ,  607 ,  609 , except that while the starting location of the slit-shaped beamlet  611  is the same as of the slit-shaped beamlet  601  along the Y-direction, the slit-shaped beamlet  611  is offset along the X-direction by a particular length  635 . According to an exemplary embodiment of the present invention, the top edge  634  of the slit-shaped beamlet  611  is provided slightly above a line C on which the bottom edge  633  of the slit-shaped beamlet  609  extends. The configuration of the intensity pattern  600  is provided such that the first row  640  of the intensity pattern  600  (consisting of the slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609 ) is provided above the second row  641  of the intensity pattern  600  (consisting of the slit-shaped beamlets  611 ,  613 ,  615 ,  617 ,  619 ) along the −X direction, followed by the third row  642 , etc. The intensity pattern  600  can include a large number of rows of slit-shaped beamlets, e.g.,  100 ,  1000 , etc., depending on the width of the irradiation laser beam  149  impacting the mask  150 , and the configuration of the slits and opaque regions of the mask  150 . 
     FIG. 9  shows the grain structure of a portion of an exemplary first conceptual column  210  of the sample  40  having the silicon thin film  52  therein, as the intensity pattern  600  of the masked irradiated beam pulse  164  of  FIG. 8  impinges the respective portions of the silicon thin film  52 , at an exemplary stage of SLS processing according to a second exemplary embodiment of the method of the present invention. Using the exemplary embodiment of the method shown in  FIG. 9 , longer grains can be grown on the silicon thin film  52 . This exemplary embodiment of the method according to the present invention can be implemented in a substantially the same manner as the embodiment described above with reference to  FIGS. 4 ,  5 A- 5 G and  6 A- 6 B, while utilizing the intensity pattern  600  instead of the intensity pattern  235  to irradiate, and completely melt the silicon thin film  52  in the first conceptual column  210  of the sample  40 . 
   In particular,  FIG. 9  illustrates this exemplary embodiment when the silicon thin film  52  in the first conceptual column  210  of the sample  40  is irradiated by the intensity pattern  600 , while the sample  40  is continuously translated in the Y-direction. The silicon thin film  52  in the areas  650 ,  652 ,  654 ,  656 ,  658 ,  660 ,  662 ,  664 ,  666 ,  668 , etc. of the first conceptual column  210  of the sample  40  are completely melted throughout its thickness. It should be understood that these particular areas are being irradiated because the slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609 ,  611 ,  613 ,  615 ,  617 ,  619 , etc. of the intensity pattern  600  of the masked irradiated beam pulse  164  impinged such areas  650 ,  652 ,  654 ,  656 ,  658 ,  660 ,  662 ,  664 ,  666 ,  668 , etc. to completely melt the silicon thin film  52  provided therein (i.e., throughout the thickness of the silicon thin film  52 ). 
   The silicon thin film  52  provided in most of the areas  650  was not subjected to the previous lateral solidification. With the respect to the area  652 , the slit-shaped beam  603  impinging on the silicon thin film  52  provided in this area  652  melts more than half of the re-solidified section of corresponding to the location thereof (which was previously irradiated by the slit-shaped beamlet  601 ). In particular, the top edge of the area  652  is provided slightly above a line M on which a boundary  644  extend along the M-axis, the boundary  644  being formed by the previous irradiation and grain growth by the slit-shaped beamlet  601 . It should be understood that due to such position of the area  652 , the center  653  thereof is provided above a line N along which a lower edge of the area  650  extends. Similarly, the center  655  of the area  654  is positioned slightly above an axis along with the lower edge of the area  652  extends, the center  657  of the area  656  is positioned slightly above a line along with the lower edge of the area  654  extends, and the center  659  of the area  658  is positioned slightly above an axis along with the lower edge of the area  656  extends. Therefore, the areas  650 ,  652 ,  654 ,  656 ,  658  are provided in a configuration which substantially corresponds to that of the slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609  of the first row  640  of the intensity pattern  600  of the masked irradiated beam pulse  164 . 
   The areas  660 ,  662 ,  664 ,  666 ,  668 , in which the silicon thin film  52  is completely melted throughout its thickness, are arranged in a substantially the same configuration as that of the areas  650 ,  652 ,  654 ,  656 ,  658 , except that the area  660  is provided at an offset, along the −X direction, from the area  650 , with the distance of the offset being approximately equal to the distance  635  between the slit-shaped beamlet  601  and the slit-shaped beamlet  611  as described above with reference to FIG.  8 . In addition, the area  658  has a small portion  670  which overlaps the region of the silicon thin film  52  which was previously irradiated by the slit-shaped beamlet  611 . It is preferable to utilize this small portion  670  such that the small grain regions provided at the edges of the re-solidified areas of the silicon thin sample  52  are minimized or even eliminated. 
     FIG. 10  shows the progression of the SLS of the first column  210  using the mask of  FIG. 8  as the sample  40  is continuously translated along the Y-direction. In this manner, a number of rows  710 ,  720 ,  730 , etc. of the silicon thin film  52  in the first conceptual column  210  are produced. The number of these rows  710 ,  720 ,  730 , etc. corresponds to the number of the rows  640 ,  641 ,  642 , etc. of the intensity pattern  600  illustrated in FIG.  8 . Similarly to the method of  FIG. 4 , when the sample  40  is translated so that the masked irradiated beam pulse  164  reaches the lower edge  47  of the sample  40 , and the masked irradiated beam pulse  164  no longer impinges the silicon thin film  52  provided on the sample  40 , the sample is translated in the X-direction to reach a particular location to position the sample  40  for further translation so that the irradiation beam  164  may impinge the silicon thin film  52  in the second conceptual column  220  of the sample  40 . Thereafter, the sample  40  is translated in the −Y direction and the silicon thin film  52  in the second conceptual column  220  of the sample  40  is irradiated in a substantially the same manner as provided above with reference to  FIGS. 9 and 10 . However, the slit-shaped beamlets  609 ,  619  (and not the slit-shaped beamlets  601 ,  611 ) first irradiate the silicon thin film  52  in the second conceptual column  220 , starting from the lower edge  47 , and completing the irradiation of the second column of the sample  40  at the top edge  45 . In this manner, the silicon thin film  52  in all conceptual columns of the sample  40  can be effectively subjected to the continuous motion SLS, with longer grains being grown thereon. 
   The exemplary velocity V to translate the sample  40  and irradiate it using the intensity profile  600  of the masked irradiated beam pulse  164  illustrated in  FIG. 8  is provided as follows:
 
 V=L   B   *f   LASER   (6)
 
where L B  is the width of one of the slit-shaped beamlets  601 ,  603 ,  605 ,  607 ,  609 ,  611 ,  613 ,  615 ,  617 ,  619 , etc. of the intensity pattern  600  shown in  FIG. 8 , and f LASER  is the frequency of the irradiation beam  149  emitted by, e.g., the excimer laser  110 . In the exemplary embodiment illustrated in  FIG. 8 , LB equals to 0.2 mm, and f LASER  can equal to 300 hertz. Thus the exemplary velocity V of the sample translation can equal to 60 mm/seconds for five (5) beamlets provided in each row  640 ,  641 ,  642 , etc. of the intensity pattern  600 . According to the exemplary embodiment of the present invention, if the number of slit-shaped beamlets of the intensity profile  600  per row increases to, e.g., ten (10) slits, then the length of each slit-shaped beamlet is preferably reduced by half to, e.g., 0.1 mm. Therefore, with 10 slit-shaped beamlets per column of the intensity pattern  600  and using the above calculations, the velocity of the sample translation is equal to 30 mm/second. However, using a higher number of the slit-shaped beamlets in a single row of the intensity pattern  600 , it is possible to obtain longer grains on the silicon thin film  52  of each conceptual column of the sample  40 .
 
     FIG. 11  shows an enlarged illustration of a third exemplary embodiment of an intensity pattern  800  of the irradiation beam pulse as defined by another mask  150  utilized by the system and method of the present invention as it impinges the silicon thin film on the substrate. Similar to the intensity pattern  235  of  FIG. 3 , the intensity pattern  800  includes the first beamlet section  250  and the second beamlet section  260 . In addition, the intensity pattern  800  includes one reduced intensity section  810  bordering the second beamlet section  260 . The reduced intensity portion  810  has only 70% of the intensity of the homogenized irradiation beam  149 , and can be generated by a gray-scale portion of the mask  150  by irradiation the homogenized irradiation beam  149  through such gray-scale portion of the mask  150 . This reduced intensity portion  810  does not melt an area of the silicon thin film  52  which it impacts throughout the entire thickness thereof; indeed, this reduced intensity portion  810  of the masked irradiated beam pulse  164  only partially melts the area of the silicon thin film  52  that it irradiates. 
   The intensity pattern  800  shown in  FIG. 11  can be used for irradiating the sample  40  via the exemplary embodiment of the method according to the present invention illustrated in  FIGS. 5A-5G  and  6 A- 6 E. Due to the presence of the reduced intensity portion  810  in the intensity pattern  800 , the width of the cross-section of the masked irradiated beam pulse  164  can be approximately 1.5 mm (as opposed to having the width of the masked irradiated beam pulse  164  being 1 mm as provided for the intensity pattern  235  of  FIG. 3 ) so as to utilize all areas of the intensity pattern  800 , including the reduced intensity portion  810 . However, while the width of the masked irradiated beam pulse  164  is increased, the sample  40  may be translated at the same predetermined velocity as the velocity used with the intensity pattern  235  with reference to  FIGS. 4 ,  5 A- 5 G and  6 A- 6 B. 
   The illustration of the continuous motion SLS process according to the present invention using the intensity pattern  800  is substantially the same as for the intensity pattern  235  for the first two irradiation beam pulses impacting the silicon thin film  152  as provided above with reference to  FIGS. 5A-5D . However, for the third irradiation beam pulse shown in  FIG. 5E , the area labeled as  820  would be completely irradiated using the reduced intensity portion  810  of the intensity pattern  800 . While the area  820  is irradiated by the reduced intensity portion  810  of the intensity pattern  820 , it is only partially melted. Thereafter, the area  820  re-solidifies while maintaining the integrity of the grains grown therein. This partial melting is advantageous because upon re-solidification of the area  820 , the surface thereof is flattened, and thus peaks and valleys on this surface are minimized. This procedure continues for the first conceptual column  210  of the sample  40  until the sample  40  is continuously translated so that the masked irradiated beam pulse  164  just passes the bottom edge  47  of the sample  40 . 
   The procedure described above with reference to  FIG. 4  is continued in a substantially the same manner as described above which utilizes the intensity pattern  235 . However, according to this embodiment of the method according to the present invention which utilizes the intensity pattern  800  for irradiating the silicon thin film  52  provided on the sample  40 , after the masked irradiated beam pulse  164  stops impinging any area of the first column  210  of the sample  40 , and before it starts impinging the second column  220  of the sample  40 , the reduced intensity portion  810  of the intensity pattern  800  is placed such that when the masked irradiated beam pulse  164  starts irradiating the second conceptual column  220  of the sample  40 . Thus, the reduced intensity portion  810  of the intensity pattern  800  of the masked irradiated beam pulse  164  is provided at the back of the two beamlet sections  250 ,  260  of the intensity pattern  800 . This can be done by, e.g., rotating the mask  150  by 180°. In this manner, the reduced intensity portion  810  can partially irradiate the previously-irradiated and re-solidified areas of the second column  220  (i.e., already subjected to the SLS via the beamlets of the first and second beamlet sections  250 ,  260  of the intensity pattern  800 ). Upon reaching the top edge  45  of the sample, the reduced intensity portion  810  of the intensity pattern  800  can again be placed in the same configuration as was utilized when the first conceptual column  210  of the sample  40  was being irradiated by the masked irradiated beam pulse  164  (e.g., by rotating the gray-scale portion of the mask  150  by 180°). In this manner, the silicon thin film  52  of the entire sample  40  can be effectively subjected to the continuous motion SLS, while flattening the surface of the irradiated, re-solidified and crystalized silicon thin film  52  on the entire periphery thereof. 
     FIG. 12  shows an enlarged illustration of a fourth exemplary embodiment of an intensity pattern  830  of the irradiated beam pulse as conceptually defined by yet another mask utilized by the system and method of the present invention. as it impinges the silicon thin film on the substrate. Similar to the intensity pattern  800  of  FIG. 3 , the intensity pattern  830  includes the first beamlet section  250 , the second beamlet section  260  and a first reduced intensity section  810  bordering the second beamlet section  260 . In addition, the intensity pattern  830  includes second reduced intensity section  810  bordering the first beamlet section  250 . As with the first reduced intensity portion  810 , the second reduced intensity portion  840  has only 70% of the intensity of the homogenized irradiation beam  149 , and can be generated by another gray-scale portion of the mask  150  by irradiation the homogenized irradiation beam  149  there through. 
   It should be understood that the intensity pattern illustrated in  FIG. 12  is shown as if both first and second reduced intensity portions  810 ,  840  are being used for irradiating the silicon thin film  52  provided on the sample  40 . However, as shall be described in further detail below, only one of these reduced intensity portions  810 ,  840  of the intensity pattern  830  are to be used for such irradiation. 
   The intensity pattern  830  shown in  FIG. 12  can be used for irradiating the silicon thin film  52  with the method according to the present invention in a similar manner as described above with reference to the use of the intensity pattern  800  of FIG.  11 . Again, the width of the cross-section of the masked irradiated beam pulse  164  is also approximately 1.5 mm. In particular, when the sample  40  is continuously translated so that the masked irradiated beam pulse  164  irradiates the first conceptual column  210 , only the first beamlet section  250 , the second beamlet section  260  and the first reduced intensity portion  810  of the intensity pattern  830  of the masked irradiated beam pulse  164  is irradiated and impinges the silicon thin film  52  on the sample  40 , while the second reduced in tensity portion  840  is not utilized. Then, the procedure for the SLS of the first conceptual column  210  continues in substantially the same manner as the procedure described above for the first conceptual column  210  which uses the intensity pattern  800 . 
   Then, after the masked irradiated beam pulse  164  stops impinging any area of the first conceptual column  210 , and before it starts impinging the second conceptual column  220  of the sample  40 , the mask  150  is positioned or shifted in the Y-direction by the mask translation stage such that the second reduced intensity portion  840  of the intensity pattern  830  is utilized when the masked irradiated beam pulse  164  starts irradiating the second conception column  220  of the sample, while not utilizing the first reduced intensity portion  810  for any irradiation of the silicon thin film  52  in the second conceptual column  220  of the sample. In this manner, the second reduced intensity portion  840  of the intensity pattern  830  of the masked irradiated beam pulse  164  is provided at the back end of the first and second sections  250 ,  260  of the intensity pattern  830  of the masked irradiated beam pulse  164  to irradiate the silicon thin film  52  in the second conceptual column  220  of the sample  40 . Upon reaching the top edge  45  of the sample  40 , the mask  150  is positioned or shifted in the negative Y-direction by the mask translation stage so that the intensity pattern  830  is provided in the same configuration as was utilized when the first conceptual column  210  of the sample  40  was irradiated by the masked irradiated beam pulse  164 . 
     FIGS. 13A-13D  show the radiation beam pulse intensity pattern and the grain structure of a portion of an exemplary first conceptual column of a silicon thin film  52  on the sample  40  at various sequential stages of SLS processing according to another exemplary embodiment of the method of the present invention. In this exemplary embodiment, the silicon thin film  52  of the entire sample  4 C has already undergone the continuous motion SLS, and then rotated 90° in a clock-wise direction by the sample translation stage  180  (i.e., controlled by the computer  106 ). After such rotation, the sample  40  is again conceptually subdivided into, e.g., 15 columns, the sample  40  is translated in the same manner as described above with reference to  FIGS. 4 ,  5 A- 5 G and  6 A- 6 B. 
   In particular,  FIG. 13A  shows melted areas  860  of a first conceptual column  850  which were irradiated by the beamlets  255  of the first beamlet section  250  of the intensity pattern  235  illustrated in  FIG. 3 , as the sample  40  is continuously translated the Y-direction. As discussed above for the areas  210  in reference to  FIG. 5A , the areas  860  are melted throughout their entire thickness. Contrary to the areas  210 , the areas  860  of the first column  850  were previously subjected to the SLS prior to their melting. Then, as shown in  FIG. 13B , the areas  860  cool, re-solidify and re-crystalize. The grain seeding and growth takes place starting from the borders of the areas  860 . In this embodiment, because the silicon thin film  52  of the sample  40  had already underwent the SLS, the grains provided at the edges of the areas  860  (which were grown in the controlled manner) seed the areas  860 , and start growing into the re-solidifying areas  860  to form areas  865  which have larger areas of single grain growth. The procedure continues as shown in  FIG. 13C  such the sample  40  is translated in the Y-direction and irradiated in a substantially similar manner as described above with reference to FIG.  5 C. Similarly to the areas  435 ,  445 , certain areas  870 ,  875  of the silicon thin film  52  in the first conceptual column  850  are melted. As with the areas  435 ,  445 , particular portions of the areas  870 ,  875  overlap certain portions of the previously irradiated and re-solidified areas  865  of FIG.  13 B. As shown in  FIG. 13D , upon cooling and re-solidification of the areas  870 , the lateral grain growth is seeded and promoted from their borders using the grains grown using the process described above with reference to  FIGS. 5A-5G  to form the resultant areas  885 . With respect to the cooling, re-solidification and re-crystallization of the areas  875 , the grain growth in the resultant areas  880  is promoted using the grains of the re-solidified areas  865  provided at the borders of the areas  875 . According to the procedure described above with reference to  FIGS. 13A-13D  as it relates to the technique described above with reference to  FIGS. 5A-5G  and  6 A- 6 B, its is possible to effectuate the SLS which provides larger regions  900  of single grains on the silicon thin film  52  of the sample  40 , as illustrated in FIG.  14 . 
   Referring next to  FIG. 15 , there is shown a flow diagram of exemplary steps carried out with the aid of the computer  106  (or other control devices) for the single-step, continuous motion SLS processing in accordance with the present invention to control the shape and size of grains, and the location and orientation of grain boundaries in the silicon thin film  52  of the sample  40 . As shown in the flow diagram of  FIG. 15 , in step  1000  the hardware components of the system of  FIG. 1 , such as the excimer laser  110 , the beam energy density modulator  120 , the beam attenuator  130  and the shutter  152  are first initialized at least in part by the computer  106 . A sample  40  is loaded onto the sample translation stage  180  in step  1005 . It should be noted that such loading may be performed either manually or automatically using known sample loading apparatus under the control of the computer  106 . Next, the sample translation stage  180  is moved, preferably under the control of the computer  106 , to an initial position in step  1010 . The various other optical components of the system are adjusted manually or under the control of the computer  106  for a proper focus and alignment in step  1015 , if necessary. The radiation beam pulses  164  are then stabilized in step  1020  to a desired intensity, pulse duration and pulse repetition rate. In step  1021 , it is determined whether a next radiation beam pulse irradiates the silicon thin film  52  after each melted region thereof has completely re-solidified following the irradiation by a previous radiation beam pulse. If not, in step  1022 , the pulse repetition rate of the excimer laser  110  is adjusted. In step  1024  it is determined whether each beamlet of the intensity pattern of each radiation beam pulse has sufficient intensity to melt each one of the silicon thin film  52  overlapped thereby throughout its entire thicknesses without melting an adjacent region overlapped by a shadow region of the intensity pattern. If under-melting or over melting occurs, in step  1025 , the attenuator  130  is adjusted so that each radiation beam pulse has sufficient energy to fully melt the metal layer in irradiated areas without over melting adjoining unirradiated regions. 
   In step  1027 , the sample  40  is positioned to point the masked irradiated beam pulse  164  at the first conceptual column  210  of the sample  40 . In step  1030 , the current column of the sample  40  is irradiated using the radiation beam pulse  164  having an intensity pattern controlled by the mask  150 ,  700 ,  800 ,  830 . In step  1035 , the sample  60  is continuously translated so that the masked irradiated beam pulse  164  irradiates the silicon thin film  52  along the current column of the sample  40  in a predetermined direction. 
   In step  1045 , it is determined whether all conceptual columns of the sample  40  having the silicon thin film  52  provided thereon have been subjected to the SLS processing. If not, the sample  40  is translated to the next unirradiated conceptual column of the sample  40 , and the process loops back to step  1030  for a further translation along a predetermined direction (e.g., an opposite direction), and for the irradiation of the next conceptual column of the sample  40  by the radiation beam pulse  164 . If the SLS processing has been completed for all columns of the sample  40 , the hardware components and the beam of the system shown in  FIG. 1  can be shut off (step  1055 ), and the process terminates. 
   The foregoing exemplary embodiments merely illustrate the principles of the present invention. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein without departing from the scope of the invention, as defined by the appended claims.