JP4211939B2 - Method for manufacturing polycrystalline film using laser - Google Patents

Description

The present invention relates to a method for manufacturing a crystal film and a crystal film, and more particularly, to a method for manufacturing a crystal film in which a laser beam is incident on an amorphous film to crystallize, and the manufactured crystal film.
The crystal film can be used for a low-temperature polycrystalline TFT liquid crystal display, a solar battery panel, a paper-type liquid crystal display, an organic EL display, and the like.

A sequential lateral solidification (SLS) technique is known in which an excimer laser is incident on an amorphous silicon thin film to repeatedly melt and solidify and grow crystals in the lateral direction (in-plane direction of the thin film). Hereinafter, the conventional SLS technique will be described.
After elongating the cross section of the pulse laser beam, it passes through, for example, a slit having a width of 3 to 30 μm and a length of about 100 μm. The pulse laser beam that has passed through the slit is incident on the amorphous silicon film through an imaging optical system that images the slit on the surface of the amorphous silicon thin film. The magnification of this imaging optical system is, for example, 1/3. At this time, the width of the irradiated region of the laser beam on the surface of the amorphous silicon film is about 1 to 10 μm and the length is about 33 μm. The beam intensity distribution in the width direction of the irradiated region is close to a rectangle.
When the laser beam is incident on the amorphous silicon film, the amorphous silicon is melted. Since the cooling rate in the vicinity of the edge of the melted region is faster than the internal cooling rate, solidification starts from the vicinity of the edge. The solidified portion becomes a nucleus, and crystals grow from the nucleus toward the inside of the molten portion. Since crystal growth starts from the two longer edges of the irradiated region, a grain boundary of crystal grains grown from both sides is formed at substantially the center in the width direction of the irradiated region.
The irradiation region of the pulse laser beam is moved in the width direction by about 50% of the width, and the second pulse laser beam is incident. A region on one side of the grain boundary formed at substantially the center of the irradiated region during the first pulse laser beam irradiation is remelted. The crystal grains in the region not remelted become seed crystals, and the crystal grows in the remelted region.
By repeating the laser irradiation while moving the irradiation region of the pulse laser beam, the crystal can be grown in the moving direction of the irradiation region.
In the following Patent Documents 1 to 3, a technique is disclosed in which the second harmonic of an Nd: YAG laser is used, the beam cross section is shaped into a linear shape, the amorphous silicon layer is irradiated, and a crystal is grown in the lateral direction. Yes. Patent Documents 4 and 5 disclose techniques for growing crystals in the lateral direction by using an excimer laser and irradiating an amorphous silicon layer through a patterned mask.
JP 2000-260731 A JP 2000-286195 A JP 2000-28621 A Special Table 2000-505241 JP 2001-274088 A

  A technique for forming larger crystal grains is desired. An object of the present invention is to provide a new technique for growing crystals laterally.

According to one aspect of the invention,
(A) preparing a workpiece on which a thin film made of an amorphous material is formed on the surface;
(B) A pulse laser beam having a beam cross section that is long in one direction on the surface of the thin film is incident on the thin film, and the thin film is melted and then solidified, and an edge and a center extending in the major axis direction of the beam incident region In the region between the lines, a crystal grain connected in the major axis direction is generated in a first band-shaped region that is separated from the edge and the center line by a certain distance and extends in the major axis direction. Process,
(C) The incident position of the pulse laser beam moves in the minor axis direction of the beam incident region, and the crystal grains generated in the first band-shaped region are not completely melted, and the thin film in the region in contact with the crystal grains Provides a method of manufacturing a polycrystalline film, which includes a step of making a pulse laser beam enter under melting conditions and using the crystal grains as seed crystals to grow crystals on both sides of the band-like region.

According to another aspect of the invention,
(I) preparing a workpiece on which a thin film made of an amorphous material is formed on the surface;
(J) A step in which a pulse laser beam having a beam cross section that is long in one direction on the surface of the thin film is incident on the thin film, and the thin film is melted and then solidified to be polycrystallized. In the first band-shaped region defined by the imaginary line separated from the edge extending in the axial direction by a distance inward and the center line of the beam incident region, the crystal grains continuous in the major axis direction are formed. The pulse laser beam is generated under the condition that the crystal grains generated in the first band region on one side of the center line and the crystal grains generated in the other first band region are in contact with each other. An incident step,
There is provided a method for producing a polycrystalline film, wherein a gradient in a minor axis direction of a pulse energy density of a pulse laser beam is 280 mJ / cm ² / μm or less at an outer edge extending in a major axis direction of the first band-shaped region. Provided.

  Large crystal grains can be formed by irradiation with a pulsed laser beam under the above conditions.

  FIG. 1 shows a schematic diagram of a laser annealing apparatus used in an embodiment of the present invention. The laser annealing apparatus includes a processing chamber 40, a transfer chamber 82, carry-in / out chambers 83 and 84, a laser light source 71, a homogenizer 72, a CCD camera 88, and a video monitor 89. A linear motion mechanism 60 including a bellows 67, coupling members 63 and 65, a linear guide mechanism 64, a linear motor 66, and the like is attached to the processing chamber 40. The linear motion mechanism 60 can translate the stage 44 disposed in the processing chamber 60.

  The processing chamber 40 and the transfer chamber 82 are connected via a gate valve 85, and the transfer chamber 82 and the carry-in / out chamber 83, and the transfer chamber 82 and the carry-in / out chamber 84 are connected via gate valves 86 and 87, respectively. . Vacuum pumps 91, 92, and 93 are attached to the processing chamber 40 and the loading / unloading chambers 83 and 84, respectively, so that the inside of each chamber can be evacuated.

  A transfer robot 94 is accommodated in the transfer chamber 82. The transfer robot 94 transfers the processing substrate between the processing chamber 40 and the loading / unloading chambers 83 and 84.

  A quartz window 38 for transmitting a laser beam is provided on the upper surface of the processing chamber 40. Note that visible optical glass such as BK7 may be used instead of quartz. The pulsed laser beam output from the laser light source 71 enters the homogenizer 72 through the attenuator 76. The homogenizer 72 makes the cross-sectional shape of the laser beam elongated and makes the strength in the major axis direction uniform. The laser beam that has passed through the homogenizer 72 passes through an elongated quartz window 38 corresponding to the cross-sectional shape of the beam, and is incident on a processing substrate held on a stage 44 in the processing chamber 40. The relative position of the homogenizer 72 and the processing substrate is adjusted so that the surface of the substrate coincides with the homogenized surface.

  The direction in which the stage 44 is translated by the linear motion mechanism 60 is a direction orthogonal to the longitudinal direction of the quartz window 38. As a result, a wide area on the substrate surface can be irradiated with a laser beam, and the amorphous semiconductor film formed on the surface of the substrate can be polycrystallized. The substrate surface is photographed by a CCD camera 88, and the substrate surface being processed can be observed by a video monitor 89.

  A method for manufacturing a polycrystalline film according to the first embodiment will be described with reference to FIGS.

  FIG. 2A shows a cross-sectional view of the workpiece 1 and an example of a pulse energy density distribution in the minor axis direction of the laser beam on the surface of the workpiece 1. A workpiece 1 has a three-layer structure including a glass substrate 2 having a thickness of 0.7 mm, a silicon oxide film 3 having a thickness of 100 nm covering the surface, and an amorphous silicon film 4 having a thickness of 50 nm formed on the surface. Have The silicon oxide film 3 is formed by, for example, chemical vapor deposition (CVD) or sputtering. The amorphous silicon film 4 is formed by, for example, low pressure CVD (LP-CVD) or plasma enhanced CVD (PE-CVD).

  The pulse energy density distribution 5 in the minor axis direction of the beam cross section can be approximated by a Gaussian distribution. The amorphous silicon film 4 in the region 6 where the laser beam having the pulse energy density equal to or higher than the threshold Eth for completely melting the amorphous silicon is incident is completely melted. Here, “completely” means that the silicon film is melted over the entire thickness.

  In the region 12 outside the range where the pulse energy density is between the threshold values Eth and Ec, the silicon film is partially melted. Here, “partially” means that a part of the silicon film is melted, but a part that remains in an amorphous state and does not melt remains. The amorphous silicon film 4 in the region 9 outside the position where the pulse energy density becomes Ec is not melted. When the molten silicon solidifies, silicon crystal grains are formed.

  The inventor of the present application forms relatively large crystal grains in the band-like region 7 in the vicinity of the position where the pulse energy density becomes the threshold value Eth, and forms small microcrystal grains in the region 8 inside thereof. In the region 12, it has been found that crystal grains having a size intermediate between the size of the crystal grains in the region 8 and the size of the crystal grains in the band-like region 7 are randomly distributed. Here, “size of crystal grains” means the average size of crystal grains distributed in the region.

  FIG. 2B shows a schematic plan view of the region irradiated with the pulse laser beam. The vertical direction in FIG. 2B corresponds to the long axis direction of the beam incident region. A band-like region 7 extending in the major axis direction is disposed between the edge 10 extending in the major axis direction of the beam incident region and the center line 11. The band-like region 7 is arranged at a certain distance from the edge 10 of the beam incident region. A large number of crystal grains 13 connected in the major axis direction are formed in the band-like region 7.

  The intensity distribution in the short axis direction of the pulse laser beam is approximated by a Gaussian distribution. The half value width of the intensity distribution in the minor axis direction is referred to as a beam width. Actually, the beam component at the base of the Gaussian distribution is irradiated on both sides of the region corresponding to the beam width on the surface of the workpiece. The edge 10 of the beam incident region can be defined as, for example, a portion that is 10% of the maximum value of the pulse energy density.

  FIG. 3 shows a sketch of a scanning electron micrograph (SEM photograph) of a polycrystallized silicon film. The incident pulse laser beam is the second harmonic (wavelength 527 nm or 524 nm) of the Nd: YLF laser, and the pulse width is 100 ns. The length in the major axis direction of the beam cross section on the surface of the workpiece is 5 mm, and the beam width is 0.2 mm.

Two pulsed laser beams having a pulse energy density of 500 mJ / cm ^{2 on} the surface of the object to be processed were simultaneously irradiated to the same location. For this reason, the effective pulse energy density is 1 J / cm ² . The pulse energy density was calculated by dividing the pulse energy by the area of the beam cross section on the surface of the workpiece.

  It can be seen that relatively large crystal grains are formed in the band-like region 7 and are continuous in the major axis direction. These crystal grains have a length in the minor axis direction of about 1.5 to 2 μm and a size in the major axis direction of about 0.7 to 1.5 μm. A large number of fine crystal grains are formed in the region 8 between the two belt-like regions 7.

  In addition, it can be seen that in the region 12 outside the band-like region 7, crystal grains that are larger than the fine crystal grains in the region 8 and smaller than the crystal grains in the band-like region 7 are randomly arranged. The region 9 outside the random distribution region 12 remains in an amorphous state. By observing with a microscope, the boundary between these regions can be detected as a color difference.

Next, a mechanism for generating crystal grains of various sizes as shown in FIG. 3 will be considered.
FIG. 4A shows the temperature dependence of the growth rate of silicon crystal, and FIG. 4B shows the temperature dependence of the nucleation rate of crystal growth. The vertical axis of FIG. 4A represents the growth rate in the unit “m / s”, the vertical axis of FIG. 4B represents the nucleation rate in the unit “1 / cm ³ · s”, and the horizontal axis of both represents the temperature. Represented by “K”. The graphs of FIGS. 4A and 4B were published in the material collection No. 22 pages 27-32 of the 21st FEM seminar of the Japan Society for Technology of Plasticity Simulation Integrated System on July 14, 1999. It was obtained from the technique of “Micro analysis of dynamic crystal growth process of polycrystals” by Daiichi Ichijima (Sumitomo Heavy Industries, Ltd.).

  As shown in FIG. 4A, the growth rate is 0 at the melting point (1683K) of single crystal silicon, and the growth rate increases as the temperature decreases. In the vicinity of a temperature of 1500 K, the growth rate shows a maximum value. Therefore, the lower the temperature of the molten silicon, the faster the growth rate. The growth rate also depends on the temperature gradient at the interface between the solid phase portion and the liquid phase portion. If the temperature gradient is steep, the growth rate is fast.

As shown in FIG. 4B, the nucleation rate increases as the temperature decreases from the melting point of silicon, and shows a maximum value near a temperature of 600K.
The band-like region 7 shown in FIG. 3 is considered to be a region having a suitable temperature gradient with a low nucleation rate and a high growth rate and a suitable temperature gradient at the solid-liquid interface. The region 12 between the band-like region 7 and the amorphous region 9 has a higher nucleation rate because the temperature is lower than that of the band-like region 7, and a growth rate is slow because the temperature gradient at the solid-liquid interface is gentle. it is conceivable that. In this region, it is considered that many nuclei were generated before growing into a large crystal, so that the crystal grain could not be enlarged.

  In the microcrystalline region 8, nuclei are explosively generated due to a decrease in temperature, and it is considered that the nucleation was dominant over the growth rate. When cooled to a temperature at which the nucleation rate increases rapidly, crystal growth in the band-like region 7 is hindered by newly generated nuclei, and crystal growth stops. It is considered that the place where the crystal growth stopped corresponds to the boundary between the band-like region 7 and the microcrystalline region 8.

  More specifically, in the region 12, crystal growth (heterogeneous growth) from the nucleus generated at the interface between the molten layer and the underlying layer becomes dominant, and in the microcrystalline region 8, the molten layer It is thought that crystal growth (homogeneous growth) from nuclei generated inside becomes dominant. It is considered that a large crystal grain is formed at the boundary between a region where heterogeneous growth is dominant and a region where homogeneous growth is dominant.

  In order to form large crystal grains, it is necessary that the molten portion of silicon has a suitable temperature gradient and temperature with a high growth rate and a low nucleation rate. When the temperature gradient at the position of the band-like region 7 shown in FIG. 2A is steep, the region maintained at a suitable temperature becomes narrow, and large crystal grains are hardly formed. In order to form large crystal grains, it is preferable to make the gradient of the pulse energy density distribution in the vicinity of the band-like region 7 gentle.

  If the gradient of the pulse energy density distribution is made too steep, the nucleus generation rate increases. On the other hand, if the gradient of the pulse energy density distribution is made too gentle, the growth rate becomes slow. Therefore, it is considered that there is a suitable range in which the gradient of the pulse energy density distribution is not too steep and not too gentle to achieve a suitable temperature and a solid-liquid interface temperature gradient with a high growth rate and low nucleation rate. .

Next, a preferable shape of the pulse energy density distribution will be described with reference to FIG.
FIG. 5A shows the relationship between the crystal grain size and the beam width on the surface of the workpiece. The horizontal axis represents the beam width in the unit “μm”, and the vertical axis represents the crystal grain size in the unit “μm”. The size of the crystal grains was calculated using a crystal growth evaluation program disclosed in Japanese Patent Application Laid-Open No. 2001-297993.

  The object to be processed is a silicon oxide film having a thickness of 100 nm and an amorphous silicon film having a thickness of 50 nm formed thereon. The wavelength of the pulse laser beam is 527 nm, the pulse width (half-value width) is 140 ns, and the width of the beam incident region is 1 μm outside the position where the pulse energy density is half the peak value and 5 μm inside. A simulation was performed for a region having a total width of 6 μm. This is because the gradient of the pulse energy density distribution is almost maximum at a position where the value is half the peak value, and large crystal grains are formed in this region.

The intensity distribution in the minor axis direction of the beam incident region was a Gaussian distribution. For each of the four cases where the width of the beam cross section is 5.0 μm, 8.3 μm, 16.7 μm, and 83.0 μm, simulation was performed at various peak intensities, and under the conditions that the maximum crystal grain was obtained. The size of the crystal grain was the size of the crystal grain at the beam width. When the width of the beam cross section is 5.0 μm, 8.3 μm, 16.7 μm, and 83.0 μm, the maximum value of the pulse energy density is 1100 mJ / cm ² , 1400 mJ / cm ² , 1500 mJ / cm ² , and 1500 mJ, respectively. The largest crystal grain was obtained under the condition of / cm ² .

  FIG. 5B shows the relationship between the gradient of the pulse energy density distribution at a position showing a half value of the peak intensity and the size of the crystal grains. For each evaluation point in FIG. 5A, the gradient of the pulse energy density distribution was calculated, and the graph in FIG. 5B was created.

As shown in FIG. 5B, the crystal grains gradually increase as the gradient of the pulse energy density distribution increases from 20 mJ / cm ² / μm. This is presumably because the crystal growth rate increases. However, when the gradient of the pulse energy density distribution is around 170 mJ / cm ² / μm, the size of the crystal grain shows the maximum value, and when the gradient is made larger than that, the crystal grain becomes smaller. This is presumably because the gradient of the pulse energy density becomes steep, the temperature gradient at the solid-liquid interface also becomes steep, and the cooling rate increases due to thermal diffusion in the lateral direction. That is, it is considered that a sufficient crystal growth time is not secured and a large number of nuclei are generated before the crystal grows greatly.

When the polycrystalline film shown in FIG. 3 was produced, the gradient at a position where the pulse energy density was 500 mJ / cm ² was 13 mJ / cm ² / μm. The size in the short axis direction of the crystal grains in the band-like region 7 shown in FIG. 3 is about 1.5 to 2 μm, which is almost the same as the tendency of the simulation result shown in FIG. 5B. Even when the gradient was set to 18 mJ / cm ² / μm, the same tendency as the simulation result shown in FIG. 5B was obtained. If the gradient at the position where the pulse energy density is 500 mJ / cm ² is 10 mJ / cm ² / μm or more, a tendency similar to the simulation result shown in FIG. 5B will be obtained.

Judging from the simulation result shown in FIG. 5B, in order to form a large crystal grain, a pulse at the position of the band-like region 7 shown in FIGS. 2A and 2B (more strictly, the outer edge of the band-like region 7). The gradient of the energy density distribution is preferably 280 mJ / cm ² / μm or less. The gradient is preferably 10 mJ / cm ² / μm or more. When the same simulation was performed with the amorphous silicon film having a thickness of 100 nm, a tendency similar to that obtained when the thickness was 50 nm was obtained.

  Further, in the first embodiment, as shown in FIG. 2B, a portion having a relatively high intensity at the base of the laser beam is incident on the region 12 where the crystal grains are randomly distributed. By irradiating the region 12 with a laser beam having a relatively high intensity, the temperature of this region rises. For this reason, the temperature of the band-like region 7 and the temperature gradient at the solid-liquid interface satisfy a suitable condition for forming large crystal grains. In order to obtain a sufficient effect of increasing crystal grains, the width W of the region 12 is preferably set to 15 μm or more.

Next, the relationship between the pulse width and the crystal grain size will be described with reference to FIG.
FIG. 6 shows the relationship between crystal grain size and pulse width. The horizontal axis represents the pulse width in the unit “ns”, and the vertical axis represents the crystal grain size in the unit “μm”. The size of the crystal grains was calculated using the above-described crystal growth evaluation program.

  The processing object and the wavelength of the pulse laser beam are the same as the conditions described in FIG. In addition, the beam width on the surface of the object to be processed was 16.7 μm. The simulation method is the same as the method described in FIG.

  It can be seen that when the pulse width is increased, the formed crystal grains become larger. This is presumably because the temperature drop gradually decreases as the pulse width becomes longer, and as a result, the time during which the melted portion is maintained at a suitable temperature becomes longer. However, if the pulse width is increased under the condition where the pulse energy is constant, the peak intensity of the pulse laser beam is lowered, and a sufficient power density cannot be maintained. Therefore, the upper limit of the pulse width is limited by the output characteristics of the laser light source used.

  When an excimer laser is used as the laser light source, the pulse width is generally 70 ns or less. In general, all solid-state lasers such as Nd: YLF lasers have pulse widths of 20 to 30 ns and those of 100 ns or more. In order to form larger crystal grains, it is preferable to use those having a pulse width of 100 ns or more.

  As described above, in order to optimize the temperature state of the silicon melted part, the consideration was made by paying attention to the shape and pulse width of the pulse energy density distribution, but before the melted part is completely solidified after the incidence of the pulse laser beam. The temperature state can also be controlled by re-injecting the pulse laser beam at the same position.

FIG. 7 shows an example of the waveform of a laser beam incident on the workpiece. The horizontal axis represents the elapsed time, and the vertical axis represents the intensity of the laser beam. Time t ₁ 1 shot of the pulsed laser beam S1 is incident on, the second shot of the pulsed laser beam S2 to the time t ₂ is incident. The pulse widths (half widths) of the first and second shot pulse laser beams are PW1 and PW2, respectively. Although FIG. 7 shows the case where the peak intensity of the pulse laser beam of the second shot is smaller than the peak intensity of the pulse laser beam of the first shot, both may be the same.

  The amorphous silicon film is melted by the incidence of the first-shot pulse laser beam S1 shown in FIG. As the temperature decreases, nuclei are generated and crystals grow from the nuclei. Before cooling to a temperature at which the nucleation rate increases, the pulse laser beam S2 of the second shot is incident and reheated. Thereby, nucleation can be suppressed and crystal growth can be continued. For this reason, it is possible to form large crystal grains.

  For example, the pulse laser beam S2 for the second shot may be incident before the portion melted by the first shot is completely solidified. For example, the delay time from the first shot laser beam incidence to the second shot laser beam incidence may be about 300 to 1500 ns. When an all-solid-state laser is used as the laser light source, the delay time can be easily controlled compared to the case where an excimer laser is used. In addition, as will be described later, once formed crystal grains are less likely to melt than a portion in an amorphous state. For this reason, once formed crystal grains are difficult to be remelted by irradiation with the pulse laser beam S2 of the second shot.

For example, the crystal grain size was about 2.1 μm when a pulse laser beam having a peak value of pulse energy density of 1300 mJ / cm ² , a pulse width of 140 ns, and a beam width of 16.7 μm was incident. In contrast, the peak value of the first shot of pulse energy density 1300 mJ / ^cm 2, 2 shot peak value 700 mJ / cm ² pulse energy density was subjected to a multi-crystallized with the conditions of the delay time 900 ns, grain The size of was about 4.4 μm. In this way, the crystal grains can be enlarged by providing a two-shot pulse laser beam with a delay time.

  A method of irradiating the pulse laser beam of the second shot before the melted portion is solidified by the incidence of the first shot is called a double pulse method. More generally, a method of irradiating a pulse laser beam of two or more shots before the molten silicon is solidified is called a multi-pulse method.

  In the method according to the first embodiment, a mask for making the intensity distribution of the laser beam top-flat is not used. For this reason, the energy utilization efficiency of a laser beam can be improved.

  In addition, by the method of the first embodiment, it is possible to form crystal grain rows in which crystal grains are arranged in a row in the first direction. The average size of crystal grains in the direction orthogonal to the first direction can be 1.5 μm or more.

Next, a second embodiment in which the crystal grains formed by the method according to the first embodiment are further expanded in the in-plane direction of the substrate will be described.
FIG. 8 schematically shows the state of crystal growth. Each of FIGS. 8A to 8G represents a cross section of the silicon film, and the horizontal direction of the figure corresponds to the short axis direction of the incident region of the pulse laser beam.

  As shown in FIG. 8A, when the pulse laser beam is incident by the method according to the first embodiment, a large number of continuous stripes in the major axis direction (direction perpendicular to the paper surface of FIG. 8) are located at the positions of the two strip regions 7. Crystal grains are formed. In the region 8 sandwiched between the two belt-like regions 7, fine crystal grains are formed. The width of each band-like region 7 is 4 μm, for example. As shown in FIGS. 5A and 5B, it is sufficiently possible to form crystal grains with a size of about 4 μm by optimizing the laser beam incidence conditions.

  FIG. 8B shows the crystallization state after the second irradiation by moving the incident position of the laser beam by 15 μm in the minor axis direction. For example, when the beam width is 100 μm and the moving distance is 15 μm, the overlap rate is 85%.

  A band-shaped region 20 in which crystal grains are continuous is formed at a position where the band-shaped region 7 is moved by 15 μm in the moving direction. The width of the band-like region 20 is 4 μm. The amorphous silicon film, fine crystal grains, and small crystal grains in the region sandwiched between the two strip regions 20 are melted, but as will be described later, the large crystal grains in the strip region 7 are difficult to melt. Actually, the crystal grains in the band-like region 7 are partially melted, but a part remains as crystals. As the temperature decreases, the crystal grains remaining in the band-like region 7 become seed crystals and crystal growth occurs.

  Assuming that crystal growth similar to the size of the crystal grains generated by the first irradiation occurs, the length of the crystal growing on both sides of the band-like region 7 is about 4 μm. For this reason, a polycrystalline region 7a having a width of about 12 μm is formed around the band-like region 7 located on the front side in the moving direction. The width of the microcrystalline region 15 between the strip region 7a and the strip region 20 located on the front side in the moving direction is about 7 μm. Since the amorphous silicon film, fine crystal grains, and small crystal grains around the band-like region 7 located on the rear side in the movement direction are not melted, crystal growth does not occur.

FIG. 8C shows the crystallization state after the third irradiation by moving the incident position of the laser beam further 15 μm in the minor axis direction.
A band-like region 21 in which crystal grains are continuous is formed at a position where the band-like region 20 is moved by 15 μm in the moving direction. The width of the strip region 21 is 4 μm. Furthermore, crystal growth occurs using the crystal grains in the band-like region 7a and the band-like region 20 located on the front side in the moving direction as seed crystals.

  A crystal of about 4 μm grows from the band-like region 7a toward the rear side in the moving direction. At the same time, a crystal of about 4 μm grows from the band-like region 20 toward the front side in the moving direction. In the region 15 sandwiched between the strip region 7a and the strip region 20, crystal growth occurs from both sides toward the center. Since the width of the region 15 is about 7 μm, the crystal grains collide with each other and the crystal growth stops when the region 15 grows by 3.5 μm from both sides.

  As a result, a band-like region 7b having a width of 19.5 μm including the band-like region 7a is formed, and a band-like region 20a having a width of 11.5 μm including the band-like region 20 is formed. A large number of crystal grains connected in the major axis direction are formed in the band-like regions 7b and 20a. Grain boundaries are arranged along the center line 16 of the region 15. Since crystal grains collide with each other, a mountain-shaped convex portion is formed at the position of the center line 16.

FIG. 8D shows the crystallization state after the fourth irradiation by moving the incident position of the laser beam further by 15 μm in the minor axis direction.
A belt-like region 22 is formed at a position where the belt-like region 21 is moved forward by 15 μm in the moving direction. A crystal grows on the front side in the moving direction using the crystal grains in the band-shaped region 20a as a seed crystal, and a crystal grows on both sides using the crystal grains in the band-shaped region 21 as a seed crystal. As a result, a strip-shaped region 20b having a width of 15 μm and a strip-shaped region 21a having a width of 11.5 μm are formed.

FIG. 8E to FIG. 8G show the crystallization state after the irradiation position of the laser beam is moved by 15 μm in the minor axis direction and the 5th to 7th irradiations are performed.
By the fifth irradiation, a new band-like region 23 is generated, and at the same time, the band-like regions 21a and 22 are spread to form the band-like regions 21b and 22a. By the sixth irradiation, the band-like regions 22a and 23 are spread, and the band-like regions 22b and 23a are formed. By the seventh irradiation, the band-like region 23a is expanded and the band-like region 23b is formed.

  As described above, by repeating irradiation while moving the incident position of the laser beam in the minor axis direction, almost the entire surface of the amorphous silicon film can be polycrystallized.

  FIG. 9 shows a sketch of an SEM photograph of a polycrystalline film produced by the method shown in FIG. A plurality of band-like regions 25 are observed. Each band 25 has a width of about 15 μm, and a large number of crystal grains connected in the major axis direction are formed in the band 25. Mountain-shaped projections 26 are formed at the boundaries between the strip-like regions 25 adjacent to each other.

  Next, conditions for polycrystallizing the entire surface will be described with reference to FIG. When the overlap rate when moving the incident position of the pulse laser beam is reduced, the width of the microcrystalline region 15 shown in FIG. 8C is expanded, and before the crystal grains growing from both sides of the region 15 collide with each other, the laser beam The incident region is deviated from the region 15. Even if the overlap rate is kept constant, the same phenomenon occurs when the length of crystal growth per irradiation is shortened. For this reason, when the length of crystal growth per irradiation is short, the overlap rate must be increased.

  FIG. 10 shows the relationship between the length of crystal growth per irradiation and the required overlap rate. The horizontal axis represents the length of crystal growth per irradiation in the unit “μm”, and the vertical axis represents the overlap rate in the unit “%”. For example, when the length of crystal growth per irradiation is 10 μm, the overlap rate may be 70% or more. It can be seen that when the length of crystal growth per irradiation is shortened, the overlap ratio required for polycrystallizing the entire surface is increased.

  In order to polycrystallize the entire surface, the center line 16 of the microcrystalline region 15 becomes a silicon melting region by laser beam irradiation until crystal grains growing from both sides of the microcrystalline region 15 shown in FIG. 8B collide with each other. What is necessary is just to set an overlap rate so that it may fall within.

Next, a preferable wavelength of the laser beam when the amorphous silicon film is polycrystallized will be described with reference to FIG.
FIG. 11 shows the wavelength dependence of the light absorption coefficient of amorphous silicon and single crystal silicon. The horizontal axis represents the wavelength in the unit “nm”, and the vertical axis represents the absorption coefficient in the unit “× 10 ⁷ cm ⁻¹ ”. Black circles and white circles in the figure indicate the absorption coefficient of single crystal silicon and the absorption coefficient of amorphous silicon, respectively.

  It can be seen that the absorption coefficient of amorphous silicon is larger than that of single crystal silicon in a wavelength region of about 340 nm or more. In particular, in the wavelength range of 400 nm to 600 nm, the absorption coefficient of amorphous silicon is one digit or more larger than that of single crystal silicon. When crystal growth is performed using once formed crystal grains as seed crystals, it is preferable to melt the amorphous region without melting the crystal grains. The region in which the actually formed crystal grains are distributed is not a single crystal but a polycrystal. The absorption coefficient of polycrystalline silicon depends on the size of crystal grains, and is an intermediate absorption coefficient between single crystal and amorphous. When the crystal grain becomes large, it approaches the absorption coefficient of the single crystal, and when the crystal grain becomes small, it approaches the absorption coefficient of amorphous.

  Therefore, in order to preferentially melt the amorphous region 9, the random distribution region 12, and the microcrystalline region 8 without melting large crystal grains in the band-like region 7 shown in FIG. 2B, a pulse laser having a wavelength of 340 nm or more is used. It is preferable to use a beam. If the wavelength becomes too long, the absorption coefficient decreases, so the wavelength of the pulse laser beam to be used is preferably 900 nm or less.

  In the excimer laser wavelength region (approximately 308 nm), the absorption coefficient of amorphous silicon is higher than the absorption coefficient at wavelengths of 340 to 900 nm. For this reason, absorption occurs only in the vicinity of the surface of the amorphous silicon film, and a temperature gradient occurs in the thickness direction. On the other hand, when a laser beam having a wavelength of 340 to 900 nm is used, the laser beam penetrates to a relatively deep region of the amorphous silicon film and is heated almost uniformly in the thickness direction. For this reason, a higher quality crystal can be formed.

Next, with reference to FIG. 12, the manufacturing method of the polycrystalline film by the 3rd Example is demonstrated.
FIG. 12A shows the relationship between the pulse energy density distribution in the minor axis direction of the irradiated laser beam and the region to be polycrystallized. Microcrystals are formed in the region 35 where the portion having the highest pulse energy density is incident, and strip regions 30A and 30B in which large crystal grains are continuous in the major axis direction are formed on both sides thereof. The beam width is set so that the width of the region 35 where the microcrystal grains are formed is approximately equal to the width of each of the strip-like regions 30A and 30B.

The second laser irradiation is performed by moving the incident position of the laser beam in the minor axis direction by a distance equal to the width of the band-like region 30A.
As shown in FIG. 12B, a band-shaped region 31A in which large crystal grains are continuous is formed between the band-shaped regions 30A and 30B in which crystal grains are already formed. At the same time, a belt-like region 31B is formed on the front side of the belt-like region 30B located on the front side in the moving direction.

In this way, four belt-like regions 30A, 31A, 30B, and 31B are formed by two irradiations. Crystal grains in the band-like regions adjacent to each other are in contact with each other. By repeating the same process, the entire surface can be polycrystallized.
Depending on the temperature condition, the crystal growth may not be performed from the nuclei generated in the region 35 shown in FIG. 12A, but the crystal grains in the band-like regions 30A and 30B on both sides may be used as seed crystals. It may happen.

Next, with reference to FIG. 13, the manufacturing method of the polycrystalline film by the 4th Example is demonstrated.
FIG. 13A shows the relationship between the pulse energy density distribution in the minor axis direction of the laser beam to be irradiated and the polycrystallized region. On both sides of the position corresponding to the maximum value of the pulse energy density, band-like regions 36A and 36B in which large crystal grains are continuous in the major axis direction are formed. Since the beam width is narrow, the crystal grains generated from the nuclei in the band-shaped region 36A and the crystal grains generated from the nuclei in the band-shaped region 36B are in contact with each other. A grain boundary is arranged along the line 38 in which both are in contact.

The incident position of the laser beam is moved in the minor axis direction by the total width of the strip regions 36A and 36B, and the second irradiation is performed.
As shown in FIG. 13B, strip-shaped regions 37A and 37B that are in contact with each other are formed. The band-like region 37A located on the rear side in the movement direction is in contact with the band-like region 36B located on the front side in the movement direction formed by the first irradiation. By repeating the same process, the entire surface can be polycrystallized.

  Large crystal grains can be formed by setting the pulse energy density distribution of the pulse laser beam irradiated in the third and fourth embodiments to the preferred shape described in the first embodiment. Further, as shown in FIG. 7, the crystal grains can be made larger by making a two-shot pulse laser beam incident on the same position.

Next, with reference to FIGS. 14-15C, the manufacturing method of the polycrystalline film by 5th Example is demonstrated.
FIG. 14 shows an example of a cross-sectional view of the workpiece 1 near the laser beam incident position and an example of a pulse energy density distribution in the minor axis direction of the beam cross section. In general, the pulse energy density is obtained by dividing the pulse energy by the area of the beam cross section. Strictly speaking, the pulse energy density obtained by this calculation is an average value in the beam cross section. Since the light intensity in the beam cross section is not constant, the pulse energy density is also not constant. When the light intensity distribution is approximated by a Gaussian distribution, the pulse energy density distribution is also approximated by a Gaussian distribution.

  As shown in FIG. 14, the object to be processed is formed by laminating a silicon oxide film 3 and an amorphous silicon film 4 on a glass substrate 2 as in the case of the first embodiment described with reference to FIG. 2A. Laminated substrate. The incident position of the pulse laser beam moves to the right in FIG.

  A part of the laser beam that has passed through the homogenizer 72 shown in FIG. 1 is shielded by the light shielding plate 18 and enters the amorphous silicon film 4 via the imaging optical device 19. The light shielding plate 18 shields light at the base of the pulse energy density distribution in the minor axis direction of the beam cross section. The imaging optical device 19 images the beam cross section at the position where the light shielding plate 18 is disposed on the surface of the amorphous silicon film 4. The imaging magnification is, for example, 1.times.

  When the light shielding plate 18 is not disposed, the pulse energy density distribution in the short axis direction of the pulse laser beam on the surface of the amorphous silicon film 4 is approximated by a Gaussian distribution. That is, the pulse energy density is strong at the center and becomes weaker as it approaches the edge. The distribution of the pulse energy density is not necessarily a Gaussian distribution, and may be a distribution that is generally strong at the center and weaker as it approaches the edge.

Of pulsed laser beam traveling direction of the rear side of the skirt of the incident position of, and the pulse energy density is below the portion E _H is shielded by the light shielding plate 18, in the front, partial pulse energy density is less than E _L Is shaded. The pulse energy density E _L is lower than E _H.

  Actually, the light intensity does not immediately become 0 at the edge of the beam cross section shielded by the light shielding plate 18, and the beam cross section extends to the outside by about 6 μm from the light shielded position. The edge of the beam cross section was set at a position where the light intensity was 20% of the peak value.

A pulse laser beam having such a pulse energy density distribution is incident on the amorphous silicon film 4 for one shot. A region irradiated with a laser beam having a pulse energy density equal to or higher than a threshold value at which the amorphous silicon film 4 is completely melted is melted. When the pulse energy density E _L is equal to or higher than this threshold value, the entire region irradiated with the pulse laser beam is melted. When the molten part is cooled, crystals grow from the edge of the molten part toward the inside.

  As shown in FIG. 15A, a large number of crystal grains 100a arranged in the major axis direction of the beam cross section are formed at the rear edge in the moving direction of the incident position of the pulse laser beam, and a large number of crystal grains are formed at the front edge. 101a is formed. In the region sandwiched between the region where the crystal grain 100a is formed and the region where the crystal grain 101a is formed, fine crystal grains are formed as in the region 8 shown in FIG. The length of the crystal to grow depends on the temperature of the molten part and the temperature gradient at the solid-liquid interface. The temperature and temperature gradient at the rear edge and the temperature and temperature gradient at the front edge are different from each other. For this reason, the lengths of the crystals grown from the edges on both sides of the melted region are different from each other.

  When the temperature and temperature gradient at the rear edge are favorable conditions for crystal growth, the crystal grain 100a formed at the rear edge is larger than the crystal grain 101a formed at the front edge. For example, the lateral dimension of the crystal grain 100a formed at the rear edge could be 7-8 μm.

  Next, the incident position of the pulse laser beam is moved in the minor axis direction of the beam cross section, and the pulse laser beam is incident on one shot. The moving distance of the incident position is a distance at which the rear edge of the beam section of the pulse laser beam to be newly irradiated is in contact with or overlaps the crystal grain 100a. The crystal grains 101a formed at the front edge during the previous irradiation are melted by the current irradiation.

  As shown in FIG. 15B, at the rear edge of the region melted by the current irradiation, the crystal grows in the lateral direction using the crystal grain 100a as a seed crystal, and a large crystal grain 100b including the crystal grain 100a is formed. The When the edge on the rear side of the beam cross section of the pulse laser beam irradiated this time is in contact with the crystal grain 100a, the horizontal dimension of the crystal grain 100b is 14 to 16 μm, which is approximately twice the dimension of the crystal grain 100a.

  The pulse laser beam irradiation is repeated while moving the incident position of the pulse laser beam so that the region irradiated with the previous shot and the region irradiated with the current shot partially overlap. The moving distance is a distance at which the rear edge of the cross section of the pulse laser beam to be newly irradiated is in contact with or overlaps the rear crystal grain formed by the previous irradiation.

  As shown in FIG. 15C, the crystal grains grow in the lateral direction, and large crystal grains 100c are formed. At the time of FIG. 15B, the small crystal grains 101b formed at the front edge of the beam cross section are melted and disappeared by the subsequent irradiation with the pulse laser beam.

  In the fifth embodiment, crystals grow from the rear edge of the beam cross section defined by the light shielding plate 18. In the case of the first embodiment, as shown in FIG. 3, the band-like region 7 where large crystal grains are generated meanders. In the fifth embodiment, since the position where the crystal grains 100a are formed is artificially determined by the light shielding plate 18, the band-like region where the crystal grains 100a are continuous does not meander and has a shape substantially along a straight line. For this reason, at the time of the second irradiation, the rear edge of the beam cross section can be easily positioned so as to be in contact with the band-like region where the crystal grains 100a are continuous.

  The crystal growth direction is also aligned in a direction perpendicular to the long axis of the beam cross section. When an active element is formed in a polycrystalline film, a decrease in carrier mobility caused by a crystal grain boundary can be suppressed by making the current direction of the active element to be formed parallel to the direction of crystal growth. .

  In the above embodiment, the incident position is moved each time a one-shot pulse laser beam is incident. However, as described with reference to FIG. 7, a double pulse that causes a two-shot pulse laser beam to enter the same position. A method may be adopted, or a multi-pulse method may be adopted. Thereby, the crystal grain formed can be enlarged.

A preferable region to be shielded among the skirts of the pulse energy density distribution shown in FIG. 14, that is, the preferred sizes of the pulse energy densities E _H and E _L are obtained by changing the size (width) of the light shielding region. It can be determined by doing.

  Hereinafter, the result of the evaluation experiment actually performed will be described. The laser beam emitted from the laser light source was shaped into a long beam having a beam cross section with a width of 100 μm and a length of 17 mm. Both sides of the beam cross section in the width direction were shielded by a light shielding plate to form a cross section having a width of 22 μm, and this beam cross section was imaged on the surface of the amorphous silicon film. The width of the beam cross section is the half width of the light intensity distribution.

Using two laser light sources, the first shot and the second shot of the pulsed laser beam, a pulse energy density in the amorphous silicon film surface, respectively with 550 mJ / cm ² and 500 mJ / cm ^2, double pulses and 100ns delay time The method was adopted.

  By irradiating the two-shot pulse laser beam under these conditions, the width of the crystal grain 100a formed on the rear side in the scanning direction of the beam cross section became 3.1 μm. By scanning the surface of the amorphous silicon film so that the pulsed laser beam was incident at a pitch of 3 μm, crystals could be continuously grown in the scanning direction as shown in FIG. 15C. When the orientation of each crystal grain was measured, the <110> direction of each crystal grain was aligned in a direction parallel to the crystal growth direction (scanning direction).

Next, with reference to FIGS. 16-17C, the manufacturing method of the polycrystalline film by the 6th Example is demonstrated.
As shown in FIG. 16, in the sixth embodiment, at the front side in the moving direction of the incident position of the pulse laser beam, the skirt portion where the pulse energy density is E _H or less is shielded by the light shielding plate 18, and on the rear side. In addition, the base portion whose pulse energy density is E _L or less is shielded from light by the light shielding plate 18.

As shown in FIG. 17A, when one shot is irradiated, relatively large crystal grains 110a are formed at the front edge of the beam cross section, and relatively small crystal grains 111a are formed at the rear edge.
As shown in FIG. 17B, crystal grains 110b and 111b are formed by moving the incident position of the pulse laser beam and performing the next one-shot irradiation. Since the relatively large crystal grains 110a are difficult to melt, they are hardly melted by the subsequent irradiation. The crystal grains 110b are grown from the front edge of the melted region toward the rear side (crystal grain 110a side). Growth stops when the tip of crystal growth reaches the crystal grain 110a.

  At this time, lateral crystal growth using the crystal grains 110a already formed as seed crystals also occurs. For this reason, the moving pitch of the incident position of the pulse laser beam can be made longer than the width of the crystal grains 110a.

  As shown in FIG. 17C, when irradiation is repeated while moving the incident position of the pulse laser beam, relatively large crystal grains 110a to 110e are formed. In FIG. 17C, relatively small crystal grains 111c are formed at the rear edge of the beam cross section during the third irradiation. In the fourth and subsequent irradiations, the edge on the rear side of the beam cross section is located inside the relatively large crystal grains 110a to 110e, so that no melted portion is generated in the vicinity of the edge on the rear side.

  In the sixth embodiment, as shown in FIG. 17C, for example, a clear boundary is formed between a band-shaped region where crystal grains 110a are continuous and a band-shaped region where crystal grains 110b are continuous. The position of this boundary is artificially determined by the light shielding plate 18. For example, when an active element is formed on a polycrystallized silicon thin film, the boundary of crystal grains can be arranged so that the active element does not straddle the boundary of crystal grains. As described above, it is possible to cover the entire surface of the substrate with a band-shaped region as shown in FIG.

Hereinafter, the result of the evaluation experiment actually performed will be described. The laser beam emitted from the laser light source is shaped into a long beam having a beam cross section with a width of 100 μm and a length of 17 mm. The edge of the beam section on the front side in the scanning direction was shielded by a light shielding plate to form a section shape having a width of 55 μm, and this beam section was imaged on the surface of the amorphous silicon film. Using two laser light sources, the first shot and the second shot of the pulsed laser beam, a pulse energy density in the amorphous silicon film surface, respectively with 710mJ / cm ² and 640 mJ / cm ^2, double pulses and 200ns delay time The method was adopted.

  By irradiating with a two-shot pulse laser beam under these conditions, the width of the crystal grain 110a formed on the front side in the scanning direction of the beam cross section became 5.4 μm. By scanning the surface of the amorphous silicon film so that the pulse laser beam is incident at a pitch of 12 μm, a band-like region having a width of 12 μm in which crystal grains are continuous in the longitudinal direction of the beam cross section was formed. The crystal grains in the band-shaped regions adjacent to each other were in contact with each other at the boundary of the band-shaped regions, and the entire surface could be polycrystallized.

  Although the width of the crystal grain 110a formed by one irradiation is 5.4 μm, the width of the band-like region finally formed becomes 12 μm. The width formed by one irradiation This is because crystal growth in the horizontal direction occurs by subsequent irradiation using 5.4 μm crystal grains as seed crystals. This growth process is the same as the crystal growth process described with reference to FIGS. 8A to 8G.

  In the evaluation experiments of the fifth and sixth examples, the double pulse method was adopted. At this time, it is preferable that the delay time from the incidence of the first shot pulse laser beam to the incidence of the second shot pulse laser beam is 100 to 1000 ns. This suitable delay time is slightly shorter than when no light shielding plate is used. This is because the light intensity distribution has a steep slope on both sides of the beam cross section, and the solidification speed is faster than when no light shielding plate is used.

  Next, a seventh embodiment will be described. In the fifth and sixth embodiments, a part of the laser beam is shielded by the light shielding plate so that the light intensity distribution (or pulse energy density distribution) is asymmetric with respect to the width direction of the beam cross section. It may be shielded from light. When the light intensity distribution is symmetric, crystal grains having substantially the same size are formed on the front edge and the rear edge in the scanning direction. Therefore, the second embodiment described with reference to FIGS. 8A to 8G, the third embodiment described with reference to FIGS. 12A and 12B, or the second embodiment described with reference to FIGS. 13A and 13B. The amorphous silicon film can be polycrystallized by a method similar to the method according to the fourth embodiment.

  In the fifth to seventh embodiments, the beam cross section at the position where the light shielding plate is disposed is imaged on the surface of the amorphous silicon film. However, the light shielding plate may be disposed close to the amorphous silicon film. The distance between the light shielding plate and the amorphous silicon film may be about 0.1 mm, for example.

  In the first and sixth embodiments, a laser beam having an asymmetric light intensity distribution with respect to the width direction of the beam cross section is formed by shielding a part of the laser beam with a light shielding plate. The light intensity distribution may be asymmetric. For example, a gradient filter in which a dot pattern such as chromium (Cr) is arranged on the surface of quartz glass may be arranged in the optical path.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is a schematic plan view of the laser annealing apparatus used in the Example. It is a sectional view of a processing object, and a graph which shows pulse energy density distribution in the processing object surface of a pulse laser beam used in the 1st example. FIG. 3 is a schematic plan view of a polycrystallized workpiece. It is the figure which sketched the SEM photograph of the polycrystalline film produced by the method by a 1st Example. It is a graph which shows the relationship between the temperature of the melted silicon and the crystal growth rate. It is a graph which shows the relationship between temperature and a nucleation rate. It is a graph which shows the relationship between the width | variety of a beam cross section, and the magnitude | size of a crystal grain. It is a graph which shows the relationship between the gradient of a pulse energy density distribution, and the magnitude | size of a crystal grain. It is a graph which shows the relationship between a pulse width and the size of a crystal grain. It is a graph which shows an example of a laser beam waveform in case two shot laser beams are incident on one place. It is the figure which modeled the thin film cross section in the middle of manufacture in the manufacturing method of the polycrystalline film by a 2nd Example. It is the figure which sketched the SEM photograph of the polycrystalline film manufactured by the method by a 2nd Example. It is a graph which shows the relationship between the length of the crystal growth per irradiation, and the overlap rate required in order to polycrystallize the whole surface. It is a graph which shows the wavelength dependence of the absorption coefficient of a single crystal silicon and an amorphous silicon. It is a figure which shows the relationship between the pulse energy density distribution of the pulse laser beam used with the manufacturing method of the polycrystalline film by 3rd Example, and a polycrystallized area | region. It is a schematic plan view of the manufactured polycrystalline film. It is a figure which shows the relationship between the pulse energy density distribution of the pulse laser beam used with the manufacturing method of the polycrystalline film by 4th Example, and a polycrystallized area | region. It is a schematic plan view of the manufactured polycrystalline film. It is sectional drawing of the process target board | substrate and light-shielding plate which are used with the manufacturing method of the polycrystalline film by 5th Example, and the graph which shows distribution of pulse energy density. It is the schematic for showing a mode that it crystallizes with the manufacturing method of the polycrystalline film by 5th Example. It is the schematic for showing a mode that it crystallizes with the manufacturing method of the polycrystalline film by 5th Example. It is the schematic for showing a mode that it crystallizes with the manufacturing method of the polycrystalline film by 5th Example. It is a graph which shows the cross section of the process target board | substrate and light-shielding plate which are used with the manufacturing method of the polycrystalline film by 6th Example, and pulse energy density distribution. It is the schematic for showing a mode that it crystallizes with the manufacturing method of the polycrystalline film by the 6th Example. It is the schematic for showing a mode that it crystallizes with the manufacturing method of the polycrystalline film by the 6th Example. It is the schematic for showing a mode that it crystallizes with the manufacturing method of the polycrystalline film by the 6th Example.

Claims (16)

(A) preparing a workpiece on which a thin film made of an amorphous material is formed on the surface;
(B) A pulse laser beam having a beam cross section that is long in one direction on the surface of the thin film is incident on the thin film, and the thin film is melted and then solidified, and an edge and a center extending in the major axis direction of the beam incident region In the region between the lines, a crystal grain connected in the major axis direction is generated in a first band-shaped region that is separated from the edge and the center line by a certain distance and extends in the major axis direction. Process,
(C) The incident position of the pulse laser beam moves in the minor axis direction of the beam incident region, and the crystal grains generated in the first band-shaped region are not completely melted, and the thin film in the region in contact with the crystal grains Is a method of manufacturing a polycrystalline film, which includes a step of making a pulsed laser beam incident under melting conditions and using the crystal grains as seed crystals to grow crystals on both sides of the band-like region. In the step (c), of the region between the edge on the front side in the moving direction of the incident region of the pulse laser beam and the center line, the region is separated from the edge by a certain distance and is also from the first belt-like region. In the second band-shaped region that is separated by a distance and extends in the major axis direction, crystal grains connected in the major axis direction are generated,
After the step (c),
(D) While moving the incident position of the pulse laser beam in the short axis direction, the pulse laser beam is incident on the thin film, and the crystal grains grown from the first band region toward the second band region; The method for manufacturing a polycrystalline film according to claim 1, further comprising a step of contacting crystal grains grown from the second band-shaped region toward the first band-shaped region.   The method for producing a polycrystalline film according to claim 1, wherein the thin film is formed of silicon, and a wavelength of a pulse laser beam incident on the thin film is 340 to 900 nm. The gradient in the minor axis direction of the pulse energy density of the pulse laser beam irradiated in the step (b) is 280 mJ / cm ² / μm or less at the outer edge extending in the major axis direction of the first band-shaped region. The method for producing a polycrystalline film according to claim 1. The gradient in the minor axis direction of the pulse energy density of the pulse laser beam irradiated in the step (b) is 10 mJ / cm ² / μm or more at the outer edge extending in the major axis direction of the first strip region. The method for producing a polycrystalline film according to claim 4. 6. The process according to claim 1, wherein, in the step (b), after a pulse laser beam is incident on one shot, a delay time of 300 to 1500 ns is provided and the second shot is incident on the same position . A method for producing a polycrystalline film. In the step (b), after one shot of the pulse laser beam is incident, a delay time of 300 to 1500 ns is provided, the second shot is incident at the same position, and the first belt-shaped region is contacted. A random distribution region in which crystal grains smaller than the crystal grains formed in the first band-like region are randomly distributed is formed in a partial region outside the one band-like region. 6. The polycrystalline film according to claim 1 , wherein a pulsed laser beam having a pulse energy density distribution such that an interval from a boundary with the region to the first band-shaped region is 15 μm or more is applied. Manufacturing method. (I) preparing a workpiece on which a thin film made of an amorphous material is formed on the surface;
(J) A step in which a pulse laser beam having a beam cross section that is long in one direction on the surface of the thin film is incident on the thin film, and the thin film is melted and then solidified to be polycrystallized. In the first band-shaped region defined by the imaginary line separated from the edge extending in the axial direction by a distance inward and the center line of the beam incident region, the crystal grains continuous in the major axis direction are formed. The pulse laser beam is generated under the condition that the crystal grains generated in the first band region on one side of the center line and the crystal grains generated in the other first band region are in contact with each other. An incident step,
A method for producing a polycrystalline film, wherein a gradient in a short axis direction of a pulse energy density of a pulse laser beam is 280 mJ / cm ² / μm or less at an outer edge extending in a long axis direction of the first band-shaped region. Slope of the short axis direction of the pulse energy density of the pulsed laser beam, at the outer edge that extends in the axial direction of the first strip region, according to claim 8 is 10mJ ^/ cm 2 / μm or more A method for producing a polycrystalline film. 9. The method for producing a polycrystalline film according to claim 8 , wherein, in the step (j), after the pulse laser beam is incident for one shot, the second shot is incident before the melted portion is completely solidified. After the step (j),
(K) A step of causing the pulse laser beam to be incident on the thin film one after another while moving the incident position of the pulse laser beam in the short axis direction of the beam incident region, melting the thin film, and then solidifying and polycrystallizing. Have
The incidence of the pulse laser beam for one melting and solidification is performed between a virtual line separated from the edge extending in the long axis direction of the beam incident region by an inner distance and a center line of the beam incident region. Crystal grains connected in the major axis direction are generated in the second band-shaped region defined, and the crystal grains generated in the second band-shaped region on one side of the center line and the other second The crystal grains generated in the belt-shaped region are in contact with each other, and the crystal grains generated in the second belt-shaped region on the rear side in the moving direction are the crystal grains already formed on the rear side in the moving direction. The manufacturing method of the polycrystalline film of Claim 8 performed on the conditions to contact. The method for producing a polycrystalline film according to claim 8 , wherein the thin film is made of silicon, and a wavelength of a pulse laser beam incident on the thin film is 340 to 900 nm. In the step (j), a crystal grain smaller than a crystal grain that is in contact with the first belt-like region and is formed in a part of the region outside the first belt-like region in the first belt-like region. A pulse laser beam having a pulse energy density distribution in which a random distribution region is randomly distributed, and a distance from a boundary between the random distribution region and the amorphous region to the first band-shaped region is 15 μm or more. The manufacturing method of the polycrystalline film of Claim 8 irradiated. (A) preparing a workpiece on which a thin film made of an amorphous material is formed on the surface;
(B) The surface of the thin film has a long beam cross section in one direction, and the light intensity distribution in the minor axis direction of the beam cross section is large at the center and becomes smaller as it approaches the edge, and the first shape is asymmetric. Injecting a pulsed laser beam into the thin film for at least one shot;
(C) The incident position of the pulse laser beam moves on the surface of the thin film in a direction intersecting the major axis direction of the beam cross section of the pulse laser beam and partially in the region irradiated with the previous shot. Moving at least one of the incident position of the pulsed laser beam and the workpiece so as to overlap, and
(D) a step of causing a pulse laser beam having a light intensity distribution having the first shape to enter the thin film at least one shot;
(E) a step of alternately repeating the step (c) and the step (d),
In the step (b), the light intensity distribution in the minor axis direction of the beam cross section has a shape with a large central portion and a shape that becomes smaller as it approaches the edge. The following part is shielded from light by the mask, and the other second base part is not shielded from light, or a part of the second base part having a second light intensity lower than the first light intensity is less than the second part. By being shielded from light, the pulse laser beam is obtained,
In the step (b), a crystal grows by a certain length inward from the edge on the first base side of the beam cross section, and a plurality of crystal grains continuous in the longitudinal direction of the beam cross section are formed,
In the step (c), the incident position of the pulse laser beam relatively moves on the thin film so that the second skirt side of the beam cross section is in front of the moving direction, and the moving distance is the same as the previous irradiation. And the crystal grain grown from the first skirt side edge of the beam cross section is a distance where the first skirt side edge of the beam cross section touches or overlaps,
In the step (d), a method for producing a polycrystalline film, wherein a crystal grain grown by the previous irradiation is used as a seed crystal, and the crystal is grown from the seed crystal toward the inside of the beam cross section. (A) preparing a workpiece on which a thin film made of an amorphous material is formed on the surface;
(B) The surface of the thin film has a long beam cross section in one direction, and the light intensity distribution in the minor axis direction of the beam cross section is large at the center and becomes smaller as it approaches the edge, and the first shape is asymmetric. Injecting a pulsed laser beam into the thin film for at least one shot;
(C) The incident position of the pulse laser beam moves on the surface of the thin film in a direction intersecting the major axis direction of the beam cross section of the pulse laser beam and partially in the region irradiated with the previous shot. Moving at least one of the incident position of the pulsed laser beam and the workpiece so as to overlap, and
(D) a step of causing a pulse laser beam having a light intensity distribution having the first shape to enter the thin film at least one shot;
(E) a step of alternately repeating the step (c) and the step (d),
In the step (b), the light intensity distribution in the minor axis direction of the beam cross section has a shape with a large central portion and a shape that becomes smaller as it approaches the edge. The following part is shielded from light by the mask, and the other second base part is not shielded from light, or a part of the second base part having a second light intensity lower than the first light intensity is less than the second part. By being shielded from light, the pulse laser beam is obtained,
In the step (b), a crystal grows by a certain length inward from the edge on the first base side of the beam cross section, and a plurality of crystal grains continuous in the longitudinal direction of the beam cross section are formed,
In the step (c), the incident position of the pulsed laser beam relatively moves on the thin film so that the first base side of the beam cross section is in front of the moving direction,
The pulse energy density of the pulse laser beam irradiated in the step (d) on the surface of the thin film has such a size that the crystal grains formed on the first base side by the previous irradiation are not remelted. A method for producing a polycrystalline film, wherein a crystal grows by a certain length inward from an edge on the first base side of the cross section, and a plurality of crystal grains are formed in the longitudinal direction of the beam cross section. In the step (c), the moving distance of the incident position of the pulse laser beam, the crystal grains grow in the step (d), according to claim 15 which is a distance in contact with the crystal grains formed in the previous irradiation A method for producing a polycrystalline film.