JP2008229701A - Manufacturing method of material having micro rugged surface and electric field radiation type display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric field emission type display whose optical characteristic is improved by forming a micro rugged shape on the surface of a thin film semiconductor used as a fluorescent substance. <P>SOLUTION: The surface of a semiconductor thin film 10 as a workpiece is irradiated with a laser beam 30, and the surface layer of the workpiece is fused and solidified, so that a micro rugged shape 10b is formed on the surface of the workpiece. As a result, photolithography or the like used in the micro fabrication of a semiconductor is not needed at all. Without using all the complicated coating operation and etching operation of a mask and a resist, a micro rugged structure can be directly formed on the surface of the workpiece such as a thin film semiconductor. In the case where an optical material is used as the workpiece, a micro rugged shape such as a width ≤1.5 μm for example can be formed on the surface, the confinement effect of light is weakened, and an effect of improving efficiency of taking out light can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a fine surface uneven shape material that imparts a fine uneven shape to the surface of a work material, and an electrolytic emission display using a phosphor having the fine surface uneven shape.

In a color field emission display (a field emission display (hereinafter referred to as “FED”)) including a full color, a phosphor is used for an anode. In general, a powder phosphor has been used for the phosphor layer of the FED.
In the conventional method for manufacturing a phosphor screen, powder phosphors exhibiting red, blue, and green light emission are respectively arranged at predetermined positions by a photosensitive slurry method. As the powder phosphor, one that has already been heat-treated for the synthesis and activation of the phosphor is used. Therefore, if a phosphor layer is formed on a transparent substrate, the phosphor screen is completed, and light emission is obtained when the phosphor is excited by an electron beam.

In the conventional FED, there is a problem that the phosphor is deteriorated by the collision of the electron beam (deterioration problem), gas emission due to decomposition of the phosphor, and gas emission due to separation of molecules adsorbed on the surface. When charged and discharged, it accelerates to the cathode and flies to the cathode, destroying the cathode structure (outgas problem), charging due to poor electrical conductivity on the surface, and lowering the emission luminance (Charge-up problem). Conventionally, these problems are solved by providing a protective layer made of aluminum on the surface of the powder phosphor layer.
However, in the low-voltage FED, accelerated electrons cannot penetrate deeply, so that a protective layer made of aluminum cannot be used. In addition, the above problems (deterioration problem, outgas problem, charge-up problem, etc.) It is necessary to overcome.
In order to solve the above problems, it has been studied to use a thin film phosphor having a phosphor as a thin film instead of a powder phosphor.

  However, the thin film phosphor is often formed on the substrate as a thin film having extremely high flatness depending on the film forming conditions, and has a plate-like structure. The light emitted from the thin film phosphor does not come out in the direction of the substrate surface because when the incident angle of light with respect to the direction perpendicular to the substrate surface exceeds the critical angle, the light is totally reflected and reflected in the in-plane direction of the phosphor. In addition, because of the high refractive index of the phosphor itself, the critical angle is small and the light that can be extracted is further reduced. For this reason, most of the emitted light is reflected and confined in the in-plane direction of the thin film phosphor, and light cannot be extracted well in the direction of the substrate surface, and the light extraction efficiency is very poor.

  In order to solve the above problems, as a conventional technique, there is a technique for improving the light extraction efficiency by forming a photonic crystal structure on a light emitter or a light extraction surface. In such a technique, a periodic structure is accurately produced on the surface by using a semiconductor processing technique such as photolithography. In particular, it is necessary to use electron beam exposure to produce a structure with high accuracy. The structure produced in this way is called a photonic crystal, and it is possible to extract only light of an arbitrary wavelength from the surface, which is determined by the relationship between the size and period of the structure, and efficiently extract light by controlling the reflection component. It becomes possible.

  One technique for producing a photonic crystal structure is a method of producing a periodic structure with high accuracy using self-organization (Non-Patent Document 1). According to this method, an SOG (Spin On Glass) layer is formed on the surface of a material for which a photonic crystal structure is desired to be formed, and a polymer (when heat is applied) is formed on the surface. A polymer that is phase-separated and agglomerates to a certain size at a certain interval in a self-organizing manner is applied and heated to perform self-organization. Thereafter, plasma etching is performed to remove the polymer while leaving the self-organized tissue, and RIE (RIE: Reactive Ion Etching) is performed to transfer the remaining tissue pattern to the underlying SOG layer. By performing inductively coupled plasma (ICP) etching and argon sputtering for etching the surface to be processed, columnar structures having a diameter of 100 nm and a length of 400 nm are formed at intervals of 150 nm. It has been reported that the nano-concave structure produced in this way allows light to be extracted without reflection when the incident angle of light is within a critical angle, and light that has not been extracted so far above the critical angle can be extracted by the diffraction effect. ing.

Further, as a technique for producing a similar structure, Patent Document 1 discloses that self-organization is performed by applying a polymer having the same characteristics to the surface of a substance for which a photonic crystal structure is desired to be produced, and then heating to self-organize. A fine concavo-convex structure generated by organization or one polymer phase-separated by self-assembly is removed to create a concavo-convex structure. When a material layer serving as a mask having high etching resistance is formed thereon and etching is performed, the portion where the material layer having high etching resistance is thin and a large amount of the polymer layer remains is etched first, and the photonic The material for which the crystal structure is to be fabricated is etched. In addition, a portion with a thick etching resistant material and a thin underlying polymer layer remains during etching to mask a substance for which a photonic crystal structure is to be formed. be able to.
“Toshiba Review Vol.60 No.10”, 2005, p32-35 JP 2003-155365 A

  However, the method of improving the light extraction efficiency by producing the photonic crystal structure on the light emitter or the light extraction surface as described above requires the preparation of a periodic structure with high accuracy. Is costly and the yield is unavoidable. In addition, since a precision processing technique for a semiconductor process is required, a structure cannot be produced at a low cost over a large area.

  In addition, the method of producing a periodic structure with high accuracy using self-organization while producing the structure of a photonic crystal can achieve sufficient light extraction efficiency without creating a precise structure as described above. However, it is difficult to fabricate a structure over a large area at low cost because it is necessary to apply various masks and resists and perform an etching operation, which is not practical.

  The present invention has been made to solve the above-described problems, and a fine surface capable of directly producing a fine structure over a large area by irradiating the surface of a workpiece such as a thin film semiconductor with laser light. It is an object of the present invention to provide a method for manufacturing an uneven material and a field emission display (field emission display) using the thin film semiconductor as an anode thin film phosphor.

  That is, among the manufacturing methods of the fine surface uneven shape material of the present invention, the invention according to claim 1 irradiates the surface of the workpiece with laser light, and melts and solidifies the surface layer of the workpiece. A fine uneven shape is formed on the surface of the workpiece.

  According to a second aspect of the present invention, there is provided a method for producing a fine surface concavo-convex shape material, wherein the fine concavo-convex shape has a size equal to or smaller than a wavelength of laser light.

  The invention of the method for producing a fine surface uneven shape material according to claim 3 is the invention according to claim 1 or 2, wherein the fine uneven shape is one or more of a hemispherical shape, a cylindrical shape or a kamaboko shape. It is characterized in that fine convex shapes are arranged.

  According to a fourth aspect of the present invention, there is provided a method for producing a fine surface irregular shape material according to the third aspect, wherein the kamaboko shape has a length larger than a width.

  According to a fifth aspect of the present invention, there is provided a method for producing a fine surface irregular shape material according to the third or fourth aspect, wherein the fine convex shape has a width of 1.5 μm or less.

  An invention of a method for producing a fine surface irregular shape material according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, the laser beam has a wavelength in an ultraviolet region.

  Invention of the fine surface uneven | corrugated shaped material of Claim 7 is the invention in any one of Claims 1-6, The said to-be-processed material is crystallized by irradiation of a laser beam, It is characterized by the above-mentioned. To do.

  An invention for a method for producing a fine surface irregular shape material according to an eighth aspect is characterized in that, in the invention according to any one of the first to seventh aspects, the workpiece is a thin film semiconductor.

  An invention of a method for producing a fine surface irregular shape material according to claim 9 is characterized in that, in the invention according to any one of claims 1 to 8, the workpiece is a phosphor or a light emitter.

  The invention of the field emission display according to claim 10 is characterized in that the phosphor manufactured according to claim 9 is arranged on the anode side with the fine surface irregularities on the electrolytic emission side.

  That is, according to the present invention, the surface layer of the workpiece is melted by laser light irradiation, and the liquid phase is scattered as droplets due to surface tension in contact with the solid phase below the workpiece, and this is gathered appropriately. Then, a fine uneven shape is formed on the surface by solidifying into a fine convex shape. Also, when the liquid phase covers the entire solid phase by laser light irradiation, a fine uneven shape is formed on the solid surface, so that the solidification speed on the surface of the liquid phase is affected and the fine uneven shape on the surface Is formed.

  In the present invention, physical properties (absorbance with respect to light of each wavelength, surface wettability, vapor pressure, etc.) and laser irradiation conditions (laser wavelength, energy density, laser pulse width, oscillation frequency) By adjusting the number of laser shots, the shape and size of the fine shape and the distribution density can be controlled. Hereinafter, the relationship between various conditions and the shape to be produced will be described.

  First, in the present invention, it is important to melt only the surface of the workpiece to generate a melt, and therefore it is necessary to concentrate the heating region by laser irradiation on the surface. Conditions that greatly affect this include the wavelength of the laser beam to be irradiated and the absorbance of the workpiece to that wavelength. When the absorbance is large, the laser beam is strongly absorbed on the surface of the workpiece, and the laser beam penetration length is shortened. Therefore, it is easy to heat and melt only the workpiece surface and to easily control the shape. Under such conditions, it is possible to control fine irregularities such as a hemispherical structure, a columnar structure, a kamaboko-shaped structure, and a rough surface-shaped structure. If the absorbance is slightly lower, the surface of the workpiece has a larger amount of laser light absorption, but the laser beam penetration length becomes longer, so that not only the surface of the workpiece but also the workpiece is heated deeply. It will be. Then, it becomes difficult to melt only the workpiece surface, resulting in a deep melting depth and a large amount of melt, making it difficult to control the hemispherical structure / cylindrical structure, and the kamaboko-shaped structure / rough surface. Shape structure is likely to appear. Further, when the absorbance is small, the tendency to heat the entire workpiece becomes strong, or the laser beam absorption by the workpiece is reduced, so in the former case, the entire workpiece is melted, or in the latter case Since the temperature of the workpiece does not increase and melting does not occur, a fine uneven shape cannot be produced.

  Further, physical properties required for the workpiece will be described. In the present invention, since it is important that the melt generated on the surface does not spread on the surface due to the poor wettability of the surface, the poor wettability with respect to the generated melt is a desirable condition. This is because the melts generated on the surfaces do not stick to each other while maintaining a certain size due to poor wettability. In addition to poor wettability, a high vapor pressure is also a desirable condition.

Note that compounds having a relatively high vapor pressure include compounds containing oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, and the like. Specifically, as binary compounds, ZnO, ZnS, ZnSe, ZnTe, MgO, MgS, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SrO, SrS, SrSe, SrTe, BaO, BaS, BaSe, BaTe , AlN, AlP, AlS, GaN, GaP, GaAs, InN, InP, InAs, Y ₂ O ₃ , Y ₂ S ₃ , La ₂ O ₃ , La ₂ S _{3 and the} like. Further, as the ternary compound, MgAl ₂ O ₄ , MgAl ₂ S ₄ , MgAl ₂ Se ₄ , MgGa ₂ O ₄ , MgGa ₂ S ₄ , MgGa ₂ Se ₄ , MgIn ₂ O ₄ , MgIn ₂ S ₄ , MgIn ₂ Se ₄ , CaAl ₂ O ₄ , CaAl ₂ S ₄ , CaAl ₂ Se ₄ , CaGa ₂ O ₄ , CaGa ₂ S ₄ , CaGa ₂ Se ₄ , CaIn ₂ O ₄ , CaIn ₂ S ₄ , CaIn ₂ Se ₄ , SrAl _{2 O 4, SrAl 2 S 4} , SrAl 2 Se 4, SrGa 2 O 4, SrGa 2 S 4, SrGa 2 Se 4, SrIn 2 O 4, SrIn 2 S 4, SrIn 2 Se 4, BaAl 2 O 4, BaAl _{2 S 4, BaAl 2 Se 4} , BaGa 2 O 4, BaGa 2 S 4, BaGa 2 Se 4, _{aIn 2 O 4, BaIn 2 S} 4, BaIn 2 Se 4, Y 2 O 2 S, such as _La 2 _{O 2} S and the like.
These materials may have a composition in which each material is mixed in a predetermined amount. For example, Ga _x Al _1-x As, Sr (Ga _x In _1-x ) ₂ S _4, etc. may be used (where 0 <x <1). Various additive elements can also be added to these materials. For example, transition metals (Mn, Cu, Al, Ag, Au) and rare earth metals (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) can be used. These additive elements function as emission centers in the material, and emit light as phosphors when excited by various methods. In addition, examples of phosphors that are particularly effective for producing a fine uneven shape in order to improve light extraction efficiency include SrGa ₂ S ₄ : Eu, SrGa ₂ S ₄ : Ce, BaAl ₂ S ₄ : Eu, and the like. Can do.
However, the workpiece of the present invention is not limited to the above example.

Next, the relationship between the laser irradiation conditions and the fine uneven shape will be described. Under the laser irradiation conditions, it is necessary to create a temperature condition such that the fine uneven shape as described above grows. In addition, the energy density (unit: mJ / cm ² ) at the time of laser irradiation is a condition to be controlled. Roughly, as the energy density becomes larger than the melt density on the surface of the workpiece, the types of fine irregularities produced are sequentially hemispherical structure → cylindrical structure → kamaboko structure → rough surface structure. It tends to appear. And also in each structure, since the quantity of the melt which arises when an energy density becomes high, the magnitude | size of a structure changes. That is, as the energy density increases, the diameter of the hemisphere in the hemispherical structure increases, the diameter of the cylinder in the cylindrical structure increases, and the height of the kamaboko in the cylindrical structure tends to increase. Similarly, when the energy density increases, the amount of steam generated by surface evaporation increases and the ascending current becomes stronger, so that the interval and height of the structure change. In other words, as the energy density increases, the hemispherical spacing in the hemispherical structure is slightly wider, the spacing in the cylindrical tissue is slightly wider, the height of the cylindrical body is increased, and a gap is opened between the tops of the cylindrical structure. Tend. The kamaboko-shaped structure creates a gap between the kamaboko when the amount of melt is small, but the gap gradually closes as the amount of melt increases, the height of the kamaboko decreases, and eventually the kamaboko next Merge and flatten.

The condition to be controlled is the power density at the time of laser irradiation. The power density (unit: W / cm ² ) is obtained by dividing the irradiated energy density (unit: mJ / cm ² ) by the half width (unit: s) of the time width of the laser pulse, and the laser pulse irradiates the thin film. This is related to the rising speed and the reaching temperature of the surface temperature of the thin film. Therefore, if the power density is not high to some extent, a temperature rise enough to generate a melt on the surface of the thin film cannot be expected, so that the amount of the generated melt varies. This indicates that even if the energy density is the same, if the half width of the laser pulse time is changed, the fine structure that can be produced is different. That is, when the power density is large at the same energy density, the types of microstructures are sequentially shifted in the direction of “semispherical structure / cylindrical structure / kamaboko structure / rough structure”. In addition, when the power density is small with the same energy density, the type of the fine structure is shifted in the opposite direction.

  Next, the oscillation frequency of the laser pulse to be irradiated will be described. For the growth of the fine structure, the presence of the melt and the air flow consisting of surface evaporation by heating are important. For this reason, when the oscillation frequency is low, the heating effect on the surface is reduced and the temperature does not rise, which is not suitable. Similarly, in the growth of the fine structure, only the outermost surface of the surface is melted by heating, and the lower portion thereof needs to be maintained in a solid state without being melted. Therefore, heating and cooling of the surface can be performed by heating in a pulse manner. When the oscillation frequency is too high, the surface temperature remains elevated, and when the melt is generated, the entire surface is melted and covered with the melt. Also, among the oscillation frequencies that can be used for the production of fine structures, when the frequency is low, it is suitable for controlling the “hemispherical structure / cylindrical structure”, and when the frequency is high, the “kamaboko-shaped structure / rough shape” Suitable for organization control.

  In addition, the wavelength of the laser light also affects the formation of the fine uneven shape. That is, as the wavelength of the laser beam is longer, the heating effect appears in the deep part of the workpiece. Therefore, in the present invention, since it is desirable to heat only the surface layer of the workpiece, it is desirable to use laser light having a short wavelength, that is, a wavelength in the ultraviolet region.

The above-described energy density, power density, and the like vary depending on the characteristics of the workpiece to which the laser beam is irradiated as described above and the wavelength of the laser beam and the light penetration length with respect to the workpiece. For example, when a semiconductor such as Si or Ge, a compound semiconductor, or the like is used as a workpiece, the thickness at which the laser beam with the wavelength to be irradiated is absorbed by the material and attenuates to 10% is defined as L (nm). Assuming that the half width of the laser pulse is T (ns), as the laser light, for example, energy density L × 0.001 to 1 mJ / cm ² , power density L ÷ T × 1 to 1000 kW / cm ² , irradiation pulse frequency 20 The surface of the workpiece can be irradiated with the laser beam at ˜1000 Hz.
At this time, the irradiation pulse frequency as about 20～600Hz, generally, the energy density of the L × 0.001~0.4mJ / cm ^2, the power density of the ^{L ÷ T × 1~400kW / cm 2} , the workpiece A hemispherical fine concavo-convex structure can be formed on the surface of the material, the irradiation pulse frequency is about 20 to 600 Hz, the energy density of L × 0.01 to 0.6 mJ / cm ² , L ÷ T × 10 to 600 kW / cm ^With the power density of ^2, a cylindrical fine concavo-convex structure can be formed on the surface of the workpiece, the irradiation pulse frequency is about 50 to 1000 Hz, the energy density of L × 0.1 to 0.8 mJ / cm ² , L ÷ T the power density of × 100~800kW / cm ^2, the surface of the workpiece can be formed semicylindrical shape fine concave-convex structure, the illumination pulse frequency as about 50～1000Hz, Energy density of × 0.2~1mJ / cm ^2, the power density of the ^{L ÷ T × 200~1000kW / cm 2} , to form a rough surface fine irregular structure on the surface of the workpiece.

In addition, in the transition area | region of each shape, since it becomes a form where a shape changes gradually with differences in energy density etc., ranges, such as each energy density, overlap in part. Within the range of the energy density, by adjusting the density, the width and interval of each fine uneven shape can be adjusted.
Further, by changing the irradiation pulse frequency at that time, the total amount of energy given to the workpiece is changed, so that the fine rough surface shape can be controlled. That is, when the irradiation pulse frequency is lowered, the same tendency as the above-described energy density is reduced, and when the irradiation pulse frequency is increased, the same tendency as that of the above-described energy density is exhibited.

  Moreover, the present invention only needs to be able to form a fine uneven shape on the surface of the workpiece, and the workpiece can be used for various purposes. Preferably, the target can be a thin film semiconductor, and more preferably, a phosphor or a light emitter whose fine unevenness has a positive effect on optical characteristics can be targeted. An electric field using the phosphor An emissive display can be provided.

That is, according to the present invention, the surface of the workpiece is irradiated with laser light, and the surface layer of the workpiece is melted and solidified to form a fine uneven shape on the surface of the workpiece. By irradiating light, a material such as a thin film semiconductor in which a fine concavo-convex shape having a size equal to or smaller than the wavelength of the laser beam, for example, is directly formed on the surface of the workpiece.
As a result, photolithography used in semiconductor microfabrication is not required at all, and the surface of a workpiece such as a thin-film semiconductor can be directly microfabricated without using any complicated mask or resist coating or etching operations. It has an industrially excellent effect that a rough structure can be produced.

  Also, when an optical material is used as the work material, a fine uneven shape with a width of, for example, 1.5 μm or less can be formed on the surface, so that the light confinement effect is weakened and the light extraction efficiency is improved. Has the effect of Moreover, there is an effect that the light extraction efficiency of an arbitrary wavelength can be increased by selecting the width of the fine concavo-convex shape and the period of the structure according to the wavelength of the light to be extracted.

  In addition, if laser light having a wavelength in the ultraviolet region is used as the laser light, the vicinity of the surface of the thin film semiconductor can be heated efficiently. There is an effect that an uneven structure can be produced. In addition, the use of a high-power ultraviolet excimer laser has an advantage that a large area can be processed at a high speed because it is easy to obtain a high output even if it is shaped into a large beam shape.

  In addition, in the present invention, a workpiece such as a semiconductor can be crystallized (including recrystallization) by irradiating a laser beam simultaneously with the production of the fine uneven shape on the surface. The melted workpiece is cooled and crystallized, and the workpiece that has not melted at the base is heated until just before melting, thereby improving the crystallinity. Therefore, it is possible to improve the characteristics of a workpiece such as a thin film semiconductor. For example, phosphors and light emitters have a combined effect that stronger light emission can be obtained by the above-described action. There is an advantage that it can be processed simultaneously in the process.

Furthermore, when the thin film semiconductor is used as the workpiece and is used as the thin film phosphor of the anode of a field emission display, it is generated inside the thin film phosphor when the thin film phosphor is excited by a low-energy electron beam. The emitted light can be efficiently extracted from the substrate surface. Therefore, by adopting the thin film semiconductor of the present invention, there is an industrially excellent effect that it can be manufactured as an FED with high emission luminance and low power consumption even when driven at a low voltage.
In addition, if necessary, an antistatic film mainly composed of metal is provided on the surface of the thin film phosphor having a textured structure, so that the light extracted from the surface on which the textured surface is formed is reflected, and the phosphor screen of the display You may make it increase further the light taken out to the opposite side used as the side.

(Embodiment 1-1)
Below, one Embodiment of this invention is described based on FIGS. 1-3.
FIG. 1A shows a thin film semiconductor 10 as a workpiece before producing a fine uneven structure. At this time, the thin film semiconductor 10 is formed on the substrate 20 by a known method, and the thin film semiconductor 10 forms a structure with fine irregularities in the same manner as described below, regardless of whether it has crystallinity. can do.

The aforementioned thin film semiconductor 10, is irradiated for example energy density L × 0.001~0.4mJ / cm ^2, power density ^{L ÷ T × 1~400kW / cm 2} , the laser beam 30 irradiation pulse frequency 20~600Hz . Prior to laser irradiation, the thin film semiconductor 10 may be preheated with a heater, a lamp, or another heating means. The situation during laser irradiation is shown in FIG. Due to the laser irradiation, heat is generated by the absorption of the laser beam 30 on the surface of the thin film semiconductor 10, and a molten semiconductor 10a is generated near the surface. By using an ultraviolet laser as a laser beam to be used, energy absorption occurs in the vicinity of the surface of the thin film semiconductor 10, so that there is an advantage that the molten semiconductor 10 a is generated earlier. At this time, the molten semiconductor 10a on the unmelted thin film semiconductor 10 which is a solid phase is scattered on the thin film semiconductor 10 due to poor wettability on the solid, and is agglomerated and melted by its own surface tension. Make a collection of liquids.

  Furthermore, the change in the situation during laser irradiation is shown in FIG. The melted semiconductor 10a, which is a collection of melts scattered on the thin film semiconductor 1, is swung by the air current of the components evaporated from the surface, coalesces with each other and gradually increases in size, and each is self-organized and uniform. Grow while maintaining size and distance. Thus, a hemispherical shape is formed on the solid in a self-organizing manner.

  The state change after laser irradiation is shown in FIG. The surface of the thin film semiconductor 10 is heated to the temperature just before melting, and the crystallinity is improved, and the melt forms a hemispherical fine irregular shape in a self-organized manner, and then cooled and recrystallized. It consists of a part that has become. Therefore, in the vicinity of the surface, formation of the fine uneven shape 10b and annealing effects such as improvement of crystallinity and recrystallization are performed simultaneously.

In a portion where crystallinity is improved or a portion where recrystallization is performed, characteristics as a semiconductor are improved, and in a phosphor or the like, light emission characteristics are improved. Therefore, stronger light emission from a semiconductor or phosphor can be obtained. In addition, a hemispherical structure having an arbitrary size can be formed at an arbitrary interval depending on the irradiation time and energy density of the laser, the amount of thin film semiconductor to be melted, and the physical properties of the thin film semiconductor. By producing a hemispherical structure, the effect of confining the light emission generated inside the thin film semiconductor is weakened, and the light extraction efficiency from the inside of the thin film semiconductor can be improved. In addition, by adjusting the laser irradiation time, the energy density, the irradiation pulse frequency, etc., the size and interval of the hemispherical structure is controlled, and the surface of the thin film semiconductor is made a photonic crystal structure. Stronger light emission can be extracted from the inside of the thin film semiconductor.
Through this series of processes, a thin film semiconductor having a hemispherical structure can be obtained by scanning with a laser shaped into a line beam shape capable of large area processing without using any photolithography, mask, resist, or etching. Can be created over large areas.

FIG. 2 shows a thin film semiconductor 10 having a hemispherical fine unevenness 10b on the surface obtained by the above manufacturing method. An embodiment in which the thin film semiconductor 10 is used as a thin film phosphor 100 of a field emission display (field emission display) will be described.
As a material for the thin film semiconductor, a normal semiconductor material such as Si or Ge or a so-called wide band gap compound semiconductor having a large band gap can be used, and a luminescent center element is added to a binary compound or a ternary compound. The produced thin film phosphor can also be used. At this time, as the substrate, any substrate such as various substrates used when forming a thin film semiconductor, a glass substrate, a glass substrate with a transparent electrode, and the like can be used.

  FIG. 3 shows an anode panel including a thin film phosphor 100 of a field emission display. The anode panel includes a transparent substrate 21 and a transparent electrode 22 and includes the thin film phosphor 100 made of the thin film semiconductor 10. . The thin film phosphor 100 may have a structure partitioned by a black matrix 23 as shown in FIG. In this figure, the antistatic film 24 is provided on the upper side of the thin film phosphor 100. However, when the acceleration voltage of the electron beam is as low as several kV or less, the antistatic film 24 can be omitted. . Since the thin-film phosphor 100 emits an electron beam from a predetermined cathode, not shown, from the upper side of the anode panel in FIG. 3, the thin-film phosphor 100 is appropriately excited by the electron beam and emits light. This can be seen through the transparent electrode 22 and the transparent substrate 21.

(Embodiment 1-2)
Hereinafter, the manufacturing method of the thin film semiconductor according to the first to second embodiments will be described.
FIG. 4A shows the structure of the thin film semiconductor 11 before a hemispherical structure is formed. At this time, the thin film semiconductor 11 is formed on the substrate 20 by a known method, and the thin film semiconductor 11 has a thin film structure as shown in the drawing. In the structure inside the thin film, a dense portion and a sparse portion are formed as shown in the figure, and the density and thermal conductivity are slightly different in each portion. A thin film having such a structure can be manufactured by a known film forming method by appropriately selecting the film forming conditions.

  The thin film semiconductor 11 is irradiated with a laser beam 30 having a uniform intensity distribution. Prior to laser irradiation, the thin film semiconductor may be preheated with a heater, a lamp, or another heating means. The situation during laser irradiation is shown in FIG. By irradiation with the laser beam 30, heat is generated by the absorption of the laser beam 30 on the surface of the thin film semiconductor 11, and a molten semiconductor 11a is generated near the surface. In the dense part of the semiconductor structure existing in the thin film semiconductor 11, heat is easily transmitted in the direction shown in the figure, and in the sparse part of the semiconductor structure, heat is relatively likely to be stored, so that melting occurs first. The molten semiconductor 11a on the unmelted thin film semiconductor 11 which is a solid phase is scattered on the thin film semiconductor 11 due to poor wettability on the solid, and on a dense portion of the semiconductor structure whose temperature is slightly lower. It collects easily by its own surface tension and forms a collection of melts.

  Furthermore, the situation during laser irradiation is shown in FIG. The melted semiconductor 11a, which is a collection of melts scattered on the thin film semiconductor 11, is swayed by the air current of the component evaporated from the surface, and gradually merges with the melt gathered on the dense portion of the semiconductor structure. As the size increases, each grows with self-organizing equal size and distance. Thus, a hemispherical shape is formed on the solid in a self-organizing manner.

The state after laser irradiation is shown in FIG. On the surface of the thin film semiconductor 11, a portion having improved crystallinity because of being heated to a temperature just before melting, and the melt forms a hemispherical fine uneven shape 11 b in a self-organized manner, and then cooled and re-cooled. It consists of crystallized parts. Therefore, in the vicinity of the surface, formation of fine irregularities and an annealing effect such as improvement of crystallinity and recrystallization are simultaneously performed.
In a portion where crystallinity is improved or a portion where recrystallization is performed, characteristics as a semiconductor are improved, and in a phosphor or the like, light emission characteristics are improved. Therefore, stronger light emission from a semiconductor or phosphor can be obtained.

(Embodiment 2-1)
In Embodiments 1-1 and 2 described above, the case of forming a hemispherical fine uneven shape on the surface of a thin film semiconductor that is a workpiece has been described. Below, the method of forming a cylindrical fine uneven | corrugated shape as a fine uneven | corrugated shape is demonstrated based on FIG.

  FIG. 5A shows a thin film semiconductor 12 as a workpiece before producing a fine uneven structure. At this time, the thin film semiconductor 1 is formed on the substrate 2 by a well-known method, and the thin film semiconductor 1 forms a fine concavo-convex shape in the same manner by the following process, whether or not it has crystallinity. can do.

That is, the thin film semiconductor 1, for example, the energy density L × 0.01~0.6mJ / cm ^2, power density ^{L ÷ T × 10~600kW / cm 2} , the laser beam 30 irradiation pulse frequency 20~600Hz irradiation To do. Prior to laser irradiation, the thin film semiconductor 12 may be preheated with a heater, a lamp, or another heating means. The situation during laser irradiation is shown in FIG. The irradiation with the laser beam 30 generates heat due to the absorption of the laser beam 30 on the surface of the thin film semiconductor 12, and a molten semiconductor 12 a is generated near the surface. By using an ultraviolet laser as a laser beam to be used, energy absorption occurs in the vicinity of the surface of the thin film semiconductor 12, so that there is an advantage that the molten semiconductor 12 is generated earlier. At this time, the melted semiconductor 12a on the unmelted thin film semiconductor 12 that is a solid phase is scattered on the thin film semiconductor 12 due to poor wettability on the solid, and is agglomerated and melted by its own surface tension. Make a collection of liquids.
Further, the melted semiconductor 12a is shaken by the air current of the component evaporated from the surface, and unites with each other to gradually increase in size, and grows while maintaining a uniform size and distance from each other.

  Furthermore, the situation during laser irradiation is shown in FIG. The melted semiconductor 12a grown in a self-organized manner is supplied with the melted semiconductor 12a from the surface, and is blown up by a violent ascending current created by a component evaporated from the surface as shown in the figure to increase the volume upward. It grows upward within a range where the balance between the upward growth by blowing up the upward air flow and the force of the upwardly extending melt portion to be crushed downward can be balanced. Thus, a cylindrical shape is formed in a self-organized manner on the solid.

The state after laser irradiation is shown in FIG. On the surface of the thin film semiconductor 12, a portion where the crystallinity has been improved due to being heated to a temperature just before melting, and the melt forms a cylindrical concavo-convex shape 12 b in a self-organized manner, and is then cooled and reused. It consists of crystallized parts. Therefore, in the vicinity of the surface, formation of fine irregularities and an annealing effect such as improvement of crystallinity and recrystallization are simultaneously performed.
In a portion where crystallinity is improved or a portion where recrystallization is performed, characteristics as a semiconductor are improved, and in a phosphor or the like, light emission characteristics are improved. Therefore, stronger light emission from a semiconductor or phosphor can be obtained. In addition, a columnar structure having an arbitrary size can be formed at an arbitrary interval depending on the irradiation time and energy density of the laser, the amount of thin film semiconductor to be melted, and the physical properties of the thin film semiconductor. By producing a cylindrical structure, the effect of confining the light emitted inside the thin film semiconductor was weakened, and the light extraction efficiency from the inside of the thin film semiconductor could be improved. Further, by controlling the size and interval of the columnar structure and making the surface of the thin film semiconductor have a photonic crystal structure, stronger light emission can be extracted from the inside of the thin film semiconductor.

  FIG. 6 shows a thin film semiconductor 12 having a hemispherical fine irregular shape 12b on the surface obtained by the above manufacturing method. The thin film semiconductor 12 can be used as a thin film phosphor of a field emission display (field emission display), and the material of the thin film semiconductor is the same as described above.

  FIG. 7 shows an anode panel provided with a thin film phosphor of a field emission display, and has a thin film phosphor 120 made of the thin film semiconductor 12. The thin film phosphor 120 emits an electron beam from a predetermined cathode, not shown, from the upper side of the anode panel in FIG. The transparent electrode 22 and the transparent substrate 21 can be seen through with good light extraction efficiency. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.

(Embodiment 2-2)
In addition, as in the above-described embodiment, the cylindrical concavo-convex shape has a dense part and a sparse part in the structure inside the thin film, and the density and thermal conductivity are slightly different in each part. Can be formed. The surface of the thin film semiconductor after the laser irradiation is affected by the distribution of the dense and sparse portions, and a cylindrical fine uneven shape is obtained. Also, the inner layer is heated to the temperature just before melting. It consists of a portion where the crystallinity is improved and a portion where the melt forms a hemispherical structure in a self-organized manner and is then cooled and recrystallized. Therefore, in the vicinity of the surface, formation of fine irregularities and an annealing effect such as improvement of crystallinity and recrystallization are simultaneously performed. In a portion where crystallinity is improved or a portion where recrystallization is performed, characteristics as a semiconductor are improved, and in a phosphor or the like, light emission characteristics are improved.

(Embodiment 3-1)
In Embodiments 2-1 and 2 described above, the case of forming a cylindrical fine concavo-convex shape on the surface of a thin film semiconductor that is a workpiece has been described. Below, the method of forming the fine uneven | corrugated shape of the kamaboko shape (longitudinal cross-sectional hemisphere) as a fine uneven | corrugated shape is demonstrated based on FIG.

  FIG. 8A shows a thin film semiconductor 13 as a workpiece before producing a fine uneven structure. At this time, the thin film semiconductor 13 is formed on the substrate 20 by a known method, and the thin film semiconductor 13 forms a fine uneven structure in the same manner by the following processing, whether or not it has crystallinity. can do.

That is, the thin film semiconductor 1 is spatially intensified, for example, with an energy density L × 0.1 to 0.8 mJ / cm ² , power density L ÷ T × 100 to 800 kW / cm ² , and an irradiation pulse frequency of 50 to 1000 Hz. A laser beam 31 having a distribution is irradiated. Prior to the laser irradiation, the thin film semiconductor 13 may be preheated by a heater, a lamp, or another heating means. The situation during laser irradiation is shown in FIG. As the laser beam 31 having a spatial intensity distribution, a laser beam having a distribution in which the laser intensity decreases from the left side to the right side in the figure is used. The irradiation with the laser beam 31 generates heat due to the absorption of the laser beam 31 on the surface of the thin film semiconductor 13, and a molten semiconductor 13 a is generated near the surface. By using an ultraviolet laser as a laser beam to be used, energy absorption occurs near the surface of the thin film semiconductor 13, so that there is an advantage that the molten semiconductor 13 a is generated earlier. At this time, the melted semiconductor 13a on the unmelted thin film semiconductor 13 which is a solid phase is scattered on the thin film semiconductor 13 due to poor wettability on the solid, and agglomerated and melted by its own surface tension. Make a collection of liquids. Further, the melted semiconductor 13a sways by the air current of the component evaporated from the surface, coalesces with each other and gradually increases in size, and grows while maintaining a uniform size and distance from each other.

  The situation during laser irradiation is shown in FIG. The melted semiconductor 13a that has grown linearly in a self-organized manner is supplied with the melted semiconductor 13 from the surface, and is blown up by a violent ascending current created by a component evaporated from the surface as shown in the figure. , And grow upward in a range that balances the upward growth by blowing up the upward air flow and the force that the melted portion that extends downward is crushed downward.

  Furthermore, the situation during laser irradiation is shown in FIG. Since the structures grown above the melted semiconductor 13a are evenly arranged in a self-organized manner, the structure of the semiconductor 13a that has melted linearly is collapsed when the tissues that have grown up sequentially in the direction of collapse and coalescence fall down. It is formed. At the same time, since the heat is continuously generated on the surface of the thin film semiconductor 13 by the laser beam 31 having a spatially distributed intensity, the melted semiconductor 13a is absorbed by the linearly melted semiconductor structure. The capacity is gradually increased, but since the ascending airflow due to the evaporation component is blowing up between the linearly aligned tissues, the linearly melted structure exists while maintaining its shape.

  As shown in FIG. 8E, the linearly melted structure gradually collapses in the downward direction because the ascending airflow is weakened after the irradiation of the laser beam, but the thin film semiconductor surface is wetted. It cools while maintaining its shape due to its poor nature and the surface tension of the melt, and solidifies without fusing with the adjacent tissue. Thus, a long and semi-spherical shape is formed on the solid in a self-organizing manner. However, in a place where the capacity of the semiconductor structure melted linearly becomes too large and the shape cannot be maintained due to the rising airflow blowing between the structures, it fuses with the adjacent structures and is linear. Therefore, the shape of the structure of the melted semiconductor cannot be maintained, and the surface of the thin-film semiconductor 13 is completely consumed by the melted semiconductor and flattened.

FIG. 8F shows the state after laser irradiation. On the surface of the thin film semiconductor 10, a portion having improved crystallinity due to being heated to a temperature just before melting and a fine irregular shape 13 b having a kamaboko shape in a self-organized manner are formed, and then cooled and re-cooled. It consists of crystallized parts. Therefore, in the vicinity of the surface, formation of fine irregularities and an annealing effect such as improvement of crystallinity and recrystallization are simultaneously performed.
In a portion where crystallinity is improved or a portion where recrystallization is performed, characteristics as a semiconductor are improved, and in a phosphor or the like, light emission characteristics are improved. Further, depending on the laser irradiation time and energy density, the amount of thin-film semiconductor to be melted, and the physical properties of the thin-film semiconductor, a kamaboko-shaped structure having an arbitrary size can be created at an arbitrary interval. By manufacturing the kamaboko-shaped structure, the effect of confining the light emitted inside the thin film semiconductor is weakened, and the light extraction efficiency from the inside of the thin film semiconductor can be improved. Further, by controlling the size and interval of the kamaboko-shaped structure so that the surface of the thin film semiconductor has a photonic crystal structure, stronger light emission can be extracted from the inside of the thin film semiconductor.

FIG. 9 shows a thin film semiconductor 13 having a kamaboko-shaped fine uneven shape 13b on the surface obtained by the above-described manufacturing method. The thin film semiconductor 13 can be used as a thin film phosphor of a field emission display (field emission display), and the material of the thin film semiconductor is the same as described above.
FIG. 10 shows an anode panel provided with a thin film phosphor of a field emission display, and has a thin film phosphor 130 made of the thin film semiconductor 13. The thin film phosphor 130 emits an electron beam from a predetermined cathode, not shown, from the upper side of the anode panel shown in FIG. The transparent electrode 22 and the transparent substrate 21 can be seen through with good light extraction efficiency. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.

Embodiment 3-2
The kamaboko-shaped fine uneven shape has a dense portion and a sparse portion in the structure inside the thin film, as in the above embodiment, and the thin film semiconductor 14 having a slightly different density and thermal conductivity in each portion. Can be formed on the subject. The thin film semiconductor 14 is shown in FIG.

  When the thin film semiconductor 14 is irradiated with the laser beam 30 having a uniform intensity distribution, as shown in FIG. 11B, heat is transferred to the inner layer in a dense portion of the semiconductor structure existing in the thin film semiconductor 14. It is easy to transmit, and heat tends to stay in the sparse part of the semiconductor structure, so melting occurs first. At this time, the molten semiconductor 14a on the unmelted thin film semiconductor 14 which is a solid phase is scattered on the thin film semiconductor 14 due to poor wettability on the solid, and the semiconductor structure having a slightly lower temperature is dense. It is easy to gather on the part, and it aggregates by its own surface tension to form a melt. Further, the melted semiconductor 14a is shaken by the air current of the component evaporated from the surface, and unites with each other to gradually increase in size, and grows while maintaining a uniform size and distance from each other. When the structure inside the thin film semiconductor 14 has a linear structure, the melt collected on the thin film semiconductor grows linearly in a self-organized manner.

  As shown in FIG. 11 (c), the melted semiconductor 14a grown linearly in a self-organized manner is supplied with the melted semiconductor from the surface, and as shown in FIG. The volume is increased upward as it is blown up by the air flow, but the rising air flow from the evaporating component is blowing up between the linearly aligned tissues, so that the linearly melted structure maintains its shape. Exist.

  As shown in FIG. 11 (d), the linearly melted structure gradually collapses in the downward direction because the rising airflow is weakened as shown in FIG. 11 (d). It cools while maintaining its shape due to its poor nature and the surface tension of the melt, and solidifies without fusing with the adjacent tissue. In this way, a fine concave-convex shape 14b having a semispherical cross-sectional hemispherical shape is formed on the solid.

(Embodiment 4-1)
Next, a description will be given of the case of forming a rough concavo-convex shape on the surface of a thin film semiconductor, which is a workpiece, with reference to FIGS.
FIG. 12 (a) shows a thin film semiconductor 15 as a workpiece before producing a fine uneven structure. At this time, the thin film semiconductor 15 is formed on the substrate 20 by a known method, and the thin film semiconductor 15 forms a fine concavo-convex shape in the same manner by the following process, whether or not it has crystallinity. can do.

That is, the thin film semiconductor 15 is irradiated with the laser beam 30 at, for example, energy density L × 0.2 to 1 mJ / cm ² , power density L ÷ T × 200 to 1000 kW / cm ² , and irradiation pulse frequency 50 to 1000 Hz. Prior to the laser irradiation, the thin film semiconductor 15 may be preheated with a heater, a lamp, or another heating means. The situation during laser irradiation is shown in FIG. The irradiation with the laser beam 30 generates heat due to the absorption of the laser beam 30 on the surface of the thin film semiconductor 15, and a molten semiconductor 15a is generated near the surface. By using an ultraviolet laser as a laser beam to be used, energy absorption occurs in the vicinity of the surface of the thin film semiconductor 15, so that there is an advantage that the molten semiconductor 15 a is generated earlier. At this time, the melted semiconductor 15a on the unmelted thin film semiconductor 15 which is a solid phase is scattered on the thin film semiconductor 15 due to poor wettability on the solid, and agglomerated and melted by its own surface tension. Make a collection of liquids. Further, the melted semiconductor 15a is shaken by the air current of the component evaporated from the surface, unites with each other and gradually increases in size, and grows while maintaining a uniform size and distance from each other.

  Furthermore, the situation during laser irradiation is shown in FIG. Under the melt of the melted semiconductor 15a that grows linearly in a self-organized manner, the influence of the laser light is reduced, and as shown in FIG. In response to the supply of the melted semiconductor 15a from the surface, the amount of the melt is increased. As the amount of the melt increases, the melts finally merge and the melted semiconductor 15a covers the surface of the unmelted thin film semiconductor 15. In this way, a rough uneven surface having a rough surface shape is formed on the surface of the unmelted thin film semiconductor 15.

The state after laser irradiation is shown in FIG. On the surface of the thin film semiconductor 10, a portion having improved crystallinity because of being heated to a temperature just before melting, and a fine uneven shape having a rough surface shape in which the melt is complex in a self-organizing manner, and then cooled. It consists of a solidified (or recrystallized) part. Therefore, in the vicinity of the surface, the formation of the rough uneven shape 15b having a rough surface shape and an annealing effect such as improvement of crystallinity and recrystallization are performed simultaneously.
In a portion where crystallinity is improved or a portion where recrystallization is performed, characteristics as a semiconductor are improved, and in a phosphor or the like, light emission characteristics are improved. Therefore, stronger light emission from a semiconductor or phosphor can be obtained. Further, rough structures having different sizes can be created depending on the irradiation time and energy density of the laser, the amount of thin film semiconductor to be melted, and the physical properties of the thin film semiconductor.

FIG. 13 shows a thin film semiconductor 15 obtained by the above manufacturing method and having a rough concavo-convex shape 15b on the surface. The thin film semiconductor 15 can also be used as a thin film phosphor of a field emission display (field emission display), and the material of the thin film semiconductor is the same as described above.
FIG. 14 shows an anode panel provided with a thin film phosphor of a field emission display, and has a thin film phosphor 150 made of the thin film semiconductor 15. The thin film phosphor 150 emits an electron beam from a predetermined cathode, not shown, from the upper side of the anode panel shown in FIG. The transparent electrode 22 and the transparent substrate 21 can be seen through with good light extraction efficiency. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.

(Embodiment 4-2)
In addition, the kamaboko-shaped fine uneven shape has a dense portion and a sparse portion in the structure inside the thin film, as in the above embodiment, and is intended for thin film semiconductors in which the density and thermal conductivity are slightly different in each portion. Can be formed.
On the surface of a thin film semiconductor during laser irradiation, heat is easily transmitted in a dense part of the semiconductor structure existing in the thin film semiconductor, and heat is relatively confined in a sparse part of the semiconductor structure. Occurs. At this time, the melted semiconductor on the unmelted thin film semiconductor that is a solid phase is scattered on the thin film semiconductor due to poor wettability on the solid body, and tends to gather in a dense part of the semiconductor structure at a slightly lower temperature. , It aggregates by its own surface tension and creates a collection of melts. Further, the melted semiconductors sway in the air stream of the components evaporated from the surface, merge with each other and gradually increase in size, and each grows while maintaining a uniform size and distance from each other.

  Since the influence of the laser light is reduced under the melt of the molten semiconductor that grows linearly in a self-organized manner, a part that remains undissolved by the influence of the molten semiconductor is formed, and the melted semiconductor from the surface Receive the supply to increase the amount of melt. As the amount of the melt increases, the melts finally merge and cover the surface of the thin film semiconductor that is not melted by the melted semiconductor. Thus, a rough surface structure is formed on the surface of the unmelted thin film semiconductor in a self-organizing manner.

  In the situation immediately after the laser irradiation is stopped, the temperature of the melted semiconductor or thin film semiconductor gradually decreases because the supply of heat by the laser irradiation is cut off. In particular, a convex portion of a thin film semiconductor in which a rough-surfaced structure is formed in a self-organized manner has a dense semiconductor structure, so that the temperature is rapidly lowered due to the rapid movement of heat. Therefore, in the surface of the thin film semiconductor, a local temperature gradient is generated due to the influence of the difference in thermal conductivity characteristics of the base and the uneven structure, so that solidification starts from the convex portion having a low temperature. At this time, crystallization also proceeds simultaneously depending on the semiconductor material. The solidification of the molten semiconductor proceeds in a self-organized manner in the direction of the growth of the crystal structure, that is, from the convex part of the thin film semiconductor to the melted semiconductor, influenced by the underlying uneven structure and temperature gradient. Go. And all the melted semiconductors solidify and form a complex uneven structure on the surface.

Hereinafter, a thin film phosphor SrGa ₂ S ₄ : Eu was manufactured as the thin film semiconductor according to the first to fourth embodiments. The thin film phosphor (SrGa ₂ S ₄ : Eu) was formed on the substrate by a known method. Even if the thin film phosphor does not have crystallinity at the time of film formation, it is a material (SrS and GaS or Ga ₂ S ₃ , additive, even if it is a compound semiconductor that is the target phosphor) In the same way, a hemispherical structure made of a compound semiconductor could be produced in the subsequent treatment.

The thin film phosphor is irradiated with KrF excimer laser light as described in the above embodiment. Prior to laser irradiation, the thin film phosphor may be preheated with a heater, a lamp, or another heating means. The laser irradiation generates heat due to the absorption of the KrF laser light on the surface of the thin film phosphor (SrGa ₂ S ₄ : Eu), and a molten phosphor (SrGa ₂ S ₄ : Eu) is generated near the surface. As a laser beam to be used, a laser beam having an arbitrary wavelength can be used, and an XeF excimer laser having a wavelength of 351 nm, an XeCl excimer laser having a wavelength of 309 nm, or the like can be used. However, since the depth at which the laser light penetrates into the substance differs depending on the wavelength of the laser light to be used, the amount of the melt that melts at the time of laser irradiation differs. Therefore, by selecting the type of laser, it is possible to create a fine concavo-convex shape having an arbitrary size while maintaining an arbitrary interval.

  In the following, fine uneven shapes were produced by the same mechanism as described in the first to fourth embodiments.

Example 1
Laser light having a uniform intensity distribution according to the conditions of a laser beam wavelength of 248 nm, an energy density of 10 mJ / cm ² , a power density of 0.5 MW / cm ² (pulse half width 20 ns), a pulse frequency of 100 Hz, and a pulse irradiation number of 30000 shots. Was irradiated to the thin film phosphor. At this time, the phosphor substrate was heated to 500 ° C., and the laser irradiation was performed in an atmosphere of argon and 10% hydrogen sulfide.
As a result, a hemispherical structure having a size of about 200 nm could be created with a gap in accordance with this example. By producing a hemispherical structure, the effect of confining the light emitted inside the thin film phosphor was weakened, and the light extraction efficiency from the inside of the thin film phosphor could be improved. In addition, by controlling the size and interval of the hemispherical structure and making the surface of the thin film phosphor a photonic crystal structure, it was possible to extract stronger light emission from the inside of the thin film phosphor.

  FIG. 15 is a drawing-substituting photograph obtained with a scanning electron microscope (SEM) showing the surface of the phosphor obtained above. As seen in the photograph, it can be seen that a hemispherical fine irregular shape is formed on the surface of the phosphor.

(Example 2)
Next, a uniform intensity distribution is obtained according to the conditions of the laser beam wavelength of 248 nm, the energy density of 15 mJ / cm ² , the power density of 0.75 MW / cm ² (pulse half width 20 ns), the pulse frequency of 100 Hz, and the pulse irradiation number of 30000 shots. The thin film phosphor was irradiated with a laser beam. At this time, the phosphor substrate was heated to 500 ° C., and the laser irradiation was performed in an atmosphere of argon and 10% hydrogen sulfide.
As a result, a columnar structure having a diameter of about 200 nm and a height of about 500 nm could be created at a certain interval according to this example. By producing a cylindrical concavo-convex shape, the light extraction efficiency from the inside of the thin film phosphor could be improved. In addition, by controlling the size and interval of the hemispherical structure and making the surface of the thin film phosphor a photonic crystal structure, it was possible to extract stronger light emission from the inside of the thin film phosphor.

  FIG. 16 is a drawing-substituting photograph obtained with a scanning electron microscope (SEM) showing the surface of the phosphor obtained above. As can be seen in the photograph, it can be seen that a cylindrical concavo-convex shape is formed on the surface of the phosphor.

Example 3
Next, the laser beam wavelength is 248 nm, the energy density is 20 mJ / cm ² , the power density is 1 MW / cm ² (pulse half width 20 ns), the pulse frequency is 100 Hz, and the pulse irradiation number is 30000 shots, and there is an inclined intensity change. The thin film phosphor was irradiated with laser light. At this time, the phosphor substrate was heated to 500 ° C., and the laser irradiation was performed in an atmosphere of argon and 10% hydrogen sulfide.
According to the present embodiment, a straight kamaboko shape having a width of about 100 nm could be created with a gap. It was possible to improve the light extraction efficiency from the inside of the thin film phosphor by producing a kamaboko-shaped fine uneven shape. In addition, by controlling the size and interval of the kamaboko-shaped structure and making the surface of the thin film phosphor a photonic crystal structure, it was possible to extract stronger light emission from the inside of the thin film phosphor.

  FIG. 17 is a drawing-substituting photograph obtained with a scanning electron microscope (SEM) showing the surface of the phosphor obtained above. As seen in the photograph, it can be seen that the surface of the phosphor has a kamaboko-shaped fine irregular shape.

Example 4
Next, with the conditions of the laser beam wavelength of 248 nm, the energy density of 40 mJ / cm ² , the power density of 2 MW / cm ² (pulse half width 20 ns), the irradiation pulse frequency of 100 Hz, and the number of pulse irradiations of 30000 shots, the inclined intensity change The thin film phosphor was irradiated with a laser beam having the same.
At this time, the phosphor substrate was heated to 500 ° C., and the laser irradiation was performed in an atmosphere of argon and 10% hydrogen sulfide.
According to this example, a fine uneven shape having a rough surface shape could be created. It was possible to improve the light extraction efficiency from the inside of the thin film phosphor by producing a rough uneven surface with a rough surface. Further, by controlling the size and interval of the rough surface shape and making the surface of the thin film phosphor have a photonic crystal structure, it was possible to extract stronger light emission from the inside of the thin film phosphor.

In each of the above embodiments, even when an aggregate of materials (including SrS and GaS or Ga ₂ S ₃ and additive Eu) is used as the thin film phosphor, a melt obtained by melting the material In the solidified portion, a fine uneven shape made of a thin film phosphor (SrGa ₂ S ₄ : Eu) could be created. In addition, since the thin film semiconductor portion made of a raw material that is not melted is heated to a temperature just before melting, the compound semiconductor from the raw material (including SrS and GaS or Ga ₂ S ₃ and additive Eu) It was possible to synthesize a phosphor (SrGa ₂ S ₄ : Eu). Therefore, in the vicinity of the surface, formation of fine irregularities, synthesis of a compound semiconductor, and annealing effects such as improvement of crystallinity and recrystallization could be performed simultaneously.

Thus, even when the thin film semiconductor is a compound semiconductor composed of three or more elements, a thin film semiconductor having a hemispherical structure could be formed in the same manner. As another thin film semiconductor, AB ₂ C ₄ : L (A = Mg, Ca, Sr, Ba, B = Al, Ga, In C═O, S, Se, Te L: rare earth metal element or transition metal element The same effect was also obtained in a series of compound semiconductors.

  The present invention has been described based on the above embodiments and examples. However, the present invention is not limited to the contents of the above embodiments and examples, and does not depart from the scope of the present invention. Appropriate changes are possible.

It is a flowchart which shows the manufacture process of one Embodiment of this invention. Similarly, it is a figure which shows the thin film semiconductor obtained in the said manufacture process and having the fine uneven | corrugated shape on the surface. Similarly, it is a figure which shows the partial structure of the field effect type display which used the thin film semiconductor obtained above as fluorescent substance. It is a flowchart which shows the manufacture process of other embodiment of this invention. It is a flowchart which shows the manufacture process of further another embodiment of this invention. Similarly, it is a figure which shows the thin film semiconductor obtained in the said manufacture process and having the fine uneven | corrugated shape on the surface. Similarly, it is a figure which shows the partial structure of the field effect type display which used the thin film semiconductor obtained above as fluorescent substance. It is a flowchart which shows the manufacture process of further another embodiment of this invention. Similarly, it is a figure which shows the thin film semiconductor obtained in the said manufacture process and having the fine uneven | corrugated shape on the surface. Similarly, it is a figure which shows the partial structure of the field effect type display which used the thin film semiconductor obtained above as fluorescent substance. It is a flowchart which shows the manufacture process of further another embodiment of this invention. It is a flowchart which shows the manufacture process of further another embodiment of this invention. Similarly, it is a figure which shows the thin film semiconductor obtained in the said manufacture process and having the fine uneven | corrugated shape on the surface. Similarly, it is a figure which shows the partial structure of the field effect type display which used the thin film semiconductor obtained above as fluorescent substance. It is a drawing substitute photograph which shows the surface shape of the thin film semiconductor obtained by the Example of this invention. Similarly, it is the drawing substitute photograph which shows the surface shape of the thin film semiconductor obtained by the other Example. Similarly, it is the drawing substitute photograph which shows the surface shape of the thin film semiconductor obtained by the other Example.

Explanation of symbols

10, 11, 12, 13, 14, 15 Thin film semiconductor
10a, 11a, 12a, 13a, 14a, 15a Melted semiconductor 10b, 11b, 12b, 13b, 14b, 15b Fine uneven shape
20 Substrate 30 Laser light 31 Laser light 100, 110, 120, 130, 140, 150 Thin film phosphor

Claims (10)

  The surface of the workpiece is irradiated with a laser beam, and the surface layer of the workpiece is melted and solidified to form a micro uneven shape on the surface of the workpiece. Production method.   The method for producing a fine surface uneven shape material according to claim 1, wherein the fine uneven shape has a size equal to or smaller than a wavelength of laser light.   The fine uneven surface material according to claim 1 or 2, wherein the fine uneven shape is one or more kinds of hemispherical shape, cylindrical shape, or kamaboko shape arranged side by side. Production method.   4. The method of manufacturing a fine surface uneven shape material according to claim 3, wherein the kamaboko shape has a length larger than a width.   5. The method for producing a fine surface uneven shape according to claim 3, wherein the fine convex shape has a width of 1.5 [mu] m or less.   6. The method for producing a fine surface irregular shape material according to claim 1, wherein the laser beam has a wavelength in an ultraviolet region.   The method for producing a fine surface uneven shape material according to claim 1, wherein the workpiece is crystallized by laser light irradiation.   8. The method for producing a fine surface uneven shape material according to claim 1, wherein the workpiece is a thin film semiconductor.   The method for producing a fine surface uneven shape material according to any one of claims 1 to 8, wherein the workpiece is a phosphor or a light emitter.   10. A field emission display comprising the phosphor manufactured according to claim 9 arranged on the anode side with a fine surface irregularity shape on the electrolytic emission side.