JP2007150053A - Stamper for optical inprint, and manufacturing method for light emitting device and using same stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stamper and a manufacturing method using the stamper wherein the process for exfoliating the stamper from a substrate can be performed highly precisely and easily in the manufacturing process for semiconductor devices, with respect to an optical nano-printing method of a pattern transfer technique for forming the structure of a very fine shape. <P>SOLUTION: In the stamper for optical inprints, it is made of a transparent substance having a transmittance not smaller than 50% to ultraviolet rays and it has recesses and protrusions in its principal surface. At least the top surface of each protrusion comprises an opaque portion having a transmittance not larger than 10% to ultraviolet rays. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nanoimprint transfer method in which a fine structure is formed on a substrate using an optical imprint method. The present invention relates to an optical imprint such as a semiconductor manufacturing process and other MEMS, biochips, optical devices, recording media, and display devices. It relates to using the printing process.

  In recent years, high precision of a photolithography apparatus has been promoted as a pattern transfer technique for realizing fine processing of a semiconductor integrated circuit. With the miniaturization of patterns, the exposure wavelength has been shortened, but the limit of the wavelength of the light source has been approached, and the lithography technology has also approached the limit. Therefore, in order to advance further miniaturization and higher accuracy, an electron beam drawing apparatus, which is a kind of charged particle beam apparatus, has been used in place of lithography technology.

  As a result, while miniaturization of the pattern is promoted, the electron beam lithography apparatus must be enlarged and a mechanism for controlling the mask position with higher accuracy is required. was there.

  For this reason, development of an imprint technique is being promoted as a new technique for forming a fine pattern at a low cost, which is disclosed in Patent Documents 1 to 3 listed below. In this method, a predetermined pattern is transferred by embossing a stamper having the same unevenness as the pattern to be formed on the substrate against the resist film layer formed on the surface of the substrate to be transferred. A method of transferring a pattern by irradiating ultraviolet rays using a curable resist is called a photoimprint method, and is considered suitable for transferring a fine pattern.

There has also been reported an attempt to improve light extraction efficiency from an LED by forming regular irregularities on the surface of the LED using an imprint method (Patent Document 4).
US Pat. No. 5,259,926 US Pat. No. 5,772,905 JP 2004-288845 A JP 2005-5679

  However, in the imprint process for forming a fine pattern, when the stamper and the resist are separated after pressing, there is a problem that the resist is partially peeled off together with the stamper due to pressure bonding or friction between the resist and the stamper. . For this reason, it has been difficult to peel the stamper pressed on the substrate from the substrate with high accuracy without breaking the fine irregularities formed on the substrate.

  In view of such a technical problem, the present invention provides a process of peeling a stamper from a substrate in an optical nanoprint method, which is a pattern transfer technique for forming a fine-shaped structure in a manufacturing process of a semiconductor device or the like. It is an object of the present invention to provide a stamper that can be performed with high accuracy and easily and a manufacturing method using the same.

  In order to solve the conventional problems, the optical imprinting stamper of the present invention is made of a transparent body having a transmittance of 50% or more with respect to ultraviolet rays, and the optical imprinting stamper having a concave portion and a convex portion on a main surface thereof, At least the outermost surface of the convex portion is an opaque portion having a transmittance of 10% or less with respect to ultraviolet rays.

  Thus, in the process of forming a pattern on the substrate, by applying the photoimprinting stamper to the ultraviolet curable resist applied on the substrate, the ultraviolet ray is irradiated only through the concave portion of the stamper, Although the curable resist is cured, ultraviolet rays are not irradiated through the convex portions of the stamper, and the ultraviolet curable resist immediately below the convex portions is not cured, so that the fine irregularities formed on the substrate are not destroyed. It is possible to peel the pressed stamper from the substrate with high accuracy and ease.

  Moreover, the optical imprint stamper of the present invention is characterized in that a main surface having the concave portion and the convex portion is sapphire or quartz.

  This makes it possible to form a stamper having high rigidity and transparency.

  The optical imprint stamper of the present invention is characterized in that the main surface is made of quartz and sapphire is bonded to the back surface.

  As a result, quartz can be finely processed more easily than sapphire, so even a stamper having a complicated shape that is difficult to produce with sapphire alone can be easily produced.

  The optical imprint stamper of the present invention is characterized in that a coating film made of any one of Ni, Cr, TiC, and TiN is formed on the surface of the convex portion.

  As a result, it is possible to form a stamper that is hard to wear even after repeated use and has high durability.

  The optical imprint stamper of the present invention is characterized in that the main surface is coated with porous alumina.

  As a result, a honeycomb body having regular cylindrical through-holes can be formed on the substrate relatively easily, so that a stamper for transferring a cylindrical regular pattern can be easily configured. it can.

The present invention also relates to a method for manufacturing a semiconductor substrate by an optical imprint method,
With one surface of any of the optical imprint stampers pressed against the ultraviolet curable resist applied on the semiconductor substrate, the other surface side of the optical imprint stamper is exposed to the ultraviolet curable resist. The ultraviolet curable resist is cured by irradiating with ultraviolet rays.

  This makes it possible to peel the stamper pressed on the substrate from the substrate with high accuracy and without breaking the fine irregularities formed on the substrate.

  In this way, the present invention enables the optical nanoprint method, which is a pattern transfer technique for forming a finely shaped structure in a semiconductor manufacturing process, to be pressed on the substrate without breaking the fine irregularities formed on the substrate. It is possible to easily and easily peel the stamper from the substrate. It should be noted that this effect can be further ensured by performing this process in a vacuum atmosphere. That is, when the stamper and the pattern transfer object are processed under atmospheric pressure, the resist is interposed between the stamper and the pattern transfer object, so that the distance between the stamper and the resist is removed when the stamper is peeled from the substrate. This is because the resist is likely to be peeled off in a vacuum state, but such a problem can be avoided by performing the treatment in a vacuum atmosphere.

  1st invention consists of a transparent body with the transmittance | permeability 50% or more with respect to an ultraviolet-ray, In the stamper for optical imprint which has a recessed part and a convex part in a main surface, the outermost surface of the said convex part is a transmittance | permeability with respect to an ultraviolet-ray. A stamper for optical imprinting, characterized by being an opaque portion of 10% or less.

  FIG. 1 shows an example of the stamper of the present invention. Concavities and convexities are formed on the surface of the stamper made of the transparent body 1 made of sapphire, the convex portion 2 is also made of the transparent body 1 made of sapphire, and the opaque portion 3 made of Ni is formed on the outermost surface of the convex portion 2. . By using this, in the process of forming a pattern on the substrate, as shown in FIG. 3, by applying the optical imprint stamper to the ultraviolet curable resist 8 applied on the substrate, the pressing 10 is applied to the stamper. Since the ultraviolet ray 9 is irradiated only through the concave portion of the stamper in the added state, the ultraviolet curable resist just under the concave portion is cured, but the ultraviolet ray is not irradiated through the convex portion 6 of the stamper and is cured under the convex portion 6. The mold resist is not cured. For this reason, when the stamper is separated from the substrate, the force applied to the fine irregularities formed on the substrate can be minimized, so that the stamper can be separated from the substrate without breaking the irregular shape. Is possible.

  On the other hand, when the conventional stamper for optical imprinting shown in FIG. 2, that is, a stamper which is entirely transparent and does not have an opaque portion, is used, the stamper transmits ultraviolet rays in the imprinting process shown in FIG. All the resist below is hardened. For this reason, when the stamper is pulled away from the substrate, the hardened irregularities are pulled by the stamper and the shape tends to collapse. This is because, when the UV curable resist is cured, there is a contraction of about 6%. Therefore, when the resist is cured even immediately below the convex portion 6 of the stamper, the convex portion 6 of the stamper becomes a resist due to the shrinkage of the resist. This is because the cured resist is pulled to the stamper side when being separated from the substrate. On the other hand, in the stamper of the present invention, the resist immediately below the convex portion 6 is not cured, and only the resist immediately below the concave portion of the stamper is cured, so the cured resists are independent from each other. The pinching force does not work. For this reason, it can be said that when the stamper of the present invention is used, the resist is not peeled off or the shape is not easily broken.

Table 1 shows the rate of occurrence of resist peeling when imprinting is actually performed using the imprinting stamper according to the present invention.

  No. in Table 1 1-3 are the experimental results by the stamper having the opaque part of the present invention. Quartz is used as the material of the transparent body 1 and Ni is used as the material of the opaque portion 3. The transmittance of the quartz having a thickness of 10 mm was about 86% with respect to the ultraviolet ray 9 having a wavelength of 320 nm, and the transmittance of the opaque portion 3 was almost zero.

  Each of the three pattern widths of 2 μm, 0.5 μm, and 0.1 μm shows the ratio of resist peeling. According to the present invention, it can be seen that the resist peeling is very small. On the other hand, No. 4 shows a case where quartz is used and the opaque portion 3 is not present. However, even when the pattern width is 0.5 μm, peeling of about 5.1% occurs, which indicates that there is a problem. No. 5 to 6 show the case where Pyrex (registered trademark) glass is used as the stamper material. Under the same irradiation conditions of ultraviolet rays 9 as 1 to 4, the resist was not cured and did not function as a stamper for photoimprinting. This is probably because the Pyrex (registered trademark) glass having a thickness of 10 mm has a transmittance of only about 17% with respect to the ultraviolet ray 9 at a wavelength of 320 nm.

  As described above, as the stamper of the present invention, the transmittance of the transparent portion 1 with respect to the ultraviolet ray 9 is at least 50% or more, and the transmittance of the ultraviolet ray 9 at least on the outermost surface of the convex portion 2 is 10% or less. desirable. This is because at least a difference in transmittance between the transparent body 1 and the opaque portion 3 is required to be at least 5 times or more in order to partially cure the ultraviolet curable resist and bring about the effects of the present invention. Because. If the difference in transmittance is 5 times or more, a partially cured portion and an uncured portion can be intentionally created, and the effects of the present invention can be brought about. Here, the ultraviolet region refers to a wavelength range of at least 300 to 400 nm.

  The second invention is an optical imprint stamper in which a main surface having the concave portion and the convex portion 9 is sapphire or quartz. This makes it possible to construct a stamper having high rigidity and transparency. No. in Table 1 7 is an experimental example according to the present invention using sapphire. 8 is a comparative example using Pyrex (registered trademark) glass. As explained above, Pyrex (registered trademark) glass has a very low UV transmittance, so the resist does not cure under the same UV irradiation conditions as when sapphire is used, and the resist peeling rate is compared. I couldn't.

  A third invention is an optical imprint stamper in which the main surface is made of quartz and sapphire is bonded to the back surface. Quartz is easier to finely process than sapphire, and this makes it possible to produce complex irregularities. In addition, since sapphire used for the back surface has high rigidity, deformation due to bending during pressing can be reduced compared to stampers made of other materials. No. in Table 1 9, No. 10 is a comparison of the amount of deflection when a pressure of 98 KPa is applied to a φ50 mm stamper. No. No. 9 is a case where 9 mm of sapphire and 1 mm of quartz are bonded together. Reference numeral 10 denotes the amount of deflection when 10 mm Pyrex (registered trademark) glass is used. In the present invention, the amount of deflection is about 1/5, which indicates that more accurate pattern transfer is possible. Here, the case where the stamper is manufactured by bonding is taken as an example, but it is also possible to directly join quartz and sapphire without using an adhesive.

  The fourth invention is an optical imprint stamper in which a coating film made of any one of Ni, Cr, TiC, and TiN is formed on the surface of the convex portion 9. Thereby, even if the opaque part 3 of the convex part 9 is used repeatedly, it is hard to be worn, and a highly durable stamper can be constituted. As the material of the opaque part 3, the No. 1 in Table 1 was used. No. 11 and Ni. 12 shows film peeling of the opaque portion 3 when Al is used. In each case, the imprint was repeated 100 times and compared, and no film peeling occurred in Ni, but in the case of Al, film peeling occurred 30 times and there was no durability.

  A fifth invention is a stamper for optical imprint, wherein the main surface is coated with porous alumina. This is a stamper for optical imprinting in which a porous alumina film is formed on the opaque portion 3 of the convex portion 9 by an anodic oxidation method, and a cylindrical hole is penetrated to the transparent body 1.

  Thereby, a stamper for transferring a cylindrical regular pattern can be easily configured. Specifically, an aluminum film having regular through-holes can be formed by depositing an aluminum film on a sapphire or quartz substrate by an about 2 μm sputtering method and then anodizing the aluminum. No. in Table 1 No. 13 The stamper produced in this way was 14 shows a comparative example of occurrence of film peeling when Al is used for the opaque portion 3. In the case of anodized alumina, film peeling did not occur even after imprinting 100 times, but in the case of Al, film peeling occurred 30 times and there was no durability.

  According to a sixth aspect of the present invention, ultraviolet curing is performed from the other surface side of the optical imprinting stamper while one surface of the optical imprinting stamper according to the present invention is pressed against the ultraviolet curing resist applied on the semiconductor substrate. This is a method for manufacturing a light-emitting device in which an ultraviolet ray 9 is irradiated to a mold resist and the ultraviolet curable resist is cured. According to the present invention, a stamper pressed on a substrate can be easily and accurately peeled off from the substrate without breaking fine irregularities formed on the substrate. No. in Table 1 15 shows peeling of the concavo-convex pattern resist produced using the stamper of the present invention, and no peeling occurred. No. No. 16 shows the peeling of the resist of the concavo-convex pattern produced using the conventional stamper which does not have the opaque part 3, but peeling of 5% or more occurred. Further, FIG. 5 shows a structural diagram showing an example of an LED having irregularities on the emission side created by this method. The light extraction efficiency to the outside of the LED manufactured with such a configuration was improved about twice as compared with the conventional example.

  Examples of the present invention will be described below. Note that the present invention is not limited to the embodiments.

Example 1
FIG. 1 shows an imprint stamper according to the present invention. This imprint stamper was produced by the following procedure. First, a plate-like sapphire having a predetermined size was pulled up by the EFG method, and then processed into a predetermined size and thickness by grinding using a grindstone. Next, both surfaces were mirror-finished using diamond abrasive grains as an abrasive. Next, cross polishing was further performed on both sides using colloidal silica to produce a transparent sapphire substrate 1.

  Next, a resist was applied to one side of the transparent sapphire substrate 1, and a predetermined mask pattern was formed by an electron beam drawing method. A metal film was formed on the substrate on which the mask pattern was formed by vapor-depositing at least one of Ti, Cr, and Ni to a predetermined thickness by sputtering or the like. Thereafter, the mask pattern of the resist was removed by washing with acetone, the metal film was lifted off, and a metal film pattern 3 was formed on the sapphire substrate. Using the metal film thus formed on the sapphire substrate as a mask, the sapphire substrate was further dry-etched with a fluorine-based or chlorine-based gas to form a sapphire pattern. When dry etching of the sapphire substrate is performed in this manner, the sapphire substrate is etched to form recesses, but at the same time, the metal film as a mask material is also etched, and the metal film becomes thinner with time. In addition, all the metal film is removed. However, in the present invention, by adjusting the thickness of the metal film and the dry etching time optimally, a predetermined recess is formed in the sapphire substrate, and at the same time, the metal film 3 remains on the surface of the protrusion 2. I was in a state. At this time, when the ultraviolet transmittance was measured using a test piece having the same thickness as that of the metal film remaining on the convex portion 2, it was 0%, which was 10% or less of the target.

  The sapphire substrate thus produced was bonded to a transparent quartz substrate having a predetermined shape with a transparent adhesive to produce an optical imprint stamper. At this time, when the ultraviolet transmittance of a test piece in which a transparent sapphire substrate on which a pattern was not formed and a transparent quartz substrate were bonded with a transparent adhesive was measured, it was about 80%, which was 50% or more of the target. .

  Table 1 shows a stamper according to the present invention and a comparative example. No. in Table 1 1-3 are the experimental results by the stamper having the opaque portion 3 of the present invention. Quartz is used as the material of the transparent body 1 and Ni is used as the material of the opaque portion 3. The transmittance of quartz having a thickness of 10 mm was about 86% with respect to ultraviolet rays having a wavelength of 320 nm, and the transmittance of the opaque portion 3 was almost zero. The ratio of resist peeling is shown for three types of pattern widths of 2 μm, 0.5 μm, and 0.1 μm, respectively, but it can be seen that according to the present invention, resist peeling is very small. On the other hand, No. 4 shows the case where quartz is used and the opaque portion 3 is not present. About 5.1% of peeling occurs even when the pattern width is 0.5 μm, which indicates that there is a problem. No. 5 to 6 show the case where Pyrex (registered trademark) glass is used as the stamper material. Under the same irradiation conditions of ultraviolet rays 9 as 1 to 4, the resist was not cured and did not function as a stamper for photoimprinting. This is probably because the Pyrex (registered trademark) glass having a thickness of 10 mm has a transmittance of only about 17% with respect to the ultraviolet ray 9 at a wavelength of 320 nm, and therefore the irradiation amount of the ultraviolet ray 9 is insufficient.

(Example 2)
Next, a process for forming a pattern on a semiconductor substrate using the optical imprint stamper of the present invention will be described. First, in a process for manufacturing a semiconductor element using a silicon substrate, an ultraviolet curable resin was uniformly applied to a predetermined silicon substrate.

  Next, the optical imprinting stamper according to the present invention was pressed against the substrate coated with the ultraviolet curable resin in a vacuum atmosphere, and the ultraviolet curable resin was deformed following the pattern shape. The pressing pressure was 110 kgf / cm2. Moreover, since this process was performed in a vacuum, there was no problem that bubbles in the atmosphere were taken in the resin and the pattern deteriorated.

  Next, ultraviolet rays 9 were irradiated from the back surface of the optical imprint stamper according to the present invention, and the ultraviolet curable resin deformed following the pattern shape was cured. The irradiated ultraviolet ray 9 had a wavelength of 300 nm to 400 nm, and the irradiation condition was 100 J / cm2. Thereafter, the stamper for optical imprinting was slowly pulled away from the silicon substrate onto which the pattern was transferred in a vacuum. At this time, since the surface of the convex portion 2 of the optical imprint stamper is opaque to ultraviolet rays, the resin immediately below the convex portion 2 is not cured, and the pattern is pulled by the stamper in the step of separating the stamper. The film was not peeled off and transferred accurately without breaking the fine pattern.

(Example 3)
Next, an example in which the columnar convex portion 2 is formed on the LED surface using the imprint stamper of the present invention will be described. FIG. 5 is a schematic view of a product in which columnar convex portions 2 are formed on the LED surface using the imprint stamper of the present invention. In this example, a cylindrical convex portion 2 was produced on the surface of a blue LED having a wavelength of 450 nm using the imprint stamper according to the fourth invention.

  In general, a blue LED has a GaN buffer layer and an n-type GaN contact layer 12, an n-type AlGaN cladding layer 14, a GaN-based semiconductor light emitting layer (MQW structure) 15, a p-type AlGaN cladding layer 16, p on a sapphire substrate. The type GaN contact layers 17 are sequentially stacked and grown, and a transparent electrode 18 is formed on the outermost surface. Furthermore, after removing a part by etching, the n-type electrode 13 and the p-type electrode 19 are formed.

  In this way, a photocurable resin is applied to the surface on the emission side of the substrate on which the gallium nitride blue LED is formed, and imprinting is performed using the stamper according to the fourth aspect of the invention. Part 2 was formed. The diameter of one side of the convex part 2 of the cylinder thus produced was about 1 μm on average, and the average distance between the cylinders was about 1.0 μm. In this way, since the plurality of columnar convex portions 2 are formed on the light emitting side surface of the LED, the light emitted from the LED is diffracted forward by the columnar convex portions 2, and the light emitting device surface It was possible to prevent total reflection, and as a result, the light extraction efficiency could be improved. As a result, it was possible to double the light emission intensity as compared with the conventional LED having a structure with no unevenness on the emission side.

It is sectional drawing which shows the stamper for optical imprint which has an opaque part in the convex part of this invention. It is sectional drawing which shows the comparative example which does not have an opaque part in a convex part. It is sectional drawing which shows the process of imprinting using the stamper for optical imprinting by this invention. It is sectional drawing which shows the process of imprinting using the stamper for optical imprint which does not have an opaque part in a recessed part. It is sectional drawing which shows the thing which formed the periodic convex part in LED using this invention.

Explanation of symbols

1: Transparent body 2: Convex part 3: Opaque part 4: Semiconductor substrate 5: Opaque part 6: Convex part 7: Transparent body 8: Ultraviolet curing resist 9: Ultraviolet light 10: Press 11: Sapphire substrate 12: n-type GaN contact Layer 13: n-type electrode 14: n-type AlGaN cladding layer 15: GaN-based semiconductor light emitting layer (MQW structure)
16: p-type AlGaN cladding layer 17: p-type GaN contact layer 18: p-type transparent electrode 19: p-type electrode 20: convex portion

Claims (6)

  In an optical imprint stamper made of a transparent body having a transmittance of 50% or more with respect to ultraviolet rays and having a concave portion and a convex portion on the main surface, at least the outermost surface of the convex portion is opaque with a transmittance of 10% or less with respect to ultraviolet rays. A stamper for optical imprinting, characterized by being a part.   2. The optical imprint stamper according to claim 1, wherein a main surface having the concave portion and the convex portion is sapphire or quartz.   3. The optical imprint stamper according to claim 1, wherein the main surface is made of quartz and sapphire is bonded to the back surface.   4. The optical imprint stamper according to claim 1, wherein a coating film made of any one of Ni, Cr, TiC, and TiN is formed on the surface of the convex portion.   The optical imprint stamper according to any one of claims 1 to 3, wherein the main surface is coated with porous alumina.   From the other surface side of the optical imprinting stamper, in a state where one surface of the optical imprinting stamper according to any one of claims 1 to 5 is pressed against an ultraviolet curable resist applied on a semiconductor substrate. A method for manufacturing a light emitting device, comprising irradiating an ultraviolet curable resist with ultraviolet rays to cure the ultraviolet curable resist.

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