JP2006111491A - Method for manufacturing glass micro lens array and glass micro lens array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass micro lens array, by which the glass micro lens array excellent in durability and translucency can be manufactured in a large quantity at a low cost, and to provide glass micro lenses obtained by using the method. <P>SOLUTION: The method for manufacturing the glass micro lenses comprises preparing a heated glass base material 12 and then pressing the glass base material 12 by a high temperature press molding method using a mold 1 made of glassy carbon so as to form many micro lenses in an array state on the surface of the glass base material 12. The glass micro lenses obtained by the method are also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a glass microlens array manufacturing method, a glass microlens array, and in particular, a glass microlens array manufacturing method in which a glass substrate is pressed by a high temperature press molding method using a glassy carbon mold, The present invention relates to a glass microlens array.

  A microlens array is used for condensing light onto a liquid crystal panel such as a projector. There are two types of microlens arrays currently used, one made of resin and one using glass.

  Resins have good processability and are inexpensive, but have problems with durability and light transmission, while glass has poor processability and is therefore expensive, but has excellent durability and light transmission.

  In particular, a silica glass microlens array is very attractive for a microlens array that requires high accuracy because it is resistant to high temperatures and has an extremely small coefficient of thermal expansion. In particular, it is essential to use silica glass when the projector manufacturing process includes a process of being exposed to a high temperature of 1000 ° C. or higher.

  In general, for manufacturing a glass microlens array, etching using a semiconductor manufacturing technique is standardly used, and a pressing technique for glass is well known. Furthermore, it is also known to use glassy carbon as a material of a mold used in a high-temperature glass press.

  In particular, a method using dry etching, which is a semiconductor processing technique (Patent Document 1), and a method using electric discharge machining and machining have been proposed for microfabrication of a glassy carbon mold used for pressing silica glass. .

  However, in the glass microlens array manufacturing method described in Patent Document 1, since silica glass is chemically stable, wet etching and dry etching require a long process, and further, a metal mask, a resist material, etc. Special mask material is required, the process is complicated, and the cost and environmental load are very high.

  Further, when machining directly by machining, since glass is a brittle material, chipping is likely to occur, and since the amount of cutting cannot be obtained, the machining time becomes very long, which is not realistic.

  Further, in the case of fine processing by high-temperature pressing of silica glass, how to process glassy carbon to be a molding die has been a big problem. Among the above prior arts, accuracy and miniaturization are problems in machining, and accuracy, miniaturization, and chipping are problems in electric discharge machining, and it is very difficult to manufacture a target microlens array.

  This is because glassy carbon is a brittle material and is very vulnerable to thermal shock, so that chipping, cracking and chipping are likely to occur.

  Therefore, a method for efficiently processing glassy carbon with high accuracy has been demanded. In addition, dry etching is an ideal method for microfabrication of glassy carbon, but in reality, there are many problems such as extremely rough surfaces during etching and uneven etching depth. The processed surface could not be transferred and used as it was.

  This rough surface during etching is due to the fact that glassy carbon is not strictly a homogeneous material and is essentially different from single crystal silicon or very homogeneous CVD polycrystalline silicon used in semiconductors. It is.

Further, glassy carbon is a form of carbon, and has essentially the same properties as those causing organic contamination. Therefore, the etching is greatly affected by organic substances on the surface. This is very different from silicon, which can easily remove organic substances by ashing.
JP 2004-18282 A

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a method for producing a glass microlens array capable of mass-producing a glass microlens array excellent in durability and translucency at low cost. To do.

  Another object of the present invention is to provide an inexpensive glass microlens array having excellent durability and translucency.

  In order to produce a glassy carbon mold that can mold a glass microlens array excellent in durability and translucency, the present inventors tried various processing methods for glassy carbon. By using dry etching, a method that can control the etching depth uniformly over a relatively wide range is found, and the object to be molded does not come into contact with the etching surface of the hole of the mold so that the roughness is relatively large. A method for obtaining a smooth lens shape without being affected by the etched surface has been found, and the present invention has been completed.

  That is, in order to achieve the above object, the method for producing a glass microlens according to the present invention provides a heated glass substrate, and the glass substrate is subjected to high-temperature press molding using a glassy carbon mold. A large number of microlenses are arranged on the surface and pressed by the method.

  Preferably, the glassy carbon mold is processed by dry etching.

  Preferably, the dry etching is performed using an Al pattern.

  Preferably, removal of organic contamination on the surface after forming the Al pattern is performed by washing with an organic solvent.

  The dry etching uses any one of an oxidizing atmosphere combustion method, an inductively coupled plasma etching method, a reactive ion etching method, and a chemical dry etching method.

  Preferably, the dry etching includes an oxygen gas having an atmosphere gas of 10 to 100% by volume.

  Preferably, the porosity contained in the glassy carbon is 0% by volume.

  Preferably, the glassy carbon controls the depth of the hole shape and the press pressure so that the object pressed by the press does not contact the bottom of the hole shape formed by dry etching. .

  Preferably, the glass used for the glass microlens array is silica glass.

  Preferably, the total concentration of Na, K, and Ca contained in the glassy carbon is 1 ppm or less.

  Preferably, the silica glass has a total metal contamination concentration excluding Al at a surface layer of 50 μm of 10 ppm or less.

  The glass microlens array according to the present invention is characterized by being molded by a high-temperature press molding method using a glassy carbon molding die.

  According to the method for producing a glass microlens array according to the present invention, it is possible to provide a method for producing a glass microlens array capable of mass-producing a glass microlens array having excellent durability and translucency at low cost. .

  In addition, according to the glass microlens array of the present invention, it is possible to provide a glass microlens array that is inexpensive, excellent in durability and translucency.

  Hereinafter, an embodiment of a method for producing a glass microlens array according to the present invention will be described with reference to the accompanying drawings.

  First, a method for producing a mold that becomes a master when used in the production (transfer) of a glass microlens array according to the present invention will be described.

  FIG. 1 is a flow chart for manufacturing a master mold.

  As shown in FIG. 1, first, the surface of a flat glassy carbon material 2 serving as a base material is mirror-finished and sufficiently cleaned by acid cleaning, organic cleaning, or the like (S1).

  The glassy carbon material preferably has a porosity of 0% in consideration of shape processability and uniform etching properties. When silica glass is used for the base material of the glass microlens array, it is necessary to suppress the occurrence of devitrification (crystallization of silica glass) due to impurities because the press temperature requires a high temperature of 1300 ° C. or higher. For this reason, the concentration of impurities contained in the glassy carbon is preferably kept low, and the total concentration of at least Na, K, and Ca is preferably 1 ppm or less. In addition, since other impurities also have an effect of promoting the reaction between silica glass and carbon, it is necessary to perform sufficient washing, and the total concentration of metal contamination concentration excluding Al at the surface layer of silica glass of 50 μm is 10 ppm or less. In addition, the ash content of the glassy carbon is preferably 2 ppm or less.

  Next, Al3 is vapor-deposited on the processing surface by vacuum vapor deposition (S2).

  Al as a mask material is suitable because it has high adhesion to the base material and good workability and is suitable for fine pattern production, and is inexpensive and economical. However, the mask material is limited to this. It is not something.

  Further, a photoresist material 4 is applied on the Al3 surface (S3).

  Then, the resist pattern is exposed (S4) using the mask 5 and the projection lens 6 so that Al in the portion to become the microlens can be etched, and the unmasked photoresist material 4 is melted by development (S5). The Al portion not masked with the material 4 is wet-etched with acid (S6).

  The detailed conditions of the above process are in accordance with the Al wiring pattern forming process in the normal semiconductor IC manufacturing process.

  The photoresist material 4 is peeled off (S7).

  The organic substance is removed and washed (S8).

  If the organic contamination 5 remains on the surface, etching unevenness occurs in the subsequent dry etching, and the etching depth varies significantly. Therefore, the surface is thoroughly cleaned using a cleaning organic solvent, and then sufficiently rinsed with pure water. To do. As the cleaning liquid, acetone, isopropyl alcohol, and commercially available organic cleaning agents for removing organic substances can be used, but those containing a surfactant that can also be expected to have a particle removing effect are more preferable. Although it is effective to use ultrasonic waves at the time of cleaning, it is necessary to pay attention to the output and the like because it leads to peeling of the Al mask. At this time, acid / alkali cleaning that attacks Al cannot be used, but this is not the case when Al is not used for the mask (for example, using Au, Cr, Pt).

  This organic substance removal cleaning process is a pre-process that is processed by dry etching, and it completely removes organic contaminants on the glassy carbon surface that forms the mold, thereby improving the uniformity of the etching depth. When the glass is pressed, the shape of the hole and the pressing pressure can be controlled so that the object to be molded does not come into contact with the etched surface of the surface of the hole.

  Further, the glassy carbon other than the portion masked with Al is etched by dry etching to form the hole 6 (S9).

This etching is preferably a highly isotropic method, and an inductively coupled plasma etching (IPC) method, a reactive ion etching (RIE) method, or a chemical dry etching (CDE) method is preferable. The reaction gas used for dry etching preferably contains 10 to 100% by volume of O ₂ . Glassy carbon can be processed efficiently and with high accuracy by dry etching.

  Finally, the remaining Al mask is removed by acid etching and washed sufficiently to obtain a glassy carbon mold 1 (S10).

  Next, a manufacturing method (transfer molding) of the glass microlens array using the above mold will be described.

  FIG. 2 is a manufacturing flowchart of the glass microlens array according to the present invention.

  The glassy carbon molding die 1 is fixed to the lower punch 22 of the press 21, and a silica glass base material, for example, a flat substrate 12, which is a transfer object, is further placed thereon (S <b> 11).

  Thereafter, heating by the heating device 23 is started, and after confirming that the predetermined temperature has been reached, the upper punch 24 is lowered and the silica glass substrate 12 is pressed against the mold 1, and the shape of the hole 6 is transferred and molded. (S12) A glass microlens array 11 on which a large number of microlenses 13 are formed is obtained (S13).

  In S12, it is most important to adjust the pressing conditions according to the shape of the mold (hole depth) so that the object to be molded does not contact the etched surface of the surface of the hole 6. Is preferred. As a result, even if the surface of the mold is very rough due to etching and etching unevenness is produced, the processing surface of the glass microlens array is not affected, and a low-cost and high-performance glass microlens array is manufactured. Is possible.

  As a glass material, silica glass is very useful for a glass microlens array that requires high accuracy because it is resistant to high temperatures and has an extremely small coefficient of thermal expansion.

  The heating device 23 may be any of a resistance heating device using a metal or carbon resistor, a lamp heating device, or an induction heating device, but it is preferable to use a lamp heating device from the viewpoint of productivity.

  The press atmosphere must be an inert atmosphere, and the temperature should be such that the viscosity of the glass is 9.5 to 8.5 poise. Considering the reaction between the transferability and the mold, 8.8 to 9.2 poise. The degree is preferred.

  According to the method for manufacturing a glass microlens array according to the present invention, by using a dry die for processing a glassy carbon material, and using a mold manufactured using a high-precision, high-density microfabrication technique. Further, a glass microlens array excellent in durability and translucency can be manufactured at low cost and with low environmental load.

  As shown in FIGS. 3 and 4, a glass microlens array 11 manufactured by the glass microlens array transfer molding method according to the present invention using the mold as described above has a square silica glass substrate 12. And a large number of microlenses 13 arranged on the surface 12a of the silica glass substrate 12. The thickness of the silica glass substrate 12 is, for example, several tens of μm to several mm, and the height of the microlens 3 is several μm to several hundreds of μm.

  According to the glass microlens array of the present invention, an inexpensive glass microlens array having excellent durability and translucency is realized.

  Test 1: On the surface of glassy carbon that has been mirror-polished on one side using diamond abrasive grains, Al is used as a mask, □ 7 μm holes with a depth of 4 μm are processed at a pitch of 12 μm, and a glass microlens array A mold was formed. At the time of forming the mold, a cleaning agent (Clean Through LC841 manufactured by Kao Corporation) was used for cleaning before dry etching, and an ICP etcher was used for dry etching. The etching gas used was 100% oxygen by volume.

This mold was pressed against the surface of a silica glass plate mirror-finished in an inert atmosphere at 1450 ° C. with a pressure of 1 kN / cm ² so that the molded body did not contact the etched surface of the hole surface.

  As a result, a convex lens shape having a height of 3.5 μm was obtained.

Test 2: A silica glass plate was prepared in the same manner as in Test 1 except that a mold similar to Test 1 was prepared except that the hole size was □ 9 μm, and the pressure was 0.5 kN / cm ^2. The molded body was pressed against the etched surface of the hole so as not to contact the etched surface of the hole surface.

  As a result, a convex lens shape having a height of 3.5 μm was obtained.

The manufacturing flowchart of the shaping | molding die used for the glass-made microlens array which concerns on this invention. The manufacturing flowchart of the glass-made microlens array which concerns on this invention. The top view of the glass-made microlens array which concerns on this invention. The side view of the glass microlens array based on this invention.

Explanation of symbols

1 Glassy carbon mold 11 Glass microlens array 12 Silica glass substrate 13 Microlens 21 Press 22 Lower punch 23 Heating device 24 Upper punch

Claims (22)

A glass characterized in that a heated glass substrate is prepared, the glass substrate is pressed by a high-temperature press molding method using a glassy carbon mold, and a large number of microlenses are arranged on the surface thereof. Manufacturing method of microlens made. The method for manufacturing a glass microlens array according to claim 1, wherein the glassy carbon mold is processed by dry etching. The method of manufacturing a glass microlens array according to claim 2, wherein the dry etching is performed using an Al pattern. 4. The method for producing a glass microlens array according to claim 3, wherein the removal of organic contaminants on the surface after forming the Al pattern is performed by washing with an organic solvent. The glass according to any one of claims 2 to 4, wherein the dry etching uses any one of an oxidizing atmosphere combustion method, an inductively coupled plasma etching method, a reactive ion etching method, and a chemical dry etching method. A manufacturing method of a manufactured microlens array. 6. The glass microlens array according to claim 2, wherein the dry etching includes 10 to 100% by volume of oxygen gas. The method for producing a glass microlens array according to any one of claims 1 to 6, wherein the porosity contained in the glassy carbon is 0% by volume. The glassy carbon is characterized by controlling the depth of the hole shape and the press pressure so that the object pressed by the press does not contact the bottom of the hole shape formed by dry etching. Item 8. A method for producing a glass microlens array according to any one of Items 2 to 7. 9. The method for producing a glass microlens array according to claim 1, wherein the glass used in the glass microlens array is silica glass. The method for producing a glass microlens array according to any one of claims 1 to 9, wherein the total concentration of Na, K, and Ca contained in the glassy carbon is 1 ppm or less. 10. The method for producing a glass microlens array according to claim 9, wherein the silica glass has a total metal contamination concentration excluding Al at a surface layer of 50 [mu] m of 10 ppm or less. A glass microlens array formed by a high-temperature press molding method using a glassy carbon mold. 13. The glass microlens array according to claim 12, wherein the glassy carbon mold is processed by dry etching. The glass microlens array according to claim 13, wherein the dry etching is performed using an Al pattern. 15. The glass microlens array according to claim 14, wherein the removal of organic contamination on the surface after forming the Al pattern is performed by cleaning with an organic solvent. The glass according to any one of claims 13 to 15, wherein the dry etching uses any one of an oxidizing atmosphere combustion method, an inductively coupled plasma etching method, a reactive ion etching method, and a chemical dry etching method. Made micro lens array. The glass microlens array according to any one of claims 13 to 16, wherein the dry etching includes an oxygen gas having an atmosphere gas of 10 to 100% by volume. The glass microlens array according to any one of claims 12 to 17, wherein a porosity contained in the glassy carbon is 0% by volume. The glassy carbon is characterized by controlling the depth of the hole shape and the press pressure so that the object pressed by the press does not contact the bottom of the hole shape formed by dry etching. Item 19. The glass microlens array according to any one of Items 13 to 18. The glass microlens array according to any one of claims 12 to 19, wherein the glass used for the microlens array is silica glass. 21. The glass microlens array according to claim 12, wherein a total concentration of Na, K, and Ca contained in the glassy carbon is 1 ppm or less. 21. The glass microlens array according to claim 20, wherein the silica glass has a total metal contamination concentration excluding Al at a surface layer of 50 [mu] m of 10 ppm or less.

Images