TWI470278B - Microlenses fabrication - Google Patents

Description

Microlens structure manufacturing method

The present invention relates to a method of fabricating a microlens structure, and more particularly to a method of fabricating a microlens structure using ion exchange.

In addition to being applied to general mechanical components, optical components are often integrated into high-tech products such as semiconductors or microelectronics. With the advancement of electronic components, the miniaturization of components has become an inevitable trend in the development of science and technology. In order to better match optical components with electronic components, many micro-optical components have emerged, such as composite microlenses or microlens arrays. Micro lens Array) and so on. Among them, the microlens array can perform array focusing function in a micron-scale size, and is widely used in microelectronic products. As a method of manufacturing the microlens array, techniques such as a thermal remelting method and an ion exchange method are known.

The hot remelting method is the most common manufacturing method of the microlens array, and the method is to set a plurality of photoresists on a glass substrate, and use the lithography technology to form the photoresist into a circular array, and then the photoresist The microlens array is formed by heating to a melting point of the photoresist to melt the photoresist. However, the thermal remelting method has difficulty in controlling the shape of the microlens, and it is impossible to control the shape of the microlens at will, and it is more difficult to control the lens depth and the radius of curvature of the microlens array.

The ion exchange method is divided into several methods, one of which is a wet ion exchange method using a molten salt. The molten salt may be selected from AgNO ₃ or KNO ₃ containing Ag ions or K ions, and the glass substrate to be ion-exchanged is placed in the molten salt solution, and the Na ions in the glass and the molten salt are thermally diffused. The Ag ions or K ions exchange with each other and form a region of higher refractive index on the surface of the glass. However, the microlens is manufactured by means of molten salt and thermal diffusion. When the glass substrate is easily eroded by the molten salt, the surface of the glass substrate is easily damaged, which affects the concentrating effect of the microlens array.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a method of fabricating a microlens structure that can be easily controlled during fabrication of the microlens array.

A secondary object of the present invention is to provide a method of fabricating a microlens structure that reduces surface damage caused by the microlens array during the manufacturing process.

In order to achieve the above object, the microlens structure manufacturing method of the present invention comprises: a pre-step, forming a silver film on the surface of a glass substrate by electroplating; and a photoresist setting step of setting at least one photoresist Laying on the surface of the silver film; an etching step of etching the silver film not between the glass substrate and the photoresist layer; and a photoresist removing step of removing the photoresist layer on the surface of the silver film; An ion exchange step is to establish an electric field bias through the silver film and the glass substrate, so that silver ions of the silver film are ion-exchanged with sodium ions of the glass substrate to form a silver ion layer microlens in the glass substrate. .

In the microlens structure manufacturing method of the present invention, the working temperature of the ion exchange step is between 300 and 500 ° C.

In the microlens structure manufacturing method of the present invention, the electric field bias of the ion exchange step is between 300 and 857 V/mm.

The microlens structure manufacturing method of the present invention, wherein the ion exchange step has a working time of 50 to 100 minutes.

In the microlens structure manufacturing method of the present invention, the silver film has a thickness ranging from 2 to 10 μm.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

Referring to FIG. 1 , the microlens structure manufacturing method of the present invention comprises a pre-step S1, a photoresist setting step S2, an etching step S3, a photoresist removing step S4, and an ion exchange step S5. In order to make the description of the present invention more detailed, please refer to Figures 2 to 8 and compare the steps of the present invention.

In the pre-step S1, a silver thin film 2 is formed on the surface of a glass substrate 1 by electroplating. As shown in FIGS. 2 and 3, in the present embodiment, the glass substrate 1 is selected, and a silver film 2 is plated by electroplating on the surface of the glass substrate 1 on which a microlens structure is to be formed. The composition of the glass substrate 1 contains sodium (Na), and the content of the nanometer is preferably 4 to 9.5% of the total composition of the glass substrate. The thickness of the silver film 2 can be increased or decreased according to the thickness of the microlens that the user wants to form. When a thick microlens is to be produced, a thick silver film 2 can be plated, if a thin microlens is to be produced. A thin silver film 2 can be plated, wherein the silver film 2 can be controlled to have a thickness of 2 to 10 μm by electroplating. More specifically, for different applications, it may be necessary to form a microlens structure having a larger thickness, and a thicker silver film 2 may be formed by electroplating, so that the microlens has a better focusing effect.

The production of silver film can be achieved by electroplating, and the method of electroplating has the following advantages compared to the general vacuum coating technique:

1. High coating speed: The rate of silver film produced by electron beam evaporation is generally lower than 10 nm/min. If the silver layer of 0.7-1.2 micron is obtained by electroplating silver in 5-8 minutes, the process time can be saved.

2. Low equipment cost: The electroplated machine is much cheaper than the electron beam evaporation machine.

3. Low process cost: The electroplating process consumes a lot less power than the electron beam evaporation method, and the electron beam evaporation method wastes more silver during the production process.

4. The thickness of the silver film: The thickness of the silver film by electron beam evaporation is generally less than 1 μm, but the plating process can easily break through this limitation.

5. Low process temperature: The process temperature of electroplating is about 60 ° C or less, and the substrate is subjected to high temperature during the electron beam evaporation process. If the lift-off process is to be used, the low temperature process stability is high.

The photoresist setting step S2 is to provide at least one photoresist layer 3 on the surface of the silver thin film 2. As shown in FIG. 4, the photoresist layer 3 can be disposed on the surface of the silver film 2, and the arrangement is the position where the glass substrate 1 is to form a microlens array, and the photoresist layer 3 is used to protect the surface. The silver film 2 is disposed at the place where the silver film 2 at the setting is prevented from being unnecessarily etched, whereby the silver film 2 can be smoothly ion-exchanged with the glass substrate 1.

In the etching step S3, the silver thin film 2 which is not located between the glass substrate 1 and the photoresist layer 3 is etched. As shown in Figure 5, due to the silver film 2 For ion exchange with the glass substrate 1 to form the microlens, it is necessary to remove the unnecessary silver film 2 on the glass substrate 1 completely covering the silver film 2, so that the silver film 2 and the glass When the substrate 1 is ion-exchanged, it can occur only in the region where the microlens is to be generated.

The photoresist removal step S4 removes the photoresist layer 3 on the surface of the silver film 2. As shown in FIG. 6, in order to prevent the photoresist layer 3 from affecting the ion exchange between the silver thin film 2 and the glass substrate 1, the photoresist layer 3 must be removed before ion exchange.

In the ion exchange step S5, an electric field is biased through the silver film 2 and the glass substrate 1, and silver ions of the silver film 2 are ion-exchanged with sodium ions of the glass substrate 1 to form in the glass substrate 1. One of the silver ion layers is a microlens array 4.

Referring to Figures 7 and 8, in a preferred embodiment of the present invention, the glass substrate 1 on which the silver film 2 has been plated is placed in a heater 5 so that the glass substrate 1 can be subjected to a high temperature environment. The ion exchange is performed, and the electric field is biased to the glass substrate 1 and the silver thin film 2 by a power supply 6. The power supply device 6 is preferably disposed by connecting a positive electrode 61 to one end of the glass substrate 1 coated with the silver film 2, and then connecting a negative electrode 62 to the glass substrate 1 and not being plated with one end of the silver film 2. A high electric field region generated by the positive electrode 61 is located at the silver thin film 2, and the electric field intensity is gradually weakened along a region of the glass substrate 1 to be ion-exchanged, and the glass substrate 1 is connected to one end of the negative electrode, and A low electric field region is formed at the negative electrode.

When the silver film 2 is in a high temperature and high electric field environment, the silver film 2 can dissociate a silver ion and drive the silver ions into the glass substrate 1 by driving the electric field, and then one of the sodium ions is transferred thereto. Pushing at a low electric field, making The sodium ions are pushed out to the glass substrate 1 at a low electric field for the purpose of ion exchange, and the microlens array 4 of the silver ion layer is formed at one end of the ion exchange of the glass substrate 1.

The high temperature environment provided by the heater 5 is preferably between 300 and 500 ° C in the embodiment, and the electric field bias provided by the power supply 6 is preferably between 300 and 857 V / Between mm, and the ion exchange time is preferably from 50 to 100 minutes. In addition, since the thickness of the microlens array 4 has a positive correlation with the thickness of the silver thin film 2, the relatively required silver thin film can be plated during electroplating according to the lens thickness of the microlens array 4 to be generated. 2. Once the silver film 2 is depleted or the driving electric field is turned off, the ion exchange process can also be terminated, so that the total amount of ion exchange is easily controlled, and the microlens array 4 can be formed to meet the demand. Further, when the glass substrate 1 is a material which is easily attacked by molten salt such as phosphate, the ion exchange method of the present invention does not require the glass substrate 1 to be placed in a molten salt, and the glass substrate of a specific material can be avoided. 1 The surface is eroded to reduce the damage of the lens itself to enhance the concentrating effect.

In the microlens structure manufacturing method of the present invention, the thickness of the silver film and the electric field intensity can be used to control the formation of the microlens, and the effect of forming the radius of curvature and the depth of the lens can be easily controlled.

The microlens structure manufacturing method of the invention can avoid the surface damage caused by the glass substrate being placed in the molten salt, and has the effect of improving the light collecting effect.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

〔this invention〕

1‧‧‧ glass substrate

2‧‧‧Silver film

3‧‧‧ photoresist layer

4‧‧‧Microlens array

5‧‧‧heater

6‧‧‧Power supply

61‧‧‧ positive electrode

62‧‧‧negative electrode

S1‧‧‧Pre-steps

S2‧‧‧ photoresist setting steps

S3‧‧‧ etching step

S4‧‧‧ photoresist removal step

S5‧‧‧Ion exchange step

Fig. 1 is a view showing the steps of a method for manufacturing a microlens structure of the present invention.

Figure 2: Schematic diagram of the pre-steps of the present invention.

Figure 3: Schematic diagram of the pre-steps of the present invention.

Figure 4 is a schematic view showing the steps of setting the photoresist of the present invention.

Figure 5: Schematic diagram of the etching step of the present invention.

Figure 6 is a schematic view showing the step of removing the photoresist of the present invention.

Figure 7: Schematic diagram of the ion exchange step of the present invention.

Figure 8: Schematic diagram of the ion exchange step of the present invention.

S1. . . Pre-step

S2. . . Photoresist setting step

S3. . . Etching step

S4. . . Photoresist removal step

S5. . . Ion exchange step

Claims (5)

A microlens structure manufacturing method comprises: a pre-step of forming a silver film on a surface of a glass substrate by electroplating; and a photoresist setting step of disposing at least one photoresist layer on the surface of the silver film; An etching step of etching the silver thin film not between the glass substrate and the photoresist layer; a photoresist removing step of removing the photoresist layer on the surface of the silver thin film; and an ion exchange step establishing a The electric field is biased through the silver film and the glass substrate, and the silver ions of the silver film are ion-exchanged with the sodium ions of the glass substrate to form a silver ion layer microlens in the glass substrate. The method for manufacturing a microlens structure according to claim 1, wherein the ion exchange step has an operating temperature of 300 to 500 ° C. The microlens structure manufacturing method according to claim 1, wherein the electric field bias of the ion exchange step is between 300 and 857 V/mm. The microlens structure manufacturing method according to claim 1, wherein the ion exchange step has an operation time of 50 to 100 minutes. The method for manufacturing a microlens structure according to claim 1, wherein the silver film has a thickness ranging from 2 to 10 μm.