BRIEF DESCRIPTION OF THE DRAWINGS
The present invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein:
FIG. 1A is a top view of a substrate employed by the present invention;
FIG. 1B is a cross-sectional view of the substrate shown in FIG 1A;
FIG. 2 is a cross-sectional view of an imprinting die employed by the present invention;
FIG. 3 is a cross-sectional view of an imprinting die coated with a self-assembling monolayer according to the present invention;
FIGS. 4A and 4B are cross-sectional views illustrating an imprinting process employed by an embodiment of the present invention;
FIGS. 5A and 5B are side views illustrating two ink-jet printing processes employed by the present invention; and
FIGS. 6A to 6D are cross-sectional views illustrating a process for fabricating an imprinting die according to the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The microlens module applicable in an optoelectronic device and the method for fabricating the microlens module proposed in the present invention can be more fully understood by reading the following exemplary preferred embodiments.
Referring to FIGS. 1A and 1B, firstly, a substrate 10 is prefabricated and a microlens predetermining distribution region 11 is defined on the substrate 10. (Only two microlens predetermining distribution regions are shown on the substrate 10 in FIGS. 1A and 1B. However, in actual situation, millions of microlens predetermining distribution regions can be defined on the substrate 10 depending on practical requirement.) The substrate 10 is a chip device of an image detector of a digital camera, a chip device of a light emitting diode, or a chip device of a solar cell. Referring to FIG. 1A, the microlens predetermining distribution region 11 is circular, and the region outside the microlens predetermining distribution region 11 is defined as a peripheral region 12. The substrate 10 has a high affinity to a material with a high light transmittance. As the material with a high light transmittance is usually selected from the group consisting of epoxy resins, optical cements, polymethylmethacrylates (PMMAs), polyurethanes (PUs), polydimethylsiloxane (PDMS) or photo-resist materials (such as SU8), the substrate 10 can be made of a material selected from the group consisting of metals (including gold, silver, copper, aluminum, iron, nickel, zirconium or platinum), metal oxides, semiconductors, semiconducting oxides, silicon dioxides (SiO2), glass, quartz or polymeric materials.
Referring to FIG. 2, an imprinting die 20 is prefabricated. The imprinting die 20 is formed with at least a concave portion 21 and a convex portion 22. The dimension and location of the concave portion 21 are corresponding to the microlens predetermining distribution region 11 on the substrate 10. The convex portion 22 surrounds the concave portion 21 and corresponds to the peripheral region 12 on the substrate 10. The imprinting die 20 is preferably made of polydimethylsiloxan (PDMS) and can be fabricated using various methods. FIGS. 6A to 6D show a feasible method. Firstly, as shown in FIG. 6A, a plate 70 such as a plate made of silica is prefabricated. Referring to FIG. 6B, a predetermining portion (a portion corresponding to the peripheral region 12 on the substrate 10) of the plate 70 is removed by photolithography, such that a convex portion 71 and a concave portion 72 can be formed on the plate 70. Then, referring to FIG. 6C, a PDMS material 80 is evenly coated on a surface of the plate 70, such that the PDMS material 80 completely fills up the concave portion 72 and covers the convex portion 71 up to a certain thickness. Lastly, referring to FIG. 6D, after the PDMS material 80 is solidified, the solidified PDMS material block serves as the required imprinting die 20. Furthermore, the imprinting die 20 can also be fabricated using other various methods in addition to the method shown in FIGS. 6A to 6D.
Referring to FIG. 3, after the imprinting die 20 has been fabricated, a self-assembling monolayer (SAM) 30 is coated on the convex portion 22 of the imprinting die 20. The self-assembling monolayer 30 has a low affinity to the material with a high light transmittance. As the material with a high light transmittance is usually selected from the group consisting of epoxy resins, optical cements, polymethylmethacrylates (PMMAs), polyurethanes (PUs), polydimethylsiloxane (PDMS) or photo-resist materials such as SU8, the self-assembling monolayer 30 can be made of a silane compound or a mercaptide.
Referring to FIGS. 4A and 4B, an imprinting process is performed. The concave portion 21 of the imprinting die 20 is aligned with the microlens predetermining distribution region 11 on the substrate 10. Also, the convex portion 22 of the imprinting die 20 is aligned with the peripheral region 12 which is located outside the microlens predetermining distribution region 11 on the substrate 10. Therefore, as shown in FIG. 4B, the self-assembling monolayer (SAM) 30 coated on the convex portion 22 is imprinted onto the substrate 10 and a self-assembling thin layer 31 is formed on the peripheral region 12 on the substrate 10.
Referring to FIG. 5A, an ink-jet printing process is performed. In a liquid status, a material 50 with a high light transmittance is jetted onto the microlens predetermining distribution region 11 on the substrate 10 using an ink-jet device 40. As the material 50 with a high light transmittance has a high affinity to the material of substrate 10, the jetted liquid material 50 with a high light transmittance can be automatically adsorbed on the microlens predetermining distribution region 11 on the substrate 10 and diffused outwards from the microlens predetermining distribution region 11. As the material 50 with a high light transmittance has a low affinity to the self-assembling thin layer 31 which is made of the self-assembling monolayer 30, the liquid material 50 with a high light transmittance is confined to the microlens predetermining distribution region 11 due to the self-assembling thin layer 31. After the jetted material 50 with a high light transmittance is solidified, a required microlens 60 can be formed. In the practical situation, the material 50 with a high light transmittance can be selected from the group consisting of epoxy resins, optical cements, polymethylmethacrylates (PMMAs), polyurethanes (PUs), polydimethylsiloxane (PDMS) and photo-resist materials (such as SU8). Furthermore, the ink-jet device 40 can be a piezoelectric, thermal bubble- or acoustic ink-jet device.
Moreover, referring to FIG. 5B, if a microlens 61 with a larger curvature is needed, the number of droplets of the material 50 with a high light transmittance can be increased. Under a certain number of droplets, the material 50 with a high light transmittance can be completely limited within the microlens predetermining distribution region 11 by the self-assembling thin layer 31. Therefore, theoretically the more the droplets are applied, the larger the curvature of the formed microlens 61 will be resulted.
Apart from the foregoing embodiments, a self-assembling monolayer with a high affinity can be also employed by the present invention, provided that the material of the substrate 10 has a low affinity. Generally speaking, one of the concave portion 21 and the convex portion 22 of the imprinting die 20 is optionally selected as a feature structure region. Further, the feature structure region is corresponded to the microlens predetermining distribution region 11 on the substrate 10. Referring to the foregoing embodiment, the concave portion 21 is selected as the feature structure region. However, in the present embodiment, the convex portion 22 is selected as the feature structure region. Referring to the imprinting process in this situation, the convex portion 22 of the imprinting die 20 is aligned with the microlens predetermining distribution region 11 on the substrate 10 while imprinting the concave portion 21 of the imprinting die 20 onto the peripheral region 12 on the substrate 10. Therefore, the self-assembling monolayer with a high affinity coated on the convex portion 22 is imprinted onto the microlens predetermining distribution region 11 on the substrate 10, so that the microlens predetermining distribution region 11 has a high affinity. The rest of the steps of the present embodiment are the same as those of the foregoing embodiment.
Overall speaking, the present invention proposes a method for fabricating a microlens module by for example an ink-jet printing process on an optoelectronic device, which can be used to fabricate an array of microlenses on an optoelectronic device. The present invention is characterized that a self-assembling monolayer is imprinted onto a substrate using an imprinting technique, so as to define a microlens predetermining distribution region and a peripheral region on the substrate. Then, a material with a high light transmittance is jetted on the microlens predetermining distribution region using an ink-jet printing technique. After the material with a high light transmittance is solidified, a required microlens can be formed. In comparison to prior-art techniques, as the method for fabricating the microlens module on an optoelectronic device does not require complicated and expensive techniques, the present invention is simple in fabrication and cost-effective. Therefore, the present invention is more inventive and practical as compared to prior-art techniques.
It should be apparent to those skilled in the art that the above description is only illustrative of specific embodiments and examples of the present invention. The present invention should therefore cover various modifications and variations made to the herein-described structure and operations of the present invention, provided they fall within the scope of the present invention as defined in the following appended claims.
Patent Application
20080007836
