Microlens Structure for Image Sensors
a microlens and image sensor technology, applied in the field of semiconductor structures, can solve the problems of reducing design sizes, difficult to prevent the merging of microlenses, and incurred during the fabrication of microlenses
Inactive Publication Date: 2010-07-01
TAIWAN SEMICON MFG CO LTD
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Benefits of technology
[0012]In accordance with an embodiment of the present invention, a method of forming an image sensing semiconductor device is provided. The method comprises providing a substrate having an image sensing portion and a logic portion, the image sensing portion having a plurality of photo-sensitive devices formed thereon and the logic portion having one or more interconnection layers. A photo-sensitive layer is formed over the image sensing portion and a plurality of exposures are performed in accordance with a mask, the exposures exposing at least a portion of the photo-sensitive layer. At least a portion of the photo-sensitive layer exposed during the exposures is removed and the remaining portions of the photo-sensitive layer form one or more microlenses. Thereafter, the microlenses are reflowed.
Problems solved by technology
Problems, however, may be incurred during the fabrication of the microlenses as the design sizes are reduced.
The reflow procedure, which uses high temperatures, is difficult to control and, thus, it is difficult to prevent the microlenses from merging as the distance between microlenses decreases.
Another problem often seen is related to the focal length.
Method used
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[0017]The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.
[0018]Embodiments of the present invention are described in the context of a CMOS image sensor, which is one application of the present invention that has been found to be particularly useful. Embodiments of the present invention, however, may be used to form microlenses for other types of devices, including charged-coupled device (CCD) image sensors.
[0019]FIGS. 1-4 illustrate cross-section views of a wafer 100 during various steps of a method of fabricating microlenses in accordance with an embodiment of the present invention. The process begins in FIG. 1, wherein the wafer ...
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A microlens structure and a method of fabrication thereof are provided. The method comprises forming a layer of microlens material over a substrate, which has photo-sensitive elements formed therein. The microlens material, which comprises a photo-resist material, is exposed in accordance with a desired pattern a plurality of times. The energy used with each exposure process is less than the energy required if a single exposure is used. Furthermore, the masks used for each exposure may differ. In an embodiment, the masks are varied so as to create a notch in the upper corner of the microlens. The microlens structure may have a height less than about 0.5 um and / or a gap between microlenses less than about 0.2 um. In an embodiment, one or more dielectric layers having a combined thickness greater than about 3.5 um are interposed between the photo-sensitive elements and the microlenses.
Description
[0001]This application is a continuation application of U.S. patent application Ser. No. 11 / 181,508, filed on Jul. 14, 2005, entitled “Microlens Structure for Image Sensors,” which claims the benefit of U.S. Provisional Application No. 60 / 655,489, filed on Feb. 23, 2005, entitled “Microlens for Image Sensors,” which applications are hereby incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates generally to semiconductor structures, and more particularly, to microlenses for use with image sensors.BACKGROUND[0003]Digital imaging systems such as digital cameras utilize semiconductor chips equipped with photo-sensitive electronic components, such as photo-diodes. The digital imaging systems typically capture light information in a series of pixels. Commonly, the pixels are arranged in an array of rows and columns, such as 1024×768 pixels. Each pixel is represented by at least one photo-sensitive component. In applications requiring the capture of color, colo...
Claims
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IPC IPC(8): H01L31/0232
CPCH01L27/14627H01L27/14685H01L27/146
InventorKAO, MING-CHANGCHANG, CHIH-KUNGWENG, FU-TIENCHANG, BII-JUNQ
OwnerTAIWAN SEMICON MFG CO LTD