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  Cmos image sensor and method of manufacturing sameUSPTO Application #: 20070262366Title: Cmos image sensor and method of manufacturing same Abstract: Disclosed are a complementary metal oxide semiconductor (CMOS) image sensor and a method of forming the same. The CMOS image sensor comprises a semiconductor substrate having a photodiode region and a transistor region. An optical path is formed between a micro lens on the photodiode region and a photodiode formed on the semiconductor substrate. The optical path comprises an inner lens formed between an intermetal insulation layer on the photodiode region and a transparent optical region formed on the inner lens. The transparent optical region generally has a different refractive index from the inner lens. (end of abstract) Agent: Volentine & Whitt PLLC - Reston, VA, US Inventors: Hyoun-Min Baek, Duk-Min Yi USPTO Applicaton #: 20070262366 - Class: 257292000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Field Effect Device, Having Insulated Electrode (e.g., Mosfet, Mos Diode), Light Responsive Or Combined With Light Responsive Device, Imaging Array, Photodiodes Accessed By Fets The Patent Description & Claims data below is from USPTO Patent Application 20070262366. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This is a divisional of application Ser. No. 11/207,759, filed on Aug. 22, 2005, which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to a complementary metal oxide semiconductor (CMOS) sensor and a method for manufacturing the same. More particularly, the invention relates to a CMOS sensor having an inner lens located in a planarized insulation layer thereof and a method of manufacturing the same. [0004] 2. Description of the Related Art [0005] Complementary metal oxide semiconductor (CMOS) image sensors are commonly used in various digital imaging applications such as digital cameras and the like. A typical CMOS image sensor includes a light sensing block receiving incident light and a logic block converting the incident light into electrical signals. [0006] CMOS image sensors provide various advantages over competing digital imaging technologies. For example, CMOS image sensors are relatively power efficient and they are readily integrated with other devices on a single chip. [0007] In recent years, CMOS image sensor technology has improved in a number of ways. For example, the optical sensitivity of CMOS image sensors has been improved by increasing a fill factor thereof. Fill factor is a ratio representing the relative amount of a CMOS image sensor occupied by the light sensing block. The fill factor is generally limited by the amount of space on the sensor occupied by the logic block. Hence, the fill factor can be increased by reducing the size of the logic block. [0008] Although the typical size of the logic block in CMOS image sensors has decreased over the years, the corresponding increase in optical sensitivity has been somewhat limited by a corresponding increase in the resolution of the CMOS image sensors. In other words, although the logic blocks have become smaller, modern devices now incorporate more of the logic blocks. As a result, additional measures are needed to improve the optical sensitivity of the CMOS image sensors. [0009] One way to improve the optical sensitivity of a CMOS image sensor includes placing a micro lens on the light sensing block to concentrate incident light thereon. One problem with the micro lens, however, is that its effectiveness is limited by properties of an optical path between the micro lens and the light sensing block. [0010] Various devices and methods have been introduced to improve the concentration of incident light on the light sensing block through the micro lens. Many of these techniques have focused on modifying the optical path between the micro lens and a photodiode in the image sensing block. For example, a dual lens structure is disclosed in U.S. Pat. No. 5,796,154 and a semiconductor array imaging device is disclosed in U.S. Pat. No. 6,171,885. Unfortunately, the above mentioned conventional devices require complicated and expensive fabrication processes. [0011] In order to overcome at least these problems, new CMOS image sensors providing improved optical sensitivity and associated methods of manufacture are needed. SUMMARY OF THE INVENTION [0012] According to some embodiments of the invention, a CMOS image sensor is provided. According to other embodiments of the invention, a method of manufacturing a CMOS image sensor is provided. The CMOS image sensor provides increased optical sensitivity by concentrating incident light on a photodiode through an optical path including an inner lens between a micro lens and the photodiode. [0013] According to one embodiment of the invention, CMOS image sensor comprises a substrate having a photodiode region and a transistor region, a photodiode formed on the photodiode region of the substrate, a plurality of transistors formed on the transistor region of the substrate, a planarized insulation layer covering the photodiode and the plurality of transistors, an intermetal insulation layer formed on the planarized insulation layer, and a metal wire layer formed on the transistor region, the metal wire layer penetrating the intermetal insulation layer. The CMOS image sensor further comprises an inner lens formed on the planarized insulation layer, the inner lens being formed opposite the photodiode as part of the intermetal insulation layer, and a transparent optical region covering the inner lens and penetrating the intermetal insulation layer on the photodiode region. The transparent optical region is preferably formed of a different material from the intermetal insulation layer. [0014] According to another embodiment of the invention, a method of manufacturing a CMOS image sensor comprises forming a substrate having a photodiode region and a transistor region, forming a photodiode on the photodiode region, forming a transistor on the transistor region, forming a planarized insulation layer covering the photodiode and the transistor, forming an intermetal insulation layer covering the planarized insulation layer, and forming a metal wire layer on the transistor region, the metal wire layer penetrating the intermetal insulation layer. The method further comprises forming a cavity penetrating the intermetal insulation layer by removing a portion of the intermetal insulation layer on the photodiode region, forming an inner lens as a part of the intermetal insulation layer in the photodiode region, and forming a transparent optical region on the inner lens by filling the cavity. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The invention is described below in relation to several embodiments illustrated in the accompanying drawings. Throughout the drawings like reference numbers indicate like exemplary elements, components, or steps. In the drawings: [0016] FIG. 1 is a diagram illustrating a pixel sensor of a CMOS image sensor in accordance with an embodiment of the present invention; [0017] FIG. 2 is a cross-sectional view of the pixel sensor shown in FIG. 1 in accordance with one embodiment of the invention; [0018] FIG. 3 is a cross-sectional view of the pixel sensor shown in FIG. 1 in accordance with another embodiment of the invention; [0019] FIG. 4 is a cross-sectional view of the pixel sensor shown in FIG. 1 in accordance with still another embodiment of the invention; [0020] FIG. 5 is a cross-sectional view of the pixel sensor shown in FIG. 1 in accordance with still another embodiment of the invention; Continue reading... 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