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  Solid-state imaging device and method for manufacturing the sameUSPTO Application #: 20060038204Title: Solid-state imaging device and method for manufacturing the same Abstract: A transfer film, on which an adhesive is applied, is glued to plural spacers formed on a glass substrate. The glass substrate is laid on a working table, and one end of the transfer film is fixed to a winding roller. A peeling guide is set at a position over the transfer film. The winding roller is driven to wind the transfer film while the working table moves horizontally. While winding the transfer film, the angle between the glass substrate and the transfer film is kept constant. After the transfer film is peeled off, the adhesive is uniformly transferred to each of the spacers. (end of abstract) Agent: Sughrue Mion, PLLC - Washington, DC, US Inventors: Kosuke Takasaki, Kazuhiro Nishida, Kiyofumi Yamamoto USPTO Applicaton #: 20060038204 - Class: 257232000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Field Effect Device, Charge Transfer Device, Non-electrical Input Responsive (e.g., Light Responsive Imager, Input Programmed By Size Of Storage Sites For Use As A Read-only Memory, Etc.), Having Structure To Improve Output Signal (e.g., Exposure Control Structure), Having Alternating Strips Of Sensor Structures And Register Structures (e.g., Interline Imager) The Patent Description & Claims data below is from USPTO Patent Application 20060038204. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This is a divisional of application Ser. No. 10/807,348 filed Mar. 24, 2004. The entire disclosure is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a method for manufacturing a solid-state imaging device by use of wafer level chip size packaging technique, and a solid-state imaging device manufactured by such manufacturing method. [0004] 2. Description of the Related Art [0005] Digital cameras, equipped with a solid-state imaging device and a semiconductor memory device, are widely spread among consumers. In addition, small electric apparatus, such as a mobile phone and a personal digital assistance (PDA), has the solid-state imaging device and the memory device to enable digital photography. A conventional solid-state imaging device is manufactured by the following steps. First, a solid-state imaging element chip, such as a charge coupled device (CCD) formed on a wafer, is die-bonded on a package formed from a ceramic, for instance. Then, after the terminals of the solid-state imaging element chip and the terminals of the package are electrically connected by bonding wires, a glass lid formed from a transparent glass is fixed to the package to seal the solid-state imaging element chip. [0006] Small solid-state imaging device is preferable in terms of miniaturizing the digital camera and the small electric apparatus. As for an example to reduce the size of the solid-state imaging device, a wafer level chip size packaging technique (hereinafter referred to as "wafer level CSP") can package the solid-state imaging device without the packaging material. For instance, Japan Patent Laid-Open Publication (JP-A) No. 2002-231921 describes the solid-state imaging device, manufactured by the wafer level CSP technique, in which a spacer is bonded to the peripheral area of the upper surface of the solid-state imaging element chip. The cover glass is provided on the spacer to seal the solid-state imaging element chip. The solid-state imaging element chip has connection terminals on the upper, bottom or lateral surface. [0007] In manufacturing the solid-state imaging device by the wafer level CSP technique, plural spacers are formed on the glass substrate as the cover glass. Then, after adhesives are applied to the edge surface of the spacers, the glass substrate is adhered to a wafer on which plural solid-state imaging element chips are formed. The wafer with the glass substrate is subject to dicing process to manufacture the solid-state imaging device. [0008] It is necessary to provide a space between the solid-state imaging element and the spacer for the purpose of preventing flare that is caused by entering incident light, reflected on the inner surface of the spacer, into the solid-state imaging element. Moreover, since the spacer is pressed onto the solid-state imaging device to generate a stress during the bonding process, the spacer and the solid-state imaging device are distorted. Thus, the space between the solid-state imaging element and the spacer is necessary for preventing such distortion to the solid-state imaging device. Furthermore, because the solid-state imaging element generates much heat when the solid-state imaging device is operated at a high clock rate or takes an image for a long exposure time, the difference in thermal expansion rate between the solid-state imaging element chip and the spacer causes stress. The space between the solid-state imaging element and the spacer is necessary to prevent such stress from affecting the solid-state imaging element. [0009] In bonding the spacer to the wafer, if the adhesives are flowed on the solid-state imaging element chip, the solid-state imaging device does not work properly because of noise interference caused by the flowed adhesive. Moreover, if the gap between the spacer and the wafer is not tightly sealed, the solid-state imaging device is damaged by cooling water during the dicing process. Thus, in order to increase productivity, the spacer must be tightly bonded to the wafer. [0010] For the purpose of proper bonding, the adhesives applied on the spacer must be thin and uniform in thickness over the applied area. Although a small amount of adhesive with high viscosity is dropped on the spacer by potting method according to the above publication, putting the adhesives on the spacer having the width less than 200 .mu.m is technically difficult. Even if the spacer has the width more than 200 .mu.m, dropping the adhesives on all bonded surfaces of the plural spacers takes too much time for the adhering process. [0011] In addition the above publication describes a method to apply the adhesive to the spacer by printing, but printing the adhesive is hardly realized because it is difficult to control the thickness and the position of the adhesive to be printed on the spacer. Moreover, silicon spacer tends to repel the adhesive, so it is also difficult to control the thickness and flatness of the adhesives to be put on the spacer. [0012] In order to bond the spacer properly to the wafer, the width of the frame-shaped spacer is necessary to be considered. If the width of the spacer is too large, an improper bonding will happen because of air remaining inside the adhesive. Moreover, large width spacer will make it difficult to decrease the size of the solid-state imaging device. Thus, the manufacture cost will increase because of the small number of solid-state imaging devices per wafer. On the other hand, if the width of the spacer is too narrow, the solid-state imaging device will be physically weak. [0013] For the purpose of preventing the adhesive from flowing into the solid-state imaging element, it is effective to lengthen the distance between the solid-state imaging element and the spacer. Making the distance longer, however, will increase the manufacture cost because of difficulty in miniaturizing the solid-state imaging device. SUMMARY OF THE INVENTION [0014] An object of the present invention is to provide a method for manufacturing a solid-state imaging device that is capable of bonding the spacers properly to the solid-state imaging elements on the wafer. [0015] Another object of the present invention is to provide a solid-state imaging device that is manufactured by such manufacturing method. [0016] To achieve the above object, the solid-state imaging device is manufactured by use of a transfer member to transfer an adhesive to a frame-shaped spacer to be bonded to a wafer on which plural solid-state imaging elements area formed. The spacers are formed in a transparent substrate, and each of the spacers surrounds the solid-state imaging element. The transfer member, which the adhesive is applied to, is stuck to the spacers. After applying the pressure to the transparent substrate and the transfer member, the transfer member is released from the transparent substrate to transfer the adhesive layer on the spacer. [0017] The transfer member may be a rigid body such as a glass plate. It is also possible to form the transfer member from an elastic body, such as a flexible plastic film. The flexible film as the transfer member is preferably peeled off in such a manner that the angle between the transfer member and the transparent substrate is kept constant. The transfer member may have a ridge pattern or a recess pattern that is the same pattern as the spacers in the transparent substrate. It is also possible to apply a release agent, such as silicon, on the surface of the transfer member. [0018] It is possible to carry out surface modification to the surface of the spacer to which the adhesive of the transfer member is to be contacted. The viscosity of the adhesive is preferably 0.1 Pas or more. The adhesive is applied to the transfer member by bar coating, blade coating or spin coating. In addition, it is preferable to apply air pressure or roller pressure to the transfer member and the transparent substrate. [0019] The viscosity of the adhesive at the time of transferring to the spacer is preferably 100 Pas to 10000 Pas. The thickness of the adhesive is 0.5 .mu.m to 5 .mu.m when the adhesive is activated. The spacer may be bonded to the wafer over the surface to which the adhesive is applied. [0020] The solid-state imaging device, manufactured by the above methods, may have the following features. The solid-state imaging element and the inner surface of the spacer are separated by 50 .mu.m to 100 .mu.m over the whole edge of the solid-state imaging element. The width of the spacer is 100 .mu.m to 500 .mu.m. It is possible to form chamfer edges in the surface of the spacer to which the adhesive is applied. The surplus of the adhesive is contained in the space between the wafer and the chamfer edges. [0021] According to the present invention, since the adhesive is applied to the spacer by use of the transfer member with the adhesive, it is possible to apply thin adhesive on spacers evenly at a desired thickness. Thereby, the spacers are bonded properly to the wafer without forming a gap therebetween. It is also possible to prevent the adhesive from being flowed to the solid-state imaging element. Continue reading... Full patent description for Solid-state imaging device and method for manufacturing the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Solid-state imaging device and method for manufacturing the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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