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Method for fabricating a monolithic fluid injection deviceRelated Patent Categories: Metal Working, Method Of Mechanical Manufacture, Rocket Or Jet Device MakingMethod for fabricating a monolithic fluid injection device description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060236537, Method for fabricating a monolithic fluid injection device. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to thermal ink-jet (TIJ) technology, and more particularly, to a method for fabricating a monolithic fluid injection device. [0003] 2. Description of the Related Art [0004] The conventional fabrication technique of a monolithic fluid injection device typically includes standard integrated circuit (IC) technology and micro-electro-mechanical system (MEMS) technology for both front-end and back-end processes. The front-end process comprises formation of wafer driving circuits and heating elements in an IC foundry. The subsequent back-end process forms fluid chambers and orifices on said wafer in a MEMS foundry. [0005] Both the IC and MEMS processes require one or several thin-film processing techniques, such as metal deposition, dielectric deposition, or etching of dielectric openings. Production costs and the probability of defects, however, increase with repeated thin-film processes. [0006] Conventionally, a monolithic fluid injection device with various components, such as a fluid chamber, a heater, a driving circuit, and an orifice, is formed on a silicon wafer using a MEMS process without requiring packaging and thus results in higher yield and lower cost. [0007] FIGS. 1A and 1B are schematic illustrations of a conventional monolithic fluid injection device fabrication process, wherein FIG. 1A shows the front-end IC process and FIG. 1B shows the back-end MEMS process. Referring to FIG. 1A, a substrate 10 (e.g., silicon wafer) having a first surface and a second surface is provided, and a monolithic fluid injection device is formed thereon. In a typical processing sequence, a patterned sacrificial layer 20 is formed on the first surface of the substrate 10. A patterned structure layer 30 is formed on the first surface of the substrate 10 and covers the patterned sacrificial layer 20. A patterned resistive layer 40 is formed on the structure layer 30 as a heater. A patterned insulating layer 50 having a heater contact opening 45 is formed over the structure layer 30. A patterned conductive layer 60 is formed overlying the structure layer 30 and fills the heater contact opening 45 as a signal transmitting circuit 62. A patterned protective layer 70, having a signal transmitting circuit contact opening and covering the insulating layer 50 and the conductive layer 60, is formed overlying the substrate 10. [0008] Referring to FIG. 1B, the IC processed wafer is then subjected to wet etching. A fluid channel 80 is formed in the second surface of the substrate 10 and exposes the sacrificial layer 20. The sacrificial layer 20 is then removed to form a fluid chamber 90. Thereafter the protective layer 70, the insulating layer 50, the structure layer 30, an orifice 90 connecting the fluid chamber 95 are formed sequentially by lithographic etching. Thus, formation of a monolithic fluid injection device is complete. [0009] The above described formation of the orifice 90 minimally requires etching of the protective layer 70, the insulating layer 50, and the structure layer 30. The front-end process, however, also requires etching of the protective layer 70 and the insulating layer 50 to form an electrical connection between the signal transmitting circuit 62 and the heater 40 to form a signal transmitting contact. [0010] A monolithic fluid injection device combining IC and MEMS processes is disclosed in U.S. Pat. No. 6,102,530. In this method, a structure layer is suspended over the fluid chamber; hence, the process must be precisely controlled to improve production yield and reliability. SUMMARY OF THE INVENTION [0011] An object of the present invention is to provide a less complex method of fabricating a monolithic fluid injection device. By merging part of back-end MEMS process with the front-end IC process, overall process efficiency is improved. [0012] According to the object mentioned above, the present invention provides a method for fabricating a monolithic fluid injection device. A substrate having a first surface and a second surface is provided. A patterned sacrificial layer is formed on the first surface of the substrate. A patterned structure layer is formed on the first surface of the substrate and covers the patterned sacrificial layer. A patterned resistive layer is formed on the structure layer as a heater. A patterned insulating layer having a heater contact opening and a first opening is formed on the structure layer, wherein at least a portion of the heater is exposed through the heater contact opening. A patterned conductive layer is formed overlying the structure layer and connecting the heater via the heater contact opening to form a signal transmitting circuit. A patterned protective layer having a signal transmitting circuit contact opening and a second opening corresponding to the first opening is formed overlying the substrate and covers the insulating layer and the conductive layer. A fluid channel in the second surface of the substrate, opposing the first surface, is formed and exposes the sacrificial layer. The sacrificial layer is removed to form a fluid chamber. The structure layer is etched along the second and the first opening to form an orifice connecting the fluid chamber. [0013] According to the object mentioned above, the present invention provides another method for fabricating a monolithic fluid injection device. A substrate having a first surface and a second surface is provided. A patterned sacrificial layer is formed on the first surface of the substrate. A patterned structure layer is formed on the first surface of the substrate and covers the patterned sacrificial layer. A patterned resistive layer is formed on the structure layer as a heater. A patterned insulating layer having a heater contact opening is formed on the structure layer, wherein at least a portion of the heater is exposed through the heater contact opening. A patterned conductive layer is formed overlying the structure layer and connecting the heater via the heater contact opening to form a signal transmitting circuit. A patterned protective layer is formed overlying the substrate and covers the insulating layer and the conductive layer. A fluid channel in the second surface of the substrate, opposing the first surface, is formed and exposes the sacrificial layer. The sacrificial layer is removed to form a fluid chamber. The protective layer, the insulating layer, and the structure layer are etched to form an orifice connecting the fluid chamber [0014] The present invention provides still another method for fabricating a monolithic fluid injection device. A substrate having a first surface and a second surface is provided. A patterned sacrificial layer is formed on the first surface of the substrate. A patterned structure layer is formed on the first surface of the substrate and covers the patterned sacrificial layer. A patterned resistive layer is formed on the structure layer as a heater. A patterned insulating layer having a heater contact opening is formed on the structure layer, wherein at least a portion of the heater is exposed through the heater contact opening. A patterned conductive layer is formed overlying the structure layer and fills the heater contact opening to form a signal transmitting circuit. A patterned protective layer is formed overlying the substrate and covers the insulating layer and the conductive layer. The protective layer and the insulating layer are etched to form an opening. A fluid channel is formed in the second surface of the substrate, opposing the first surface, and exposes the sacrificial layer. The sacrificial layer is removed to form a fluid chamber. The structure layer is etched along the opening to form an orifice connecting the fluid chamber [0015] The present invention further provides another method for fabricating a monolithic fluid injection device. A substrate having a first surface and a second surface is provided. A patterned sacrificial layer is formed on the first surface of the substrate. A patterned structure layer is formed on the first surface of the substrate and covers the patterned sacrificial layer. A conductive layer is formed on the structure layer. A patterned resistive layer is formed on the conductive layer as a heater. The conductive layer is patterned to form a signal transmitting circuit. A protective layer is formed overlying the substrate and covers the structure layer, the conductive layer, and the resistive layer. The protective layer is etched to form an opening. A fluid channel is formed in the second surface of the substrate, opposing the first surface, and exposes the sacrificial layer. The sacrificial layer is removed to form a fluid chamber. The structure layer is etched along the opening to form an orifice connecting the fluid chamber. [0016] The present invention provides yet another method for fabricating a monolithic fluid injection device. A substrate having a first surface and a second surface is provided. A patterned sacrificial layer is formed on the first surface of the substrate. A patterned structure layer is formed on the first surface of the substrate and covers the patterned sacrificial layer. A conductive layer is formed on the structure layer. A patterned resistive layer is formed on the conductive layer as a heater. The conductive layer is patterned to form a signal transmitting circuit. A protective layer is formed overlying the substrate and covers the structure layer, the conductive layer, and the resistive layer. A fluid channel is formed on a second surface of the substrate, opposing the first surface, and exposing the sacrificial layer. The sacrificial layer is removed to form a fluid chamber. The protective layer and the structure layer is etched sequentially to form an orifice connecting the fluid chamber [0017] The advantage of the present invention is providing a hybrid integrated process for fabricating the orifice of a monolithic fluid injection device. More specifically, integrating portions of the back-end MEMS and front-end IC processes, reduces process cost improves yield. BRIEF DESCRIPTION OF THE DRAWINGS [0018] The present invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein: [0019] FIGS. 1A and 1B are schematic illustrations of the conventional monolithic fluid injection device fabrication process, wherein FIG. 1A shows the front-end IC process and FIG. 1B shows the back-end MEMS process; [0020] FIGS. 2A to 2F are cross-sections illustrating the manufacture of a monolithic fluid injection device according to the first embodiment of the invention, wherein FIGS. 2A to 2D show the front-end IC process and FIGS. 2E to 2F show the back-end MEMS process; [0021] FIGS. 3A to 3C are cross-sections illustrating the manufacture of a monolithic fluid injection device according to the second embodiment of the invention, wherein FIG. 3A shows the front-end IC process and FIGS. 3B and 2C show the back-end MEMS process; Continue reading about Method for fabricating a monolithic fluid injection device... Full patent description for Method for fabricating a monolithic fluid injection device Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method for fabricating a monolithic fluid injection device 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. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method for fabricating a monolithic fluid injection device or other areas of interest. ### Previous Patent Application: Method of forming a gasket assembly for a pem fuel cell assembly Next Patent Application: Evaporator and process for fabricating same Industry Class: Metal working ### FreshPatents.com Support Thank you for viewing the Method for fabricating a monolithic fluid injection device patent info. 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