Abstract:
A semiconductor device with transistors and a fabricating method therefore are provided. The electrodes of the transistors are formed on the same layer, and they are coupled to one another by a conductor layer. Therefore, the requirement for the vias in whole circuit is reduced, and the cost is decreased.

Description:
BACKGROUND  
       [0001]     1. Field of Invention  
         [0002]     The invention relates to a semiconductor device and in particular to a semiconductor device with a plurality of transistors and a fabricating method therefor.  
         [0003]     2. Related Art  
         [0004]     In a logic circuit, an inverter functions as a basic component. Therefore, whether a circuit is composed of a complementary metal oxide semiconductor (CMOS) inverter, an n-type metal oxide semiconductor (NMOS) inverter, a p-type metal oxide semiconductor (PMOS) inverter or a resistive load inverter, the circuit needs interconnections for the source-to-gate (namely a buffer or source/drain electrode output is used as the input of next circuit level), the source electrode to source/drain electrodes, or the gate to gate (ex. inverter component). Vias are utilized by the conventional method for establishing interconnections of circuits.  
         [0005]     A conventional process of establishing interconnection is described below.  
         [0006]     In the related art, a photolithography and an oxygen plasma etching processes are used to patternize a polyvinyl pyrrolidone (PVP) film for forming a via to connect two interconnecting layers. Then, by an evaporation process or an inkjet printing process, a small molecular or polymer organic semiconductor material is used to patternize the place between the source electrode and the drain electrode in order to produce an organic transistor. (Please refer to H. Klauk, M. Halik, U. Zschieschang, F. Eder, G. Schmid, and C. Dehm,  Pentacene organic transistors and ring oscillators on glass and on flexible polymeric substrates , Applied Physics Letters, Vol. 82, Issue 23, P4175-P4177, 9 Jun. 1996).  
         [0007]     Another related art involves printing carbon ink on a place to be an interconnection portion in advance, and then completing the device. (Please refer to A. Knobloch, A. Manuelli, A. Bernds, and W. Clemens,  Fully printed integrated circuits from solution processable polymers , Journal of Applied Physics, Vol. 96, Issue 4, P2289-P2291, 15 Aug. 2004).  
         [0008]     Another related art involves disposing metal lines at two sides of the substrate then connecting them with vias. (Please refer to B. Crone, A. Dodabalapur, Y.-Y. Lin, R W Filas, Z. Bao, A. LaDuca, R. Sarpeshkar, H E Katz, W. Li,  Large - scale complementary integrated circuits based on organic transistors , Nature, Vol. 403, P521-P523, 2000).  
         [0009]     There is one another related art using a shadow mask pattern technique. (Please refer to P F Baude, D A Ender, M A Haase, T W Kelley, D V Muyres, and S D Theiss,  Pentacene - based radio - frequency identification circuitry , Applied Physics Letters, Vol. 82, Issue 22, P3964-P3966, 2 Jun. 2003)  
         [0010]     However, in a conventional process of organic electronics, vias are generally produced by a laser drill process, or produced by a photolithography or a plasma etching processes, which costs a lot of money and complicates the process. Therefore, using those kinds of techniques defeats the purpose of making the process easier and making the organic electronics cheaper.  
       SUMMARY  
       [0011]     An object of the invention is to provide a semiconductor device with transistors and a fabricating method therefor to reduce the number of vias in a circuit.  
         [0012]     According to the invention, an embodiment of the method for fabricating a semiconductor device with transistors includes the steps of: providing a substrate; forming a first conductive layer on the substrate, where the first conductive layer includes a first electrode region and at least one second electrode region; the first electrode region electrically connects to one of the second electrode regions; forming a first semiconductor layer to cover the second electrode region; forming a dielectric layer to cover the first electrode region and the first semiconductor layer; forming a second semiconductor layer on the dielectric layer that corresponds to the first electrode region; and forming a second conductive layer that includes a third electrode region, which corresponds to the second electrode region, on the dielectric layer, and a fourth electrode region, which corresponds to the first electrode region, on the second semiconductor layer.  
         [0013]     The invention provides another embodiment of the method for fabricating a semiconductor device with transistors, which includes the steps of: providing a substrate; forming a first conductive layer on the substrate, where the first conductive layer includes a first electrode region and one second electrode region; forming a first semiconductor layer to cover the second electrode region; forming a dielectric layer to cover the first electrode region and the first semiconductor layer; forming a second semiconductor layer on the dielectric layer that corresponds to the first electrode region; and forming a second conductive layer that includes a third electrode region, which corresponds to the second electrode region, on the dielectric layer, and forth electrode regions, which correspond to the first electrode region, on the second semiconductor layer, where the third electrode region electrically connects to one of the fourth electrode regions.  
         [0014]     In addition, according to the methods above, a semiconductor device with the first electrode region electrically connecting to one of the second electrode regions, or a semiconductor device with a plurality of transistors having the third electrode region electrically connecting to the fourth electrode region can also be obtained. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention will become more fully understood from the detailed description given below, which is for illustration only and thus is not limitative of the invention, wherein:  
         [0016]      FIGS. 1A  to  1 F show the cross section diagrams of an embodiment of a method for fabricating a semiconductor device according to the invention;  
         [0017]      FIG. 2  is a top view of  FIG.1B ; and  
         [0018]      FIG. 3  is a top view of  FIG. 1F . 
     
    
     DETAILED DESCRIPTION  
       [0019]     The concept of the invention is to make the electrodes to be electrically connected may connect with one another on the same layer, and directly connect the two terminals connected to one another by a conductive layer. This dramatically reduces the number of vias used based on practical circumstances.  
         [0020]     Please refer to  FIGS. 1A  to  1 F, showing a flow chart of the fabricating method of the semiconductor device according to an embodiment of the invention. In  FIG. 1A , a substrate  110  is provided.  
         [0021]     The preferred material of the substrate is an isolating material, such as a polymer, a plastic or a glass. The material can be rigid or flexible and also can be a printing circuit board (PCB) material that includes an epoxy or a ceramic and has a silicon isolation layer or a silicon oxide isolation layer thereon.  
         [0022]     Next, a first conductive layer  120  is formed on the substrate  110 , where the first conductive layer  120  includes a first electrode region  122  (i.e. first electrode) and at lease one second electrode region  124  and  126  (i.e. second electrode), as shown in  FIG. 1B .  
         [0023]     The first conductive layer can be made of any kind of conductive material with a conductivity of about 10 −2  to 10 6  S/cm. Here, the conductive material can be a high conductive material such as Au, Ag, Cu, Ni, Ti, Pt, Nd, or other high conductive metal compounds of composition of the above elements, a conductive polymer such as a polyaniline (PANI) or polyethylene dioxythiophene: polysterene sulfonic acid (PEDOT:PSS), or a conductive oxide such as indium tin oxide (ITO) or indium zin oxide (IZO). Except for choosing a high conductivity material, another factor for choosing a preferred material for the first conductive layer is how the material matches to the first semiconductor layer and the device.  
         [0024]     As shown in  FIG. 1C , a first semiconductor layer is formed to cover the second electrode regions  124  and  126 .  
         [0025]     A material for the first semiconductor layer can include an electron-hole transporting material (i.e. p-type semiconductor layer) or an electron transporting material (i.e. n-type semiconductor layer). Here, the electron-hole transporting material can be a pentacene, a poly (3-hexylthiophene) (P3HT), a p-type material such as a derivative of the above compounds, or a p-type material mixed with cathode materials. The cathode materials can be carbon nanotubes, Si nanowires, SiC/Si nanoneedles, SiCN nanorods, AlN nanoneedles, or other inorganic nanoneedles. The electron transporting material can be a copper hexadecafluorophthalocyanine (F16CuPc), a perylene-tetracarboxylic-diimide (PTCDI), a carbon sixty (C 60 ), an n-type material such as a derivative of the above compounds, or an n-type material mixed with cathode materials. The cathode materials can be carbon nanotubes, Si nanowires, SiC/Si nanoneedles, SiCN nanorods or AlN nanoneedles.  
         [0026]     Then, a dielectric layer  140  is formed on the first electrode region  122  and the first semiconductor layer  130  as shown in  FIG. 1D . In other words, a covered dielectric layer  140  can be grown thereon.  
         [0027]     The dielectric constant of the dielectric layer is larger than 1. Also, a material for the dielectric layer can be a polymer isolating material such as a poly vinyl alcohol (PVA), a poly vinyl pyrrolidone (PVP), a polyacrylonitrile (PAN), a polystyrene (PS), a polymethylmethacrylate (PMMA) or a mixture of the compounds above, an inorganic material such as a SiO 2 , SiN, Al 2 O 3 , TiO 2 , HfO 2 , ZrO 2  or Ta 2 O 5 , or a polymer isolating material or its mixture that is mixed with an inorganic material. The inorganic material can be SiO 2 , SiN, Al 2 O 3 , TiO 2 , HfO 2 , ZrO 2  or Ta 2 O 5 . The choice for the preferred material of the dielectric layer depends on how it matches to the process as well as the current leakage extent of the material to the device.  
         [0028]     A second semiconductor layer  150  is formed on the dielectric layer  140  corresponding to the first electrode region  122 , as shown in  FIG. 1E .  
         [0029]     The material for the second semiconductor layer can include an electron-hole transporting material (i.e. p-type semiconductor layer) or an electron transporting material (i.e. n-type semiconductor layer). Here, the electron-hole transporting material can be a pentacene, a P3HT, a p-type material such as a derivative of the above compounds, or a p-type material mixed with cathode materials. The cathode materials can be carbon nanotubes, Si nanowires, SiC/Si nanoneedles, SiCN nanorods, AlN nanoneedles, or other inorganic nanoneedles. The electron transporting material can be a F16CuPc, a PTCDI, a C 60 , an n-type material such as a derivative of the above compounds, or an n-type material mixed with cathode materials. The cathode materials can be carbon nanotubes, Si nanowires, SiC/Si nanoneedles, SiCN nanorods or AlN nanoneedles.  
         [0030]     Finally, a second conductive layer  160  is formed. The second conductive layer  160  includes a third electrode region  162  (i.e. third electrode) and fourth electrode regions  164  and  166  (i.e. fourth electrode), as shown in  FIG. 1F . Among them, the second conductive layer  160  can be made of any kind of conductive material, with a conductivity of about 10 −2  to 10 6  S/cm. Here, the conductive material can be a high conductive material such as Au, Ag, Cu, Ni, Ti, Pt, Nd, a high conductive metal compound such as a composition of the above elements, a conductive polymer such as a PANI or a PEDOT:PSS, or conductive oxides such as ITO or IZO.  
         [0031]     In order to clearly describe the invention, only two semiconductor devices are formed in this embodiment, including a third electrode region  162  located at the dielectric layer  140  at the middle of the area corresponding to the second electrode regions  124  and  126 , and the fourth electrode regions  164  and  166  located at the second semiconductor layer  150  corresponding to the two side of the first electrode region  122 .  
         [0032]     In this embodiment, the first electrode region  122  can be electrically connected to one of the second electrode regions  124  and  126  (shown in  FIG. 2 ), or the third electrode region  162  can be electrically connected to one of the fourth electrode regions  164  and  166  (shown in  FIG. 3 ) to electrically connect the two semiconductor devices. In other words, when the first electrode region  122  and the third electrode region  162  are used as gate electrodes, and the second electrode regions  124  and  126  and the fourth electrode regions  164  and  166  are used as source/drain electrodes, a new type of semiconductor device where two transistors have gate to source/drain electrode interconnection can be obtained.  
         [0033]     Here, although the description above proceeds by the structure of gate to source/drain electrodes, similarly, two interconnecting semiconductor devices with structures of source electrode to gate, source electrode to source/drain electrodes or gate to gate can also be obtained by modifying the electrode regions of the conductive layers and the semiconductor layers.  
         [0034]     Next, every layer (i.e. the first conductive layer, the first semiconductor layer, the dielectric layer, the second semiconductor layer and the second conductive layer) can be formed by depositing or coating and then patternizing processes according to requirements.  
         [0035]     For example, by depositing or coating the conductive material and then patternizing it by a lithographic printing process according to requirements, the structures for the first conductive layer and the second conductive layer can be formed. Besides, other technologies also can be used for producing the same structure.  
         [0036]     In addition, the semiconductor with two transistors described here is only for the purpose of clear description. The same concept can apply to a semiconductor with multiple transistors. In other words, forming the electrodes connecting the transistors on the same layer and using the conductive layers to connect the terminals can dramatically reduce the number of vias in a circuit and thus decrease the cost.  
         [0037]     While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly the appended claims are intended to cover all embodiments, which do not depart from the spirit and scope of the invention.