Abstract:
There is disclosed a method of manufacturing a semiconductor device utilizing a gate dielectric film. The present invention can obtain a (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film where its the dielectric constant is higher than that of Al 2 O 3  and its leakage current characteristic is improved compared to TiO 2 , by depositing a Ti 1−X Al X N film on a semiconductor substrate and then forming the (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film by oxidization process. Therefore, the present invention can implement a high-speed high-density logic device and an ultra high integration device of more than 1G DRAM class, which utilize a high dielectric material as the gate dielectric film.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Priority is claimed from Republic of Korean Patent Application No. 99-61810 filed Dec. 24, 1999, which is incorporated in its entirety by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to a method of manufacturing a semiconductor device utilizing a gate dielectric film. More particularly, the present invention relates to a method of manufacturing a semiconductor device capable of improving a leakage current characteristic of a gate dielectric film, while increasing its dielectric constant, applied to a high-speed high-density logic device and an ultra high integration device of more than 1G DRAM class, which utilize a high dielectric material as a gate dielectric film. 
     2. Description of the Prior Art 
     In general, a gate dielectric film of DRAM devices presently mass-produced and of a logic device in a semiconductor device is used by growing SiO 2  by means of annealing process or rapid thermal process. As the design rule is scaled down, a SiO 2  gate dielectric film is scaled down to 25˜30 Å being a limit to the tunneling effect. It is expected that the gate dielectric of 0.10 μm technology will result in 30˜40 Å in thickness. Due to off-current by the tunneling of the gate dielectric film, however, there is a possibility that the static power consumption is increased and its operation performance is adversely affected. Particularly, in case of a memory device, a scheme to reduce a leakage current becomes an important issue. As a part of efforts to overcome this, a research for adopting a dielectric material having a high dielectric constant as a gate dielectric film has been carried out. 
     Recently, research for using dielectric materials such as TiO 2 , Al 2 O 3 , etc. as a gate dielectric film has been actively carried out. Al 2 O 3  has a dielectric constant of 8˜15, which is larger about 2.5 times than the dielectric constant of a thermal oxide film, and has a good leakage current characteristic. However, there is a problem that Al 2 O 3  is utilized as a gate dielectric film since its dielectric constant is degraded depending on its thickness in controlling the thickness (Tox) of the effective oxide film to below 25˜30 Å. Also, it is reported that TiO 2  has a high dielectric constant of 25˜40. However, there is a problem that TiO 2  is utilized as a gate dielectric film since its leakage current characteristic is poor. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a method of manufacturing a semiconductor device capable of improving a leakage current characteristic of a gate dielectric film, while increasing its dielectric constant, applied to a high-speed high-density logic device and an ultra high integration device of more than 1G DRAM class which utilize a high dielectric material as the gate dielectric film. 
     In order to accomplish the above object, a method of manufacturing a semiconductor device according to the present invention is characterized in that it comprises the steps of depositing a Ti 1−X Al X N film on a semiconductor substrate; oxidizing the Ti 1−X Al X N film by oxidization process to form a (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film; and forming a gate electrode on the (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned aspects and other features of the present invention will be explained in the following description, taken in conjunction with the accompanying drawings, wherein: 
     FIGS. 1A and 1C are cross-sectional views of a device for explaining a method of manufacturing a semiconductor device utilizing a gate dielectric film according to a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention will be described in detail by way of a preferred embodiment with reference to accompanying drawings. 
     FIGS. 1A and 1C are cross-sectional views of a device for explaining a method of manufacturing a semiconductor device utilizing a gate dielectric film according to a preferred embodiment of the present invention. 
     Referring now to FIG. 1A, a device separation film  12  is formed in a semiconductor substrate  11 , thus defining an active region. Then, a Ti 1−X Al X N film  13  is deposited on the semiconductor substrate in which the device separation  12  is formed. 
     In the above, the device separation film  12  may be formed in a LOCOS structure or a STI structure. The Ti 1−X Al X N film  13  is deposited in thickness of 20˜150 Å by use of physical vapor deposition (PVD) method or chemical vapor deposition (CVD) method. 
     In case that the Ti 1−X Al X N film  13  is deposited by PVD method, two methods may be employed depending on their deposition conditions. Firstly, in a target composition of TiAl X  in which the composition ‘X’ is 0.25˜0.35, in case that the Ti 1−X Al X N film  13  is deposited by PVD method using a nitrogen reactive sputtering, the deposition conditions are as follows: a power of 500 W˜7 kW (in case of the chamber for 8 inch) is applied, the flow rate of N 2  is 20˜80 sccm, the flow rate of Ar is 5˜25 sccm and the deposition temperature is in the range of −30˜500° C. Secondly, in a target composition of TiAlN in which the composition of AlN is 25˜35%, in case that the Ti 1−X Al X N film  13  is deposited by PVD method using sputtering, a DC or a RF bias is applied and Ar, Xe, Kr, etc. are used as a sputtering gas. 
     In case that the Ti 1−X Al X N film  13  is deposited by CVD method, two methods may be employed depending on their conditions. Firstly, in case that the Ti 1−X Al X N film  13  is deposited by CVD method using a thermal oxidization method, the deposition conditions are as follows: TiCl 4 , TDMAT, etc. are used as a Ti source material, AlCl 3 , Al(CH 3 ) 3 , etc. are used as an Al source material, NH 3 , ND 3 , N 2 , etc. are used as a N source material and its deposition temperature is in the range of 450˜700° C., wherein the composition of AlN is controlled to be 25˜35%. Secondly, in case that the Ti 1−X Al X N film  13  is deposited by CVD using ECR (Electron Cyclotron Resonance) employing a remote plasma of 2˜9 GHz or a RF of 13.56 MHz, the depositions are as follows: TiCl 4 , TDMAT, etc. are used as a Ti source material, AlCl 3 , Al(CH 3 ) 3 , etc. are used as an Al source material and NH 3 , ND 3 , N 2 , etc. are used as a N source material, wherein the composition of AlN is controlled to be 25˜35%. 
     Meanwhile, before the Ti 1−X Al X N film  13  is deposited, the following processes may be implemented. 
     Firstly, before the Ti 1−X Al X N film  13  is deposited, a trench capacitor structure may be formed. At this time, oxide/nitride or Ta 2 O 5 , Al 2 O 3 , BST, SBT are used as a dielectric film of a capacitor. 
     Secondly, before the Ti 1−X Al X N film  13  is deposited, pirahna, RCA cleaning process may be performed in order to remove a SiO 2  film having a bad film quality on the surface of the semiconductor substrate  11 . 
     Thirdly, before the Ti 1−X Al X N film  13  is deposited, a SiO 2  film having a good film quality is formed in thickness of 3˜20 Å on the surface of the semiconductor substrate  11  in order to improve the interfacial property between the semiconductor substrate  11  and the Ti 1−X Al X N film  13 . As the SiO 2  film having a good film quality is an thermal oxide film by furnace, it may be formed at the temperature of 650˜900° C. by wet or dry method, or may be formed by rapid thermal process having the chamber temperature of 700˜900° C. under O 2  atmosphere or N 2 O atmosphere at a constant pressure or a reduced pressure of 0.1˜100 Torr. 
     Referring now to FIG. 1B, the Ti 1−X Al X N film  13  is oxidized by oxidization process to form a (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film  130 . Here, the composition ‘X’ is 0.25˜0.35 in a (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film  130 . 
     In the above, the oxidization process may include annealing under O 2  or N 2 O atmosphere using a furnace anneal for 20 seconds ˜5 minutes, performing a plasma process using plasma under O 2  or N 2 O atmosphere at the temperature of 350˜650° C. or annealing using UV/O 3  under O 2  or N 2 O atmosphere at the temperature of 350˜550° C. for 5˜30 minutes. 
     Meanwhile, in order to improve the film quality of the (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film  130 , it may be experienced by annealing process using the furnace anneal under O 2 , N 2  and N 2 O atmosphere at the temperature of 650˜800° C. for 10˜60 minutes or by rapid thermal process under O 2 , N 2  and N 2 O atmosphere with the condition of ramp rate having 20˜80° C./sec at the temperature of 600˜900° C. for 10˜120 seconds. 
     Referring now to FIG. 1C, a gate electrode  14  is formed on the (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film  130 , thus forming a semiconductor device having a gate dielectric structure. 
     In the above, the gate electrode  14  may be formed of a polysilicon structure, a polycide structure such as tungsten polycide (W-polycide), titanium polycide (Tipolycide), molybdenum polycide (Mo-polycide), cobalt polycide (Co-polycide), etc., metal structures such as tungsten (W), tantalum (Ta), tungsten nitride (WN), tantalum nitride (TaN), etc., which are used conventionally. 
     As mentioned above, the present invention relates to a technology of forming a (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film in which TiO 2  and Al 2 O 3  are mixed as a gate dielectric film of a semiconductor device, wherein the gate dielectric film is higher in the dielectric constant than Al 2 O 3  and its leakage current characteristic is improved compared to TiO 2 . 
     In other words, in the (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film, the dielectric constant and the leakage current characteristic can be adjusted by controlling the composition ‘X’ of 0.25˜0.35. At this time if TiO 2  is 65˜75% and Al 2 O 3  is 25˜35%, the dielectric constant is increased to 18˜20 and the leakage current characteristic can be also improved. The (Al 2 O 3 ) X —(TiO 2 ) 1−X  gate dielectric film is formed by depositing a SiO 2  film with the ultra thin thickness of 3˜20 Å, then depositing a Ti 1−X Al X N film by PVD method or CVD method and performing oxidization process under various conditions. 
     Advantage of using oxidization of the Ti 1−X Al X N film is that it can control a micro-structure of a thin film, depending on the deposition conditions such as deposition temperature, power, flow rate of gas, etc. For example, if the Ti 1−X Al X N film is deposited a low temperature of below 100° C., it is deposited in an amorphous phase of nano crystalline. On the other hand, if is deposited at a high temperature of more than 400° C., it is deposited in a preferred orientation phase of ( 200 ) NaCl structure. If the Ti 1−X Al X N film deposited by low temperature deposition process is oxidized, it has a mixed phase in which ( 101 ) rutile and ( 400 ) anatase TiO 2  are mixed. If the Ti 1−X Al X N film deposited by high temperature deposition process is oxidized, it has a (Al 2 O 3 ) X —(TiO 2 ) 1−X  compound in which a ( 400 ) anatase TiO 2  phase of a preferred orientation is intact viewed. 
     As mentioned above, the present invention can implement a high-speed highdensity device having a good leakage current characteristic, by utilizing a (Al 2 O 3 ) X −(TiO 2 ) 1−X  gate dielectric film having a high dielectric constant when forming a next-generation gate. 
     The present invention has been described with reference to a particular embodiment in connection with a particular application. Those having ordinary skill in the art and access to the teachings of the present invention will recognize additional modifications and applications within the scope thereof. 
     It is therefore intended by the appended claims to cover any and all such applications, modifications, and embodiments within the scope of the present invention.