Abstract:
A method of forming an ultra thin dielectric film or dielectric layer on a semiconductor device is disclosed. In one embodiment of the present invention, an oxide layer is formed over a substrate. A silicon-containing material is deposited over the oxide layer. The deposited material and oxide layer are processed in a plasma to form the dielectric layer or ultra thin dielectric film. The silicon-containing dielectric layer can allow for improved or smaller semiconductor devices. The silicon containing dielectric layer can be fabricated at low temperatures. Improved or smaller semiconductor devices may be accomplished by reducing leakage, increasing the dielectric constant or fabricating at lower temperatures.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is related to commonly assigned U.S. patent application Ser. No.: 09/653,639, METHOD FOR FORMING A BARRIER LAYER AND A SEMICONDUCTOR DEVICE INCORPORATING THE SAME, filed Aug. 31, 2000, by Powell et al. and Ser. No. 09/653,096, METHOD FOR FORMING A DIELECTRIC LAYER AND A SEMICONDUCTOR DEVICE INCORPORATING THE SAME, filed Aug. 31, 2000, by Powell et al., the disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of semiconductors and, more particularly, to forming a dielectric layer at a low temperature. 
     BACKGROUND OF THE INVENTION 
     There is an increasing demand for semiconductor devices of reduced size. The performance characteristics of semiconductor devices become more important as device size decreases. Accordingly, processes that enhance performance characteristics are important to improved semiconductor fabrication. For example, capacitor performance can be improved by improving the dielectric constant of the capacitor&#39;s dielectric layer and reducing leakage across the dielectric layer. 
     Ultra thin dielectric films can greatly affect the performance of semiconductor devices. Ultra thin films are normally used as dielectric layers in semiconductor devices. Conventional ultra thin films and dielectric fabrication methods require high temperatures and are often inadequate to allow significant reduction of semiconductor device size. 
     Accordingly, there is a need in the art for an improved method of forming a dielectric layer or ultra thin dielectric film. 
     SUMMARY OF THE INVENTION 
     This need is met by the present invention wherein a method of forming an ultra thin dielectric film or dielectric layer on a semiconductor device is disclosed. According to one embodiment of the present invention, a semiconductor device is provided. An oxide layer is formed over the semiconductor device. A silicon-containing material is deposited over at least a portion of the oxide layer. The oxide layer and deposited silicon-containing material are converted to the ultra thin dielectric film by processing the deposited silicon-containing material and the oxide layer in a high density plasma. 
     According to another embodiment of the present invention, a method of forming a dielectric layer on a semiconductor device is disclosed. A semiconductor device having an oxide layer is provided. A silicon-containing material is vapor deposited over at least a portion of the semiconductor device. The deposited silicon-containing material and the oxide layer are converted into the dielectric layer by utilizing a high density plasma. 
     According to another embodiment of the present invention a semiconductor device is disclosed. The semiconductor device includes a substrate and a dielectric layer. The dielectric layer is formed over the substrate by converting vapor deposited silicon-containing material and a thin oxide layer using a high density plasma. 
     Other methods and devices are disclosed. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The following detailed description of the present invention can be best understood when read in conjunction with the accompanying drawings, where like structure is indicated with like reference numerals. 
     FIG. 1 illustrates a method for forming a dielectric layer according to one embodiment of the present invention. 
     FIGS. 2A,  2 B and  2 C illustrate a semiconductor device with a nitrided gate and its method of fabrication according to another embodiment of the present invention. 
     FIGS. 3A,  3 B and  3 C illustrate a semiconductor device and its method of fabrication according to another embodiment of the present invention. 
     FIGS. 4A,  4 B and  4 C illustrate a semiconductor device and its method of fabrication according to another embodiment of the present invention. 
     FIG. 5 illustrates a computer system that can use and be used with embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a method for forming a dielectric layer or ultra thin dielectric film according to one embodiment of the present invention. A substrate is provided at block  101 . The substrate may comprise one or more semiconductor layers or semiconductor structures which may define portions of a semiconductor device. A semiconductor device may comprise a transistor, capacitor, electrode, insulator or any of a variety of components commonly utilized in semiconductor structures. A silicon-containing material is vapor deposited over the substrate from a silicon source at block  102 . As is noted below, the silicon-containing material can be from a silazane or silane source such as hexamethyldisilazane (HMDS). 
     The dielectric layer or ultra thin dielectric film is formed by subjecting the deposited silicon-containing material to a high density plasma at a low temperature at block  103 . For the present invention, a low temperature is defined as a temperature less than 300° C. A “high density plasma” is a plasma containing a higher density of ions in comparison to a normal plasma. Normal plasma has an ion concentration in the range of 10 9  ions/cm 3  whereas high density plasma generally has a ion concentration of 10 11  to 10 12  ions/cm 3  (1000 times higher compared to normal plasma). Silicon atoms of the deposited material react with ions of the high density plasma. The high density plasma contains H 2 , NH 3 , N 2 , O 2 , O 3 , N 2 O or NO which are converted to ions or activated species by the high density plasma. 
     During the process of subjecting the deposited silicon-containing material to a high density plasma, the plasma can be remote or in contact with the wafer. The resulting film can be a nitride, oxynitride or oxide film with specific electrical properties, depending on the type of high density plasma used. Some examples of silicon-containing sources which may be used are hexamethyldisilazane (HMDS), tetramethyldisilazane, octamethylcyclotetrasilazine, hexamethylcyclotrisilazine, diethylaminotrimethylsilane and dimethylaminotrimethylsilane, however other silicon-containing sources may be used. 
     According to the remote plasma process of the present invention, the plasma is generated with microwaves or another form of conventional plasma generating energy. Specifically, a wafer or substrate is placed in a chamber. Gases such as H 2 , NH 3 , N 2 , O 2 , O 3 , N 2 O and NO are exposed to plasma generated outside of the chamber to create the activated species, such as H 2 , NH 3 , N 2 , O 2 , O 3 , N 2 O or NO ions. The plasma does not come into physical contact with the wafer or surface of the substrate which, in this case, is the silicon-containing material. The activated species are subsequently pumped into the chamber. This can reduce or prevent damage to the substrate or device. 
     Suitable remote plasma process parameters for a microwave plasma source include a power source of 500 W to 5 KW, a gas flow rate of 0-5000 cm 3 /min and a pressure of 100 mT to 50 T. 
     The contact plasma process is also referred to as a direct plasma process. The wafer containing the semiconductor device is placed in a chamber and the high density plasma is generated in the chamber, creating activated species. The plasma comes into direct contact with the wafer. Exemplary parameters include a power source of 100 W to 4 kW, gas flow rate of 0-5000 cm 3 /min and a chamber pressure of 500 mT to 5 T. 
     FIGS. 2A,  2 B and  2 C illustrate a semiconductor device with a nitrided gate according to another embodiment of the present invention. FIG. 2A shows the semiconductor device having a substrate  201  and a gate oxide  202  prior to depositing a silicon-containing material from a silicon source such as HMDS. The substrate  201  is of a semiconductor material such as, but not limited to silicon. The gate oxide  202  is formed over the substrate  201 . FIG. 2B shows the semiconductor device having the substrate  201 , the gate oxide  202  and a silicon containing material  203 , after depositing the the silicon containing material  203 . The silicon containing material  203  has been vapor deposited over the gate oxide  202 . FIG. 2C shows the semiconductor device after the silicon containing material  203  has been subjected to high density plasma (HDP)  204  and includes the substrate  201  and an oxynitrided gate  205 . The silicon containing material  203  can be subjected to the HDP remotely or directly. The gate oxide  202  and the silicon containing material  203  have been converted into the oxynitrided gate  205  by the HDP  204 . The HDP  204  can include any activated species of plasma that converts the silicon containing material  203  and gate oxide  202  into the oxynitrided gate  205 . Some examples of precursors used in such plasmas for nitridation are NH 3 , N 2 , and N 2 +H 2 . The oxynitrided gate  205  has a thickness of less than 30 Å and is comprised of Si 3 N 4  or SiO x N y . 
     FIGS. 3A,  3 B and  3 C illustrate a semiconductor device according to another embodiment of the present invention. FIG. 3A shows the semiconductor device having a substrate  301 , a lower electrode  302  and a native oxide  303  prior to depositing a silicon layer  304 . The substrate  301  is of a semiconductor material such as, but not limited to silicon. The lower electrode  302  is formed over the substrate  301 . Typically, the native oxide  303  is formed over the lower electrode  302 . The native oxide  303  naturally occurs on the lower electrode  302 . In other embodiments, an oxide layer can be grown or deposited instead of using a native oxide layer. FIG. 3B shows the semiconductor device having the substrate  301 , the lower electrode  302 , the native oxide  303  and a silicon layer  304 . The silicon layer  304  is typically vapor deposited over the native oxide  303  from a silicon source such as HMDS. FIG. 3C shows the semiconductor device after the silicon layer  304  has been subjected to HDP  306  and includes the substrate  301 , the lower electrode  302  and a dielectric layer  305 . The silicon layer  304  can be subjected to the HDP  306  remotely or directly. The native oxide  303  and the silicon layer  304  are converted into the oxynitrided gate  305  by the HDP  306  by causing silicon atoms of the silicon layer  304  to react with the native oxide and ions in the HDP  306 . The HDP  306  can include any activated species of plasma that converts the silicon layer  304  and gate oxide  303  into the dielectric layer  305 . Some examples of such plasmas are NH 3 , N 2 , and N 2 +H 2 . The dielectric layer  305  has a thickness of less than 30 Å. 
     FIGS. 4A,  4 B and  4 C illustrate a semiconductor device according to another embodiment of the present invention. FIG. 4A shows the semiconductor device having a substrate  401  and an oxide  402  prior to depositing a silicon-containing layer. The substrate  401  is of a semiconductor material such as, but not limited to silicon. The oxide  402  is formed over the substrate  401 . FIG. 4B shows the semiconductor device having the substrate  401 , the oxide  402  and a silicon-containing layer  403 , after depositing the silicon-containing layer  403 . The silicon-containing layer  403  is typically vapor deposited over the oxide  402 . FIG. 4C shows the semiconductor device after the silicon containing layer  403  has been subjected to HDP  404  and includes the substrate  401  and a dielectric layer  405 . The semiconductor device can be subjected to the HDP remotely or directly. The oxide  402  and silicon-containing layer  403  are converted into the&amp; dielectric layer  405  by the plasma  404 . The plasma  404  can include any activated species of plasma that converts the silicon-containing layer  403  and oxide  402  into the dielectric layer  405 . Some examples of such plasmas are NH 3 , N 2 , and N 2 +H 2 . The dielectric layer  405  can have a thickness of less than 30 Å. 
     FIG. 5 is an illustration of a computer system  512  that can use and be used with embodiments of the present invention. As will be appreciated by those skilled in the art, the computer system  512  would include ROM  514 , mass memory  516 , peripheral devices  518 , and I/O devices  520  in communication with a microprocessor  522  via a data bus  524  or another suitable data communication path. These devices can be fabricated according to the various embodiments of the present invention. For example, mass memory  516  can comprise memory cells having at least one ultra thin dielectric film formed according to one embodiment of the invention. 
     Dielectric layers or ultra thin dielectric films fabricated using the present invention can be used for a variety of purposes. Some examples follow, but embodiments of the present invention are not limited to these. A dielectric layer can be used as a cell dielectric material. A dielectric layer can be used as a single dielectric in a capacitor, transistor or antifuse application. A dielectric layer can be used to form composite dielectric in a multi dielectric stack type spacer, capacitor, transistor or anti-fuse application. A dielectric layer can be used to form a continuous low temperature barrier layer. A dielectric layer can be used for low temperature conditioning for advanced dielectrics such as Ta 2 O 5  and BST. A dielectric layer can be used for a low temperature post metal barrier layer or interconnect conditioning to reduce oxidation. 
     For the purposes of describing and defining the present invention, formation of a material “on” a substrate or layer refers to formation in contact with a surface of the substrate or layer. Formation “over” a substrate or layer refers to formation above or in contact with a surface of the substrate. Formation “in” a substrate or layer refers to formation of at least a portion of a structure in the interior of a substrate or layer. An “ultra-thin film” is a dielectric layer with a thickness not greater than 10 microns and uniformity within 20% of it&#39;s average value (Inventor: Please verify definition). 
     Having described the present invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the present invention defined in the appended claims.