Abstract:
A method of deposition of a transparent conductive film from a metallic target is presented. A method of forming a transparent conductive oxide film according to embodiments of the present invention include depositing the transparent conductive oxide film in a pulsed DC reactive ion process with substrate bias, and controlling at least one process parameter to affect at least one characteristic of the conductive oxide film. The resulting transparent oxide film, which in some embodiments can be an indium-tin oxide film, can exhibit a wide range of material properties depending on variations in process parameters. For example, varying the process parameters can result in a film with a wide range of resistive properties and surface smoothness of the film.

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Application 60/473,379, “Transparent Conductive Oxides from a Metallic Target,” by R. Ernest Demaray and Mukundan Narasimhan, filed on May 23, 2003, herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention is related to deposition of oxides on a substrate and, in particular, deposition of transparent conductive oxides. 
     2. Discussion of Related Art 
     Transparent conductive oxides have a wide variety of uses, including applications to solar cells, organic light emitting diodes (OLEDs), electric field devices, current devices (i.e. touch screens), energy efficient windows, conductive anti-reflective devices, electromagnetic interference shields, heaters, transparent electrodes, coatings for cathode ray tube (CRT) displays, to name only a few. Another important application is for touch sensitive MEMS devices, such as those used, for example, in fingerprint sensors and such. In many cases, the electrical properties of the conducting film is of great importance. 
     Specifically, for OLED applications, films deposited with current technologies are generally rough, resulting in stress risers and field concentration issues, that can cause leakage. Further, asperities in the resulting film can induce lifetime dependent defects in nearest neighbor films that can shorten device lifetimes. Additionally, the brightness of the emergent light from the OLED can be reduced. 
     Transparent conductive oxides have been deposited from ceramic targets by RF magnetron sputtering. However, the surface of properties of the resulting films often include nodules or asperites which can cause arcing, defects, surface roughness, and other deleterious effects in the resulting film. Additionally, ceramic targets tend to be more expensive to produce than metallic targets. 
     Previous attempts at deposition of transparent conductive oxides, for example indium tin oxide (ITO), with metallic targets have presented numerous problems, including small process windows, problems in process controllability, a disappearing anode effect, and particle deposition on the film. Such attempts have been abandoned. Deposition with ceramic targets has also been difficult, including problems with particles, nodule formation, and arching during deposition. In both cases, film smoothness has presented major difficulties. Additionally, control of film parameters such as, for example, resistivity and transparency has been difficult. 
     Therefore, there is need for cost effective deposition of smoother layers of transparent conductive oxides with greater control over layer properties such as resistivity and transparency. 
     SUMMARY 
     In accordance with the present invention, a method of depositing of a transparent conductive film from a metallic target is presented. A method of forming a transparent conductive oxide film according to embodiments of the present invention includes depositing the transparent conductive oxide film in a pulsed DC reactive ion process with substrate bias, and controlling at least one process parameter to provide at least one characteristic of the conductive oxide film at a particular value. 
     A method of depositing a transparent conductive oxide film on a substrate according to some embodiments of the invention, then, includes placing the substrate in a reaction chamber, adjusting power to a pulsed DC power supply coupled to a target in the reaction chamber, adjusting an RF bias power coupled to the substrate, adjusting gas flow into the reaction chamber, and providing a magnetic field at the target in order to direct deposition of the transparent conductive oxide film on the substrate in a pulsed-dc biased reactive-ion deposition process, wherein the transparent conductive oxide film has a particular characteristic. 
     The resulting transparent oxide film, which can be deposited according to some embodiments of the present invention, can be an indium-tin oxide (ITO) film. An ITO film can have a wide range of material properties depending on variations in process parameters. For example, varying the process parameters according to some embodiments of the present invention can result in a wide range of resistive properties and surface smoothness of the film. 
     These and other embodiments of the invention are further discussed below with reference to the following figures. 
    
    
     
       SHORT DESCRIPTION OF THE FIGURES 
         FIGS. 1A and 1B  illustrate a pulsed-DC biased reactive ion deposition apparatus that can be utilized in the methods of depositing according to the present invention. 
         FIG. 2  shows an example of a target that can be utilized in the reactor illustrated in  FIGS. 1A and 1B . 
         FIG. 3A  shows an Atomic Force Microscopy (AFM) image of an indium-tin-oxide (ITO) process according to some embodiments of the present invention. 
         FIG. 3B  shows an Atomic Force Microscopy (AFM) image of another ITO process deposited using a process according to some embodiments of the present invention. 
         FIG. 4  shows the variation of bulk resistivity of an ITO layer according to some embodiments of the present invention as a function of the oxygen flow for two different target powers before and after a 250° C. anneal in vacuum. 
         FIG. 5  shows the variation of the sheet resistance of an ITO layer according to some embodiments of the present invention as a function of the oxygen flow used for two different target powers before and after a 250° C. anneal in vacuum. 
         FIG. 6  shows the target current and voltage (min and max) as a function of oxygen flow. 
         FIG. 7  shows the thickness change in layers of ITO according to embodiments of the present invention as a function of oxygen flow. 
         FIG. 8  illustrates the relationship between oxygen flow and oxygen partial pressure for a metallic target. 
         FIGS. 9A-9D  illustrate the smoothness of transparent conductive oxides deposited with ceramic targets according to the present invention. 
     
    
    
     In the figures, elements having the same designation have the same or similar function. 
     DETAILED DESCRIPTION 
     Deposition of materials by pulsed-DC biased reactive ion deposition is described in U.S. patent application Ser. No. 10/101,863, entitled “Biased Pulse DC Reactive Sputtering of Oxide Films,” to Hongmei Zhang, et al., filed on Mar. 16, 2002. Preparation of targets is described in U.S. patent application Ser. No. 10/101,341, entitled “Rare-Earth Pre-Alloyed PVD Targets for Dielectric Planar Applications,” to Vassiliki Milonopoulou, et al., filed on Mar. 16, 2002. U.S. patent application Ser. No. 10/101,863 and U.S. patent application Ser. No. 10/101,341 are each assigned to the same assignee as is the present disclosure and each is incorporated herein in their entirety. Deposition of oxide materials has also been described in U.S. Pat. No. 6,506,289, which is also herein incorporated by reference in its entirety. Transparent oxide films are deposited utilizing processes similar to those specifically described in U.S. Pat. No. 6,506,289 and U.S. application Ser. No. 10/101,863. 
       FIG. 1A  shows a schematic of a reactor apparatus  10  for sputtering material from a target  12  according to the present invention. In some embodiments, apparatus  10  may, for example, be adapted from an AKT-1600 PVD (400×500 mm substrate size) system from Applied Komatsu or an AKT-4300 (600×720 mm substrate size) system from Applied Komatsu, Santa Clara, Calif. The AKT-1600 reactor, for example, has three deposition chambers connected by a vacuum transport chamber. These Komatsu reactors can be modified such that pulsed DC power is supplied to the target and RF power is supplied to the substrate during deposition of a material film. 
     Apparatus  10  includes target  12  which is electrically coupled through a filter  15  to a pulsed DC power supply  14 . In some embodiments, target  12  is a wide area sputter source target, which provides material to be deposited on a substrate  16 . Substrate  16  is positioned parallel to and opposite target  12 . Target  12  functions as a cathode when power is applied to it and is equivalently termed a cathode. Application of power to target  12  creates a plasma  53 . Substrate  16  is capacitively coupled to an electrode  17  through an insulator  54 . Electrode  17  can be coupled to an RF power supply  18 . A magnet  20  is scanned across the top of target  12 . 
     For pulsed reactive dc magnetron sputtering, as performed by apparatus  10 , the polarity of the power supplied to target  12  by power supply  14  oscillates between negative and positive potentials. During the positive period, the insulating layer on the surface of target  12  is discharged and arcing is prevented. To obtain arc free deposition, the pulsing frequency exceeds a critical frequency that can depend on target material, cathode current and reverse time. High quality oxide films can be made using reactive pulse DC magnetron sputtering as shown in apparatus  10 . 
     Pulsed DC power supply  14  can be any pulsed DC power supply, for example an AE Pinnacle plus 10K by Advanced Energy, Inc. With this DC power supply, up to 10 kW of pulsed DC power can be supplied at a frequency of between 0 and 350 KHz. The reverse voltage can be 10% of the negative target voltage. Utilization of other power supplies can lead to different power characteristics, frequency characteristics and reverse voltage percentages. The reverse time on this embodiment of power supply  14  can be adjusted between 0 and 5 μs. 
     Filter  15  prevents the bias power from power supply  18  from coupling into pulsed DC power supply  14 . In some embodiments, power supply  18  can be a 2 MHz RF power supply, for example a Nova-25 power supply made by ENI, Colorado Springs, Co. 
     In some embodiments, filter  15  can be a 2 MHz sinusoidal band rejection filter. In some embodiments, the band width of the filter can be approximately 100 kHz. Filter  15 , therefore, prevents the 2 MHz power from the bias to substrate  16  from damaging power supply  18 . 
     However, both RF and pulsed DC deposited films are not fully dense and may have columnar structures. Columnar structures can be detrimental to thin film applications. By applying a RF bias on wafer  16  during deposition, the deposited film can be densified by energetic ion bombardment and the columnar structure can be substantially eliminated. 
     In the AKT-1600 based system, for example, target  12  can have an active size of about 675.70×582.48 by 4 mm in order to deposit films on substrate  16  that have dimension about 400×500 mm. The temperature of substrate  16  can be held at between −50° C. and 500° C. The distance between target  12  and substrate  16  can be between about 3 and about 9 cm. Process gas can be inserted into the chamber of apparatus  10  at a rate up to about 200 sccm while the pressure in the chamber of apparatus  10  can be held at between about 0.7 and 6 millitorr. Magnet  20  provides a magnetic field of strength between about 400 and about 600 Gauss directed in the plane of target  12  and is moved across target  12  at a rate of less than about 20-30 sec/scan. In some embodiments utilizing the AKT 1600 reactor, magnet  20  can be a race-track shaped magnet with dimensions about 150 mm by 600 mm. 
       FIG. 2  illustrates an example of target  12 . A film deposited on a substrate positioned on carrier sheet  17  directly opposed to region  52  of target  12  has good thickness uniformity. Region  52  is the region shown in  FIG. 1B  that is exposed to a uniform plasma condition. In some implementations, carrier  17  can be coextensive with region  52 . Region  24  shown in  FIG. 2  indicates the area below which both physically and chemically uniform deposition can be achieved, for example where physical and chemical uniformity provide refractive index uniformity.  FIG. 2  indicates region  52  of target  12  that provides thickness uniformity is, in general, larger than region  24  of target  12  providing thickness and chemical uniformity. In optimized processes, however, regions  52  and  24  may be coextensive. 
     In some embodiments, magnet  20  extends beyond area  52  in one direction, for example the Y direction in  FIG. 2 , so that scanning is necessary in only one direction, for example the X direction, to provide a time averaged uniform magnetic field. As shown in  FIGS. 1A and 1B , magnet  20  can be scanned over the entire extent of target  12 , which is larger than region  52  of uniform sputter erosion. Magnet  20  is moved in a plane parallel to the plane of target  12 . 
     The combination of a uniform target  12  with a target area  52  larger than the area of substrate  16  can provide films of highly uniform thickness. Further, the material properties of the film deposited can be highly uniform. The conditions of sputtering at the target surface, such as the uniformity of erosion, the average temperature of the plasma at the target surface and the equilibration of the target surface with the gas phase ambient of the process are uniform over a region which is greater than or equal to the region to be coated with a uniform film thickness. In addition, the region of uniform film thickness is greater than or equal to the region of the film which is to have highly uniform optical properties such as index of refraction, density, transmission or absorptivity. 
     Target  12  can be formed of any materials. Typically metallic materials, for example, include combinations of In and Sn. Therefore, in some embodiments, target  12  includes a metallic target material formed from intermetallic compounds of optical elements such as Si, Al, Er and Yb. Additionally, target  12  can be formed, for example, from materials such as La, Yt, Ag, Au, and Eu. To form optically active films on substrate  16 , target  12  can include rare-earth ions. In some embodiments of target  12  with rare earth ions, the rare earth ions can be pre-alloyed with the metallic host components to form intermetallics. See U.S. application Ser. No. 10/101,341. Typical ceramic target materials include alumina, silica, alumina silicates, and other such materials. 
     In some embodiments of the invention, material tiles are formed. These tiles can be mounted on a backing plate to form a target for apparatus  10 . A wide area sputter cathode target can be formed from a close packed array of smaller tiles. Target  12 , therefore, may include any number of tiles, for example between 2 to 20 individual tiles. Tiles can be finished to a size so as to provide a margin of non-contact, tile to tile, less than about 0.010″ to about 0.020″ or less than half a millimeter so as to eliminate plasma processes that may occur between adjacent ones of tiles  30 . The distance between tiles of target  12  and the dark space anode or ground shield  19  in  FIG. 1B  can be somewhat larger so as to provide non contact assembly or to provide for thermal expansion tolerance during process chamber conditioning or operation. 
     As shown in  FIG. 1B , a uniform plasma condition can be created in the region between target  12  and substrate  16  in a region overlying substrate  16 . A plasma  53  can be created in region  51 , which extends under the entire target  12 . A central region  52  of target  12  can experience a condition of uniform sputter erosion. As discussed further below, a layer deposited on a substrate placed anywhere below central region  52  can then be uniform in thickness and other properties (i.e., dielectric, optical index, or material concentrations). In addition, region  52  in which deposition provides uniformity of deposited film can be larger than the area in which the deposition provides a film with uniform physical or optical properties such as chemical composition or index of refraction. In some embodiments, target  12  is substantially planar in order to provide uniformity in the film deposited on substrate  16 . In practice, planarity of target  12  can mean that all portions of the target surface in region  52  are within a few millimeters of a planar surface, and can be typically within 0.5 mm of a planar surface. 
     Reactive gases that provide a constant supply of ionic oxygen to keep the target surface oxidized can be provided to expand the process window. Some examples of the gases that can be utilized for controlling surface oxidation are CO 2 , water vapor, hydrogen, N 2 O, fluorine, helium, and cesium. Additionally, a feedback control system can be incorporated to control the oxygen partial pressure in the reactive chamber. Therefore, a wide range of oxygen flow rates can be controlled to keep a steady oxygen partial pressure in the resulting plasma. Other types of control-systems such as target voltage control and optical plasma emission control systems can also be utilized to control the surface oxidation of the target. As shown in  FIG. 1A , power to target  12  can be controlled in a feedback loop at supply  14 . Further, oxygen partial pressure controller  24  can control either oxygen or argon partial pressures in plasma  53 . 
     In some embodiments, transparent conductive oxides can be deposited on various substrates utilizing an inidium-tin (In/Sn) metallic target. A series of depositions on glass in accordance with the present invention is illustrated in Table I. The parameters in the process column of Table I are in the format (pulsed DC power/RF bias power/pulsing frequency/reverse time/deposition time/Ar flow (sccms)/O 2  flow (sccms)). An indium-tin (In/Sn: 90%/10% by weight) target using a reactive-pulsed DC (RPDC) process such as that described in U.S. application Ser. No. 10/101,863 was utilized. A power supply with 2 MHz RF bias applied to substrate  16  was utilized in the process. Along with the process parameters for each of the separate depositions, each defined by a “Slot” number in the first column, the target voltage, and target current ranges for each of the depositions is also listed. 
     Table 2 shows the results obtained by using the process parameters in Table 1. The results include the sheet resistance, thickness, bulk resistivity, and refractive indices of the resulting films. Again, the first column indicates the slot number of the deposition. The process for each slot number is reiterated in column 2 of Table 2. The sheet resistance of selected ones of the films resulting from the deposition is listed in the third column and the uniformity of the sheet resistance is indicated in the fourth column. The thickness of the film and its uniformity of each of the films deposited by the indicated process is indicated in the fifth and sixth columns. The bulk resistance of selected ones of the films, ρ, is also indicated. Additionally, the refractive index taken at 632 nm is indicated along with the film uniformity of that index. The comments section of Table 2 indicates whether the resulting film is transparent, translucent, or metallic in character. 
       FIG. 3A  shows the Atomic Force Microscopy (AFM) image of an ITO film produced by the process identified in slot #5 in tables 1 and 2. That process, with particularly low oxygen flow rates (24 sccm), produced a rough film with an Ra of about 70 Å and an Rms of about 90 Å. The film also appears to be metallic with this particular oxygen flow and the film roughness is high. Such a film could be applicable to large surface area requirements, for example solar cell applications. Wile not being limited by any particular theory, it is suspected that the roughness of this film reflects the sub-stoichiometric nature of the film caused by insufficient oxygen flow in the plasma. As can be seen in  FIG. 3B , where the oxygen flow during deposition has been significantly increased to about 36 sccm, the film is smooth. 
       FIG. 3B  shows an Atomic Force Microscopy (AFM) image of an ITO film deposited using the process described in slot #19 of Tables 1 and 2. In that process, the oxygen flow rate is increased to 36 sccm. The film appears to be transparent and conductive and the surface roughness is ˜6 Å Ra and Rms of about 13 Å, which is acceptable for OLED requirements. As can be seen from  FIGS. 3A and 3B , variation in oxygen partial pressure (as indicated by increased flow rate) has a large influence on the characteristics of the resulting deposited film. 
     The resistivity of the film layer and the smoothness of the film layer can be related. In general, the higher the resistivity of the film layer, the smoother the film layer.  FIG. 4  shows the variation of bulk resistivity of the ITO as a function of the oxygen flow rate used for two different target powers before and after a 250° C. anneal in vacuum. The bulk resistivity of the film exhibits a sudden transition downward as the oxygen flow rate is lowered. This transition occurs when the target surface becomes metallic from being poisoned with oxygen. The data utilized to form the graph shown in  FIG. 4  has been taken from Tables 1 and 2. 
       FIG. 5  shows the variation of the sheet resistance of an ITO film as function of the O 2  flow used for two different target powers before and after a 250 C anneal in vacuum. As shown in  FIG. 5 , the sheet resistance follows similar trends as the bulk resistivity of the film. 
       FIG. 6  shows the target current and voltage (min and max) as a function of the oxygen flow rate. The target voltage increases as the oxygen flow rate is lowered. It could be seen here that at a 40 sccm oxygen flow rate through repeated depositions, the target voltage is not constant. This illustrates the utility of a target voltage feedback control system that adjusts the power supplied to target  12  to hold the target voltage constant. Therefore, as shown in  FIG. 1A , PDC power  14  can include feedack loop to control the voltage on target  12 . 
       FIG. 7  shows the thickness change of a resulting film as a function of oxygen flow rate in sccm. The thickness of the film increases as the oxygen flow decreases but this could make opaque metallic films and so choosing the correct oxygen flow and utilizing an oxygen flow feedback control system to control material characteristics such as, for example, transparency or conductivity can be desirable. 
     In some embodiments, instead of oxygen flow rate, oxygen partial pressure can be controlled with a feedback system  24  (see  FIG. 1A ). Controlling the oxygen partial pressure can provide better control over the oxygen content of the plasma, and therefore the oxygen content of the resulting films, and allows better control over the film characteristics.  FIG. 8  illustrates the relationship between the flow rate and partial pressure. As can be seen from  FIG. 8 , in order to reach the saturated region (e.g., when target  12  is completely poisoned with oxygen), no increase in flow rate is required. In some embodiments, reactor  10  can include a partial pressure feedback loop controller  24  that controls the oxygen flow in order to maintain a desired partial pressure of oxygen in the plasma. Such a controller can be the IRESS system, that can be purchased from Advanced Energy, Inc., Ft. Collins, Colo. It has been found that film parameters such as resistivity, smoothness, and transparency can be highly dependent on oxygen partial pressures, and therefore these characteristics of the resulting deposited layer can be controlled by adjusting the oxygen partial pressures. 
     Some embodiments of the present invention can be deposited with ceramic targets. An example target is an ITO (In/Sn 90/10) ceramic target can be utilized. Table 3 illustrates some example processes for deposition of ITO utilizing a ceramic target according to the present invention. Bulk resistivity, sheet resistance, resistance, thicknesses, deposition rates, and index of refraction of the resulting films are shown along with the process parameters utilized in the deposition.  FIG. 9A  shows an AFM depiction of a transparent conductive oxide film corresponding to run #10 in Table 3.  FIG. 9B  shows an AFM depiction of a transparent conductive oxide film corresponding to run #14 in Table 3.  FIG. 9C  shows an AFM depiction of a transparent conductive oxide film corresponding to run #16 in Table 3.  FIG. 9D  shows an AFM depiction of a transparent conductive oxide film layer corresponding to run #6 in Table 3. 
       FIGS. 9A through 9D  illustrate the roughnesses of selective depositions of ITO deposited utilizing the ceramic target. In  FIG. 9A , the roughest surface shown, the film was deposited using 3 kW RF power, 100 W bias, 3 sccm O 2  and 60 sccm Ar at a temperature of 280° C. The layer grew to a thickness of 1200 Å in 100 seconds of deposition time and exhibited a sheet resistance of 51 ohms/sq. The roughness illustrated in  FIG. 9A  is characterized by an Ra=2.3 nm and R MS  of 21 nm. 
     The ITO film shown in  FIG. 9B  was deposited using 3 kW RF power, 300 W bias, 3 sccm O 2  and 60 sccm Ar at a temperature of 280° C. The layer illustrated in  FIG. 9B  grew to a thickness of 1199 Å in 100 sec. The layer in  FIG. 9B  exhibited a sheet resistance of 39 ohms/sq. The roughness illustrated in  FIG. 9B  is characterized by an Ra=1.1 nm and Rmax of 13 nm. 
     The ITO film shown in  FIG. 9C  was deposited using 3 kW RF power, 300 W bias, 3 sccm O 2 , 30 sccm Ar at a temperature of 280° C. The layer grew to a thickness of 1227 Å in 100 seconds of deposition time and exhibited a sheet resistance of 57 ohms/sq. The roughness illustrated in  FIG. 9C  can be characterized by an Ra=0.88 nm and a Rmax of 19.8 nm. 
       FIG. 9D  was deposited using 1.5 kW RF power, 300 W bias, 0 sccm O 2 , 30 sccm Ar at a temperature of 280 C. The layer grew to a thickness of 580 Å in 100 seconds of deposition time and exhibited a sheet resistance of 106 ohms/sq. The roughness illustrated in  FIG. 9C  can be characterized by an Ra=0.45 nm and an Rmax of 4.6 mm. 
     Utilizing the example depositions described herein, the roughness and resistivity of a transparent oxide film can be tuned to particular applications. In general, particularly high resistivities can be obtained, which are useful for touch sensitive devices. As shown in Table 3, the sheet resistance ranged from about 39 Ω/sq for trial #14 to a high of 12,284 Ω/sq for trial #1. Careful variation of the process parameters, therefore, allow control of sheet resistance over an extremely broad range. Low resistivities can be obtained by adjusting the process parameters for uses in devices such as OLEDS and MEMS display devices. As is illustrated in Table 3, the bulk resistivity can be controlled to be between about 2E-4 micro-ohms-cm to about 0.1 micro-ohms-cm. Additionally, other parameters such as refractive index and transparency of the film can be controlled. 
     Further, deposition of transparent conductive oxide layers, for example ITO, can be doped with rare-earth ions, for example erbium or cerium, can be utilized to form color-conversion layers and light-emission sources. In some embodiments, a rare-earth doped target can be made in a single piece to insure uniformity of doping. Co-doping can be accomplished in the target. 
     Similar processes for other metallic conductive oxides can also be developed. For example, deposition of zinc oxide films. Further, as can be seen in the examples shown in Table 3, low temperature depositions can be performed. For example, transparent conductive oxides according to the present invention can be deposited at temperatures as low as about 100° C. Such low temperature depositions can be important for depositions on temperature sensitive materials such as plastics. 
     Other thin film layers according to the present invention include deposition of other metal oxides to form conducting and semi-conducting films. Thin films formed according to the present invention can be utilized in many devices, including, but not limited to, displays, photovoltaics, photosensors, touchscreens, and EMI shielding. 
     Embodiments of the invention disclosed here are examples only and are not intended to be limiting. Further, one skilled in the art will recognize variations in the embodiments of the invention described herein which are intended to be included within the scope and spirit of the present disclosure. As such, the invention is limited only by the following claims. 
     
       
         
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                   
                 Target Voltage 
                 Target Current 
               
               
                   
                 (V) 
                 (Amps) 
               
             
          
           
               
                 Slot # 
                 Process 
                 Min 
                 Max 
                 Mix 
                 Max 
               
               
                   
               
             
          
           
               
                 14 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 244 
                 252 
                 5.94 
                 6.14 
               
               
                   
                 300 s/20Ar/80O 2   
                   
                   
                   
                   
               
               
                 15 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 254 
                 263 
                 5.7 
                 5.9 
               
               
                   
                 300 s/20Ar/40O 2   
                   
                   
                   
                   
               
               
                 17 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 252 
                 260 
                 5.76 
                 5.96 
               
               
                   
                 300 s/20Ar/40O 2   
                   
                   
                   
                   
               
               
                 19 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 254 
                 263 
                 5.72 
                 5.92 
               
               
                   
                 300 s/20Ar/36O 2   
                   
                   
                   
                   
               
               
                 21 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 255 
                 268 
                 5.76 
                 5.9 
               
               
                   
                 300 s/20Ar/30O 2   
                   
                   
                   
                   
               
               
                  1 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 224 
                 233 
                 4.32 
                 4.5 
               
               
                   
                 300 s/20Ar/80O 2   
                   
                   
                   
                   
               
               
                  2 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 231 
                 243 
                 4.12 
                 4.3 
               
               
                   
                 300 s/20Ar/36O 2   
                   
                   
                   
                   
               
               
                  3 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 232 
                 242 
                 4.12 
                 4.28 
               
               
                   
                 300 s/20Ar/32O 2   
                   
                   
                   
                   
               
               
                  4 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 237 
                 243 
                 4.1 
                 4.22 
               
               
                   
                 300 s/20Ar/28O 2   
                   
                   
                   
                   
               
               
                  5 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 233 
                 243 
                 4.1 
                 4.34 
               
               
                   
                 300 s/20Ar/24O 2   
                   
                   
                   
                   
               
               
                  6 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 231 
                 245 
                 4.12 
                 4.3 
               
               
                   
                 300 s/20Ar/28O 2   
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE II 
               
               
                   
               
               
                   
                   
                 Rs 
                 Rs 
                   
                 Th 
                   
                   
                   
                   
               
               
                   
                   
                 (Ohms/ 
                 unif 
                 Th 
                 std 
                 Bulk Rho 
                   
                   
                   
               
               
                 Slot # 
                 Process 
                 Sq) 
                 % 
                 (nm) 
                 1 sig 
                 (μOhm-cm) 
                 R.I (@632 nm) 
                 R.I Unif (%) 
                 Comments 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 14 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                   
                   
                 38.59 
                 0.16 
                   
                 1.980758 
                 0.000005 
                 transparent 
               
               
                   
                 300 s/20Ar/80O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 15 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 94112 
                 2 
                 57.28 
                 0.51 
                 539073.5 
                 1.951452 
                 0.029342 
                 translucent 
               
               
                   
                 300 s/20Ar/40O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 17 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 33927 
                 60.282 
                 58.48 
                 1.37 
                 198405.1 
                 1.936166 
                 0.040957 
                 translucent 
               
               
                   
                 300 s/20Ar/40O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 19 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 7335.32 
                 72.49 
                 67.75 
                 1.03 
                 49696.8 
                 1.980746 
                 0.000018 
                 translucent 
               
               
                   
                 300 s/20Ar/36O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 21 
                 1.5 kw/100 w/200 khz/2.2 μs/ 
                 22.3507 
                 2.995 
                 80 
                   
                  178.8 
                   
                   
                 metallic 
               
               
                   
                 300 s/20Ar/30O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                  1 
                 1 kw/100 w/200 khz/2.2 μs/ 
                   
                   
                 26.69 
                 0.32 
                   
                 1.980326 
                 0.00096  
                 transparent 
               
               
                   
                 300 s/20Ar/80O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                  2 
                 1 kw/100 w/200 khz/2.2 μs/ 
                   
                   
                 36.4 
                 0.13 
                   
                 1.980756 
                 0.000003 
                 transparent 
               
               
                   
                 300 s/20Ar/36O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                  3 
                 1 kw/100 w/200 khz/2.2 μs/ 
                   
                   
                 39.3 
                 0.15 
                   
                 1.980761 
                 0     
                 transparent 
               
               
                   
                 300 s/20Ar/32O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                  4 
                 1 kw/100 w/200 khz/2.2 μs/ 
                   
                   
                 44.02 
                 0.24 
                   
                 1.98076  
                 0.000001 
                 transparent 
               
               
                   
                 300 s/20Ar/28O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                  5 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 58.1031 
                 7.467 
                 50 
                   
                  290.5 
                   
                   
                 metallic 
               
               
                   
                 300 s/20Ar/24O2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                  6 
                 1 kw/100 w/200 khz/2.2 μs/ 
                 58.0992 
                 10.566 
                 45 
                   
                  261.4 
                   
                   
                 metallic 
               
               
                   
                 300 s/20Ar/28O2 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE III 
               
               
                   
               
               
                   
                   
                 Target 
                   
                   
                   
                   
                   
                 Rs 
                   
                 Thick- 
                   
                   
                   
                   
               
               
                   
                 Run 
                 Power 
                 Bias/ 
                   
                   
                 T 
                 Rs 
                 (non- 
                 Bulk Rho 
                 ness 
                   
                 DepRate 
                   
                   
               
               
                 Trial 
                 (sec) 
                 (kW) 
                 W 
                 O2 
                 Ar 
                 (° C.) 
                 (Ohms/Sq) 
                 unif) 
                 (uOhmcm) 
                 (Å) 
                 n 
                 (A/sec) 
                 Target/V 
                 Target/I 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 14 
                 100 
                 3 
                 300 
                 3 
                 60 
                 280 
                 38.69 
                 4.07% 
                 4.64E−04 
                 1200 
                 1.864 
                 12 
                   
                   
               
               
                 16 
                 100 
                 3 
                 300 
                 3 
                 30 
                 280 
                 56.90 
                 7.94% 
                 6.98E−04 
                 1227 
                 1.888 
                 12.27 
                 288-308 
                  9.86-10.42 
               
               
                 10 
                 100 
                 3 
                 100 
                 3 
                 60 
                 280 
                 50.98 
                 11.89% 
                 6.25E−04 
                 1225 
                 1.933 
                 12.25 
                 265-275 
                 10.92-11.36 
               
               
                 4 
                 100 
                 1.5 
                 100 
                 3 
                 30 
                 280 
                 383.62 
                 21.72% 
                 2.09E−03 
                 543.9 
                 2.016 
                 5.439 
                 238-251 
                 5.98-6.32 
               
               
                 8 
                 100 
                 1.5 
                 300 
                 3 
                 30 
                 280 
                 504.02 
                 7.23% 
                 2.44E−03 
                 483.5 
                 2.082 
                 4.835 
                 239-250 
                 5.98-6.33 
               
               
                 2 
                 100 
                 1.5 
                 100 
                 3 
                 30 
                 280 
                 402.52 
                 26.80% 
                 2.10E−03 
                 520.7 
                 2.056 
                 5.207 
                 225-239 
                 6.46-6.68 
               
               
                 6 
                 100 
                 1.5 
                 300 
                 0 
                 30 
                 280 
                 106.21 
                 6.12% 
                 6.17E−04 
                 580.5 
                 1.945 
                 5.805 
                 237-250 
                 5.98-6.38 
               
               
                 12 
                 100 
                 3 
                 100 
                 4 
                 30 
                 280 
                 374.34 
                 19.43% 
                 4.18E−03 
                 1116 
                 1.917 
                 11.16 
                 285-300 
                  9.98-10.52 
               
               
                 15 
                 100 
                 3 
                 300 
                 4 
                 30 
                 100 
                 6264.69 
                 58.18% 
                 6.81E−02 
                 1087 
                 1.897 
                 10.87 
                 282-304 
                 10.00-10.62 
               
               
                 7 
                 100 
                 1.5 
                 200 
                 4 
                 30 
                 100 
                 7509.45 
                 44.14% 
                 2.95E−02 
                 392.3 
                 2.149 
                 3.923 
                 237-250 
                 6.02-632  
               
               
                 1 
                 100 
                 1.5 
                 100 
                 4 
                 30 
                 100 
                 12284.82 
                 112.55% 
                 4.78E−02 
                 389.1 
                 2.236 
                 3.891 
                 238-250 
                 6.04-632  
               
               
                 11 
                 100 
                 3 
                 100 
                 3 
                 60 
                 100 
                 631.77 
                 49.40% 
                 7.30E−03 
                 1155 
                 1.958 
                 11.55 
                 266-273 
                 10.96-11.38 
               
               
                 9 
                 100 
                 3 
                 100 
                 0 
                 30 
                 100 
                 43.78 
                 7.47% 
                 5.55E−04 
                 1268 
                 1.945 
                 12.68 
                 288-307 
                  9.78-10.42 
               
               
                 5 
                 100 
                 1.5 
                 200 
                 3 
                 60 
                 100 
                 1293.53 
                 14.82% 
                 5.88E−03 
                 454.8 
                 2.149 
                 4.548 
                 225-235 
                 6.46-6.68 
               
               
                 3 
                 100 
                 1.5 
                 100 
                 4 
                 60 
                 100 
                 4154.43 
                 28.25% 
                 1.78E−02 
                 428.8 
                 2.211 
                 4.288 
                 226-235 
                 6.44-6.64 
               
               
                 13 
                 100 
                 3 
                 200 
                 0 
                 60 
                 100 
                 49.05 
                 7.24% 
                 6.16E−04 
                 1256 
                 1.913 
                 12.56 
                 264-275 
                 10.96-11.38 
               
               
                 18 
                 100 
                 2.25 
                 100 
                 3 
                 30 
                 100 
                 1476.79 
                 21.54% 
                 1.10E−02 
                 744.5 
                 2.044 
                 7.445 
                 263-277 
                 8.08-8.56 
               
               
                 17 
                 100 
                 1.5 
                 150 
                 0 
                 60 
                 100 
                 157.23 
                 8.83% 
                 9.91E−04 
                 630.5 
                 1.931 
                 6.305 
                 225-231 
                 6.48-6.74 
               
               
                 19 
                 100 
                 2.25 
                 150 
                 3 
                 60 
                 100 
                 526.72 
                 13.01% 
                 4.29E−03 
                 814.2 
                 2.021 
                 8.142 
                 247-255 
                 8.78-9.14