Abstract:
chemical vapor deposition (CVD) equipment and a CVD method using the same enhance production yield by preventing non-reacted gas from agglomerating on a substrate before the plasma reaction is induced. This source gas is composed of first and second gases. Only the first gas is initially supplied into the process chamber of the CVD equipment. Then the second source gas and the first source gas are supplied as a mixture but at this time are dumped to the exhaust section of the CVD equipment so as to bypass the process chamber. After a delay, the first source gas and the second source gas are supplied together as source gas into the process chamber and at this time, an RF power is applied to the source gas to induce the plasma reaction that forms a film on a wafer disposed inside the chamber. Thus, non-reacted gas is prevented from agglomerating on the substrate. As a result, the film has a high degree of uniformity.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to semiconductor fabrication equipment. More particularly, the present invention relates to chemical vapor deposition (CVD) equipment and to a CVD method using the same for forming a thin film on a wafer or the like.  
         [0003]     2. Description of the Related Art  
         [0004]     Recently, the line widths of the integrated circuits of semiconductor chips are gradually being reduced to increase the speed at which the semiconductor chips operate and to increase the storage capacity per unit area of the chips. Furthermore, semiconductor devices themselves, such as the transistors integrated on a semiconductor wafer, have been scaled down to dimensions on the order of a half micron or less.  
         [0005]     The processes used to fabricate a semiconductor device include a deposition process, a photolithography process, an etch process, and a diffusion process. These processes are repeatedly performed several or tens of times on a wafer to fabricate at least one semiconductor device. In particular, the deposition process is performed to form a thin film on a wafer, and the reproducibility of the deposition process is thus essential in fabricating reliable semiconductor devices. Such a deposition process may be performed using a sol-gel method, a sputtering method, an electro-plating method, an evaporation method, a chemical vapor deposition (CVD) method, a molecular beam epitaxy (MBE) method, or an atomic layer deposition (ALD) method.  
         [0006]     The CVD method is most widely used because of its ability to form a thin film on a wafer that is much more uniform than those which can be formed by other deposition methods. The CVD method may be classified, according to a processing condition under which the method is carried out, as low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), low temperature chemical vapor deposition (LTCVD), or plasma enhanced chemical vapor deposition (PECVD).  
         [0007]     For example, PECVD is a method used to form a dielectric layer on a wafer. In PECVD, a chemical reaction of gases is produced via an electric discharge. A product of the chemical reaction is a deposited on the wafer. In a conventional PECVD process, a plurality of wafers are loaded into a processing chamber of a plasma CVD apparatus, and layers are respectively formed all at once on the wafers by PECVD. Recently, however, the diameter of a typical wafer has become quite large, and the semiconductor devices to be formed thereon are to be highly-integrated. Accordingly, in a recent PECVD method, only one wafer at a time is loaded into the processing chamber of the plasma CVD apparatus, and a PECVD process is performed on the wafer. Then, a cleaning and purging process is performed to remove gases remaining inside the processing chamber of the plasma CVD apparatus and to remove a by-product of the chemical reaction from surfaces inside the processing chamber.  
         [0008]     One example of CVD equipment for forming an interlayer insulating layer, such as a silicon oxide layer, on a wafer is disclosed in U.S. Pat. No. 6,009,827. Such conventional CVD equipment and a conventional CVD method using the same will be described below with reference to  FIGS. 1 and 2 .  
         [0009]     Referring first to  FIG. 1 , the conventional CVD equipment includes a source gas supply section  10  that provides a supply of source gas, a purge gas supply section  40  that provides a source of purge gas, a process chamber  20  in which a thin film is formed on a wafer, a supply line  12  connecting the source gas supply section  10  and the purge gas supply section  40  to the chamber  20 , and an exhaust section  30  for evacuating the process chamber  20 . The source gas supply section  10  includes an oxygen gas tank  15   a  for storing oxygen, a TEOS gas tank for storing TEOS gas, a first flow control valve  16   a  and a second flow control valve  16   b  for controlling the flow rates of the oxygen gas and the TEOS gas from the oxygen gas and TEOS gas tanks, respectively, and a first shutoff valve  18   a  and a second shutoff valve  18   b  that can be opened and closed to selectively supply the oxygen gas and the TEOS gas into the process chamber  20  via the supply line  12 . Similarly, the purge gas supply section  40  includes a purge gas tank for storing a purge gas, a third flow control valve  16   c  for controlling the flow rate of the purge gas from the purge gas tank, and a third shut off valve  18   c  that can be opened and closed to selectively supply the purge gas into the process chamber  20  via the supply line  12 .  
         [0010]     Furthermore, the CVD equipment includes a chuck  24  disposed at the bottom of the process chamber  20 , a shower head  28  disposed at the top of the process chamber  20  opposite the chuck  24 , and at least one plasma electrode  26  disposed over the shower head  28  (electrode  26   a ) or below the chuck  24  (electrode  26   b ). The wafer  22  on which the thin film is to be formed is supported and fixed in place by the chuck  24 . The shower head  26  receives gas from the supply line  12  and sprays the gas, e.g., the oxygen gas and the TEOS gas, uniformly over the wafer  22 . The at least one electrode  26   a ,  26   b  induces a reaction in a high-temperature state between the oxygen gas and the TEOS gas. To this end, an external power source applies an RF power to the at least one plasma electrode  26   a ,  26   b . As a result, a silicon oxide layer having a high degree of uniformity is formed on the wafer  22 .  
         [0011]     The exhaust section  30  includes an exhaust line  32  communicating with the process chamber  20   a , a vacuum pump system  34  connected to the exhaust line  32  for pumping air/gas from the process chamber  20 , and a pressure control valve  36  disposed in the exhaust line  32  for controlling the amount of air pumped by the vacuum pump system  34  from the chamber  20  to maintain a vacuum inside the process chamber  20 .  
         [0012]     More specifically, the vacuum pump system  34  gradually pumps the air out of the process chamber  20 . The system  34  includes a high vacuum pump  34   a  such as a turbo pump or a diffusion pump and a low vacuum pump  34   b  connected in series in the exhaust line  32  downstream of the pressure control valve  36 . Also, a dummy exhaust line  32   a  branches from the exhaust line  32  at a location between the pressure control valve  36  and the high vacuum pump  34   a , and rejoins the exhaust line  32  downstream of the high vacuum pump  34   a . A luffing valve  38   a  is disposed in the dummy exhaust line  32   a . A fore line valve  38  is disposed in the exhaust line  32  between the high vacuum pump  34   a  and the fore (upstream) end of the low vacuum pump  34   b . The exhaust section  30  further includes a scrubber (not shown) for purifying the gas exhausted from the chamber  20  before the gas is vented to the atmosphere.  
         [0013]     A CVD method using the conventional CVD equipment having the structure described above will be explained with reference to  FIG. 2 .  
         [0014]     The conventional CVD method includes loading the wafer  22  into the process chamber  20 , and pumping air from inside the process chamber  20  to create a vacuum in the chamber  20  (s 10 ). At this time, the air inside the process chamber  20  is in a higher vacuum state than that prevailing during the subsequent deposition process. That is, the air is pumped from the process chamber  20  at a relatively high rate to remove foreign contaminants from the process chamber  20  while the wafer  22  is being loaded into the chamber  20 .  
         [0015]     Then, oxygen gas is supplied into the process chamber  20  at a predetermined flow rate (s 20 ). At this time, a low vacuum state is maintained in the process chamber  20 .  
         [0016]     Then, TEOS gas is supplied into the process chamber  20  along with the oxygen gas at a predetermined flow rate (s 30 ). Hence, the oxygen gas and the TEOS gas are mixed and flow over the wafer  22 . At this time, however, the oxygen gas and the TEOS gas cannot react uniformly because they are at room temperature. That is, the oxygen gas and the TEOS gas do not chemically react uniformly until a plasma is induced. Therefore, non-reacted TEOS gas agglomerates on the surface of the wafer  22   a.    
         [0017]     Then, RF power is applied to the plasma electrode  26  while the oxygen gas and the TEOS gas continue to flow into the process chamber  20  to induce a plasma reaction. As a result, a silicon oxide layer is formed on the wafer  22  (s 40 ). In this case, the high temperature causes the oxygen gas and the TEOS gas react uniformly.  
         [0018]     Once the silicon oxide layer attains a predetermined thickness, the supplying of the oxygen gas and the TEOS gas into the process chamber  20  is cut off, and the applying of RF power to the plasma electrode  26  is interrupted to extinguish the plasma. Oxygen gas and TEOS gas are then pumped out of the process chamber  20  (s 50 ).  
         [0019]     Then, purge gas is supplied into the chamber  20  while the process chamber  20  continues to be evacuated such that all of the oxygen gas and the TEOS gas remaining inside the process chamber  20  are removed from the process chamber (s 60 ). After a period of time, the supplying of the purge gas is then cut off and the purge gas remaining in the process chamber  20  is pumped out of the chamber  20  (s 70 ). The supplying of the purge gas into and the pumping of the purge gas from the chamber  20  can be performed periodically, i.e., can be repeated a number of times.  
         [0020]     However, the conventional CVD method described above has the following problem.  
         [0021]     The oxygen gas and the TEOS gas flowing over the wafer  22  do not react uniformly before the plasma is induced. Therefore, the non-reacted TEOS gas agglomerates on the wafer. As a result, the silicon oxide layer formed on the wafer  22  is non-uniform. The thickness of the silicon oxide layer can vary so much as to affect the processes which are to be subsequently carried out on the wafer. This failure of the deposition process lowers the overall production yield.  
       SUMMARY OF THE INVENTION  
       [0022]     Therefore, an object of the present invention is to provide chemical vapor deposition (CVD) equipment and a CVD method using the same by which contribute to increasing or optimizing the production yield.  
         [0023]     A more specific object of the present invention is to provide chemical vapor deposition (CVD) equipment and a CVD method using the same, in which the gases that constitute the source gas of the process are not allowed to flow over the substrate before the plasma reaction is induced.  
         [0024]     According to one aspect of the present invention, there is provided chemical vapor deposition (CVD) equipment including a source gas supply section, a process chamber in which a thin film is formed on a substrate using source gas from the source gas supply section, a supply line connecting the source gas supply section to the process chamber, an exhaust section by which air/gas is pumped from the process chamber, and a dump line connecting the supply line and the exhaust section and bypassing the process chamber.  
         [0025]     According to another aspect of the present invention, there is provided a CVD method including providing supply sources of first and second gases that together constitute the source gas of a CVD process, supplying only the first gas from the source thereof into the process chamber, subsequently supplying the second source gas and the first source gas from the sources thereof directly to an exhaust section by which air/gas is pumped from the chamber so that the gases bypass the process chamber, and then supplying the first source gas and the second source gas into the process chamber and simultaneously inducing a plasma reaction to thereby form a film on a substrate disposed in the chamber.  
         [0026]     According to still another aspect of the invention, there is provided a CVD method of forming a silicon oxide layer on a substrate, wherein the first and second gases are oxygen gas and TEOS gas, respectively. In this particular process, the oxygen gas is supplied into the process chamber at a flow rate of about 8000 sccm, the oxygen gas is supplied into the process chamber at a flow rate of about 350 sccm, air/gas is pumped out of the process chamber to maintain a vacuum pressure of about 2.5 Torr in the process chamber during the plasma reaction, and the plasma reaction is induced by exciting the source gas with an RF power of about 300 to 600 W. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments thereof made with reference to the attached drawings in which:  
         [0028]      FIG. 1  is a schematic diagram of conventional chemical vapor deposition (CVD) equipment;  
         [0029]      FIG. 2  is a flowchart illustrating a conventional CVD method;  
         [0030]      FIG. 3  is a schematic diagram of CVD equipment according to the present invention; and  
         [0031]      FIG. 4  is a flow chart illustrating a CVD method according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     The present invention will now be described in more detail with reference to the accompanying drawings.  
         [0033]     Referring to  FIG. 3 , the CVD equipment of the present invention includes a source gas supply section  100  providing a supply of source gas, a process chamber  200  in which a plasma reaction is induced using source gas from the source gas supply section  100  to form a thin film on a wafer  202 , a supply line  102  connecting the source gas supply section  100  to the process chamber  200 , an exhaust section  300  for pumping air/gas out of the process chamber  200 , and a dump line  500  connecting the supply line  102  to the exhaust section  300  so that source gas supplied from the source gas supply section  100  can bypass the process chamber  200 .  
         [0034]     More specifically, the dump line  500  is connected to the supply line  102  between the source gas supply section  100  and the process chamber  200 . A first valve  104  is disposed in the supply line  102  between the process chamber  200  and the location at which the dump line  500  is connected to the supply line  102 . A second valve  502  is disposed in the dump line  500 . The first valve  104  and the second valve  502  can be opened and closed independently of each other. Thus, source gas from the source gas supply section  100  is supplied to the process chamber  200  when the first valve  104  is opened and the second valve  502  is closed. On the contrary, the source gas flows through the dump line  500  to the exhaust section  300 , bypassing the process chamber  200 , when the first valve  104  is closed and the second valve  502  is opened.  
         [0035]     The source gas supply section  100  provides a plurality of gases which will generate a chemical reaction inside the process chamber  200  to form a thin film on a wafer  202 , and supplies the gases to the process chamber  200  at a predetermined flow rate. For example, the source gas may be a mixture of oxygen gas (first gas) and TEOS gas (second gas). Thus, the source gas supply section  100  includes an oxygen gas tank  105   a  and a TEOS gas tank  105   b , first and second flow control valves  106   a ,  106   b  controlling the rates at which the oxygen gas and the TEOS gas flow from the oxygen and TEOS gas tanks  105   a ,  105   b , respectively, and first and second shutoff valves  108   a ,  108   b  that can be opened or closed to selectively supply the oxygen gas and the TEOS gas to the supply line  102 . In this embodiment, the sections of the supply line  102  connected to the oxygen gas and TEOS gas tanks  105   a ,  105   b  merge into a single line from which the dump line  500  branches.  
         [0036]     Furthermore, the CVD equipment of the present invention includes a purge gas supply section  400  for supplying purge gas to the process chamber  200  through the supply line  102 . The purge gas supply section  400  includes a purge gas tank  105   c , a third flow control valve  106   c  controlling the rate at which the purge gas flows from the purge gas tank  105   c , and a third flow shutoff valve  108   c  that can be opened or closed to selectively supply the purge gas to the supply line  102 .  
         [0037]     The CVD equipment of the present invention may include a cleaning gas supply section (not shown) for supplying cleaning gas into the process chamber  200  through the supply line  102 . Any cleaning gas remaining in the supply line  102  after the cleaning process can be removed from the supply line  102  via the dump line  500 , i.e., without entering the process chamber  200 , prior to a subsequent deposition process.  
         [0038]     The CVD equipment also includes a shower head  206 , a chuck  204 , at least one plasma electrode  206 , and an external RF power source that applies an RF power to the at least one plasma electrode. The shower head  206  is disposed at the top of the process chamber  200  for uniformly spraying the source gas, such as oxygen gas and TEOS gas, over the wafer. The chuck  204  is disposed at the bottom of the process chamber  200  across from the shower head  206  for supporting the wafer  202  and fixing the wafer  202  in place during the deposition process. The chuck  204  also positions the wafer  202  at a distance of about 1.5 cm from the shower head  206 . The at least one plasma electrode  206  includes an electrode  206   b  disposed below the chuck  204  and/or an electrode  206   a  disposed over the shower head  202 . The at least one electrode  26  induces a high-temperature plasma reaction in the source gas when RF power is applied thereto.  
         [0039]     Preferably, the process chamber  200  is part of cluster type processing equipment in which a transfer chamber having a transfer robot is connected to the process chamber  200  for loading the wafer  202  into and unloading the wafer  202  from the process chamber  200 . In this type of equipment, the process chamber is maintained at a relatively high pressure during the thin film forming (deposition) process compared to the transfer chamber. Also, a heater fixed to the chuck  204  for heating the wafer  202  to a predetermined temperature, and a pressure gauge is provided for measuring the pressure (level of vacuum) inside the process chamber  200 . The pressure gauge may comprise a 1 Torr Baratron sensor (not shown) for measuring relatively low pressures and a 100 Torr Baratron sensor (not shown) for measuring relatively high pressures such that the pressure inside the process chamber  200  is measured in two steps. The pressure gauge may be directly installed inside the process chamber  200 , or may be installed in the exhaust line  302  whereby the pressure inside the process chamber  200  is determined according to the pressure of the air that is exhausted from the chamber  204 .  
         [0040]     The exhaust section  300  includes an exhaust line  302  extending from and communicating with the process chamber  200 , a vacuum pump system  304  connected to the exhaust line  302  for pumping air/gas out of the process chamber  200  through the exhaust line  302 , and a pressure control valve  306  disposed in the exhausting line  302  for controlling the amount of air/gas pumped from the process chamber  200  by the vacuum pump system  304  to maintain a vacuum, i.e., a certain level of negative pressure, inside the process chamber  200 . The vacuum pump system  304  may gradually increase the rate at which the air is pumped from the process chamber  200 . To this end, the vacuum pump system  304  includes a high vacuum pump  304   a  such as a turbo pump or a diffusion pump and a low vacuum pump  304   b  connected in series in the exhaust line  302  downstream of the pressure control valve  306 .  
         [0041]     In addition, a dummy exhaust line  302   a  diverges from the exhaust line  302  at a location between the high vacuum pump  304   a  and the process chamber  200  and rejoins the exhaust line  302  downstream of the high vacuum pump  304   a . A luffing valve  308   a  is disposed in the dummy exhaust line  302   a . A fore line valve  308  is disposed in the exhaust line  302  between the high vacuum pump  304   a  and the low vacuum pump  304   b , i.e., in the section of the exhaust line  302  from which the dummy exhaust line  302   a  extends. The luffing valve  308   a  and the fore line valve  308  can be opened and closed independently of each other like the first valve  104  and the second valve  102 . The exhaust section  300  further includes a scrubber (not shown) for purifying the air or the gas exhausted through the low vacuum pump  304   b  before the air/gas is vented to the atmosphere. The dump line  500  is connected to the exhaust line  302  at a fore end (upstream) of the low vacuum pump  304   b . Alternatively, the dump line can be connected to the dummy exhaust line between the luffing valve  308   a  and the low vacuum pump  304   b.    
         [0042]     A CVD method according to the present invention using the CVD equipment described above will now be described with additional reference to  FIG. 4 .  
         [0043]     First, a wafer  202  is loaded onto the chuck  204  in the process chamber  200  from a transfer chamber, and a door disposed between the process chamber  200  and the transfer chamber is closed. At this time, air is pumped from the process chamber  200  using the low vacuum pump  304   b  and the high vacuum pump  304   a  of the exhaust section  300  (s 100 ). For example, the air is pumped from the process chamber  200  using the low vacuum pump  304   b  with the luffing valve  308   a  open until a low level of vacuum of about 10 −3  Torr is produced in the chamber  200 . Then, the luffing valve  308   a  is closed, the fore line valve  308  is opened, and air is pumped from the process chamber  200  using the high vacuum pump  304   a  and the low vacuum pump  304   b  until a high level of vacuum of about 10 −6  Torr is produced in the chamber  200 .  
         [0044]     Then, oxygen gas is introduced into the process chamber  200  at a predetermined flow rate through the supply line  102  (s 200 ). For example, the oxygen gas is supplied into the process chamber  200  at a flow rate of about 8000 sccm for about 20 seconds. The flow rate of the oxygen gas is controlled by the first flow rate control valve  106   a  while the first valve  104  is open. At this time, a low level of vacuum is again produced in the process chamber  200  because of the oxygen gas in the process chamber  200 .  
         [0045]     Furthermore, the luffing valve  308   a  is closed, the fore line valve  308  is opened, and the low vacuum pump  304   b  and the high vacuum pump  304   a  pump air/gas from the process chamber  200  while the oxygen gas is supplied into the process chamber  200  until a vacuum pressure of about 2.5 Torr prevails in the process chamber  200 . Alternatively, only the low vacuum pump  304   b  may be used to pump the air from the process chamber  200  while the luffing valve  308   a  is closed and the fore line valve  308  is open. In any case, the vacuum pressure inside the process chamber  200  is regulated by the pressure control valve  306 .  
         [0046]     Next, the TEOS gas is supplied from the source gas supply section  100 , and the first valve  104  disposed in the supply line  102  is closed and the second valve  502  disposed in the dump line  502  is opened. Thus, the oxygen gas and the TEOS gas supplied from the source gas supply section  100  bypass the process chamber  200  by flowing to the exhaust section  300  through the dump line  500  for about 15 seconds (s 300 ). At this time, the flow rates of the oxygen gas and the TEOS gas are controlled to be the same as or similar to the rates at which the gases are supplied into the process chamber during the deposition process described below.  
         [0047]     For example, the oxygen gas is controlled to flow through the dump line  500  at a rate of about 8000 sccm, and the TEOS gas is controlled to flow through the dump line  500  at a rate of about 350 sccm. During this time, the vacuum pressure inside of the process chamber  200  is maintained at about 2.5 Torr. Furthermore, the wafer  202  is heated on the chuck  204  to a predetermined temperature.  
         [0048]     Then, the TEOS gas and the oxygen gas are supplied into the process chamber  200 . At the same time, RF power is applied to the plasma electrode  206  to induce a plasma reaction. As a result, a silicon oxide layer is formed on the wafer  202  (s 400 ). As mentioned above, the rates at which the TEOS gas and the oxygen gas are supplied into the process chamber  200  are the same as or similar to those as the rates at which the TEOS gas and the oxygen gas had been flowing through the dump line  500 .  
         [0049]     For example, the oxygen gas is supplied into the process chamber  200  at a flow rate of about 8000 sccm, and the TEOS gas is supplied into the process chamber  200  at a flow rate of about 350 sccm, both for about 9.4 seconds. Also, an RF power of about 300 to 600 W is applied to the source gas via the plasma electrode  206  to induce a plasma reaction. Still further, the temperature within the process chamber  200  is maintained at about 400° C., and the wafer  202  is also heated by the heater to have a temperature equal to or similar to the temperature in the process chamber  200 . The flow rate of gas pumped from the process chamber  200  by the vacuum pump system  304  is regulated by the pressure control valve  306  such that a vacuum pressure of about 2.5 Torr is maintained in the process chamber  200 .  
         [0050]     Then, the supplying of the TEOS gas and the oxygen gas supplied into the process chamber  200  is cut off, and the plasma reaction is terminated. At this time, TEOS gas and oxygen gas are pumped from the process chamber  200  by the exhaust pump system  304  for a predetermined period of time (s 500 ). For example, the gases are pumped out of the process chamber  200  for about 10 seconds at which time the process chamber has a vacuum pressure of about 0 Torr or less.  
         [0051]     Then, purge gas is supplied into the process chamber (s 600 ) through the supply line  102 , and any TEOS gas and oxygen gas remaining inside the process chamber  200  is diluted. As an example, nitrogen gas is supplied at a low flow rate for about 20 seconds so that polymer and silicon oxide, formed on the inner wall of the process chamber  200  as a result of the deposition process, will not peel off. Alternatively, the purge gas may be supplied into the process periodically at intervals of about 10 seconds. Moreover, at this time the vacuum pressure in the process chamber is regulated to be about 2.5 Torr.  
         [0052]     The air including the purge gas inside the process chamber  200  is exhausted by the vacuum pump system  304  until a predetermined vacuum pressure is produced inside the process chamber (s 700 ). These steps of supplying the purge gas into the process chamber (s 600 ) and pumping the air/gas out of the process chamber (s 700 ) can be performed periodically, i.e., can be repeated a number of times.  
         [0053]     Lastly, the door between the process chamber  200  and the transfer chamber is opened, and the robot disposed inside the transfer chamber transfers the wafer  202  from the chuck  204  to the transfer chamber, thereby completing the CVD process.  
         [0054]     As described above, according to the present invention, the oxygen gas and the TEOS gas are directed to the exhaust section through the dump line, thereby bypassing the process chamber, before the plasma reaction is induced. Specifically, the oxygen gas and the TEOS gas supplied from the source gas supply section  100  are directed to the exhaust section  300  through the dump line  500  so as to bypass the process chamber  200  as long as RF power is not applied to the plasma electrode  206 . Once the RF power is applied to the plasma electrode  206 , the oxygen gas and the TEOS gas are supplied into the process chamber  200  and are uniformly mixed, and the plasma reaction is thereby induced to form a uniform silicon oxide layer on the wafer including during the initial stage of the deposition process. That is, the TEOS gas is prevented from agglomerating on the surface of the wafer before the plasma reaction is induced. As a result, a uniform silicon oxide layer is formed by the deposition process, thereby increasing or optimizing a production yield.  
         [0055]     Finally, although the present invention has been described in connection with the preferred embodiments thereof, the scope of the invention is not so limited. Rather, various modifications and alternatives are sen to be within the true spirit and scope of the invention as defined by the appended claims.