Abstract:
This invention provides a method for chamber conditioning with deposition mode. The method includes performing organic gas introduced constantly into a chamber, wherein said organic gas comprises halogen. Adhesive polymers are formed from said organic gas and particles in the chamber, and deposited onto the wall of the chamber to form heavy polymers subsequently. It is necessary to make a similar chamber condition for manufacturing every batch of wafer. In other words, the development of a non-ignored pollution problem, which is increasing with batches of the manufacturing of wafers will not occur. By using said method of deposition mode, it is speedily and easy to decrease the amount of particles in the chamber for the requirement for wafer manufacturing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The proposed invention is related to a chamber conditioning method and more particularly to a method for applying “deposition mode” to down the amount of particles in that chamber to an acceptable range.  
           [0003]    2. Description of the Prior Art  
           [0004]    The requirements of semiconductor manufacturing must be performed under an extremely clean environment. Products of the reactions in said manufacturing are not only deposited onto wafers as desired, but also attached to the wall of the manufacturing chamber. During manufacturing, the pollutant, such as particles, will be deposited and accumulated gradually onto the wall and components of the chamber. Over time, if the particles fail to be cleaned from the chamber, a degraded, unreliable processes and defective substrates may result. Lack of a regular procedure for cleaning causes the migration of the particle residues onto substrates and pollution of said manufacturing process. Particularly, when the residues are peeling, the yield kill rate can be higher than 10%. Thus, it is necessarily to look for an efficient and economical chamber conditioning method to lower the amount of particles in the chamber so as to enhance the property and quality of the products from the chamber. Traditionally, there are two methods of chamber conditioning, i.e. in-situ cleaning (also known as dry cleaning) and wet cleaning.  
           [0005]    In opposition to the dry cleaning procedure, in which the processing chamber remains closed, the wet cleaning procedure is performed by breaking the processing chamber&#39;s vacuum seal and manually wiping down the chamber&#39;s interior surfaces. Such a wet cleaning operation affects a processing system&#39;s throughput in a worse way than a dry cleaning operation does. When a wet clean is performed, opening the processing chamber and physically wiping the chamber&#39;s interior surfaces results in more down-time (about 14 to 16 hours), compared to the dry clean which only takes minutes, because the process must subsequently be re-stabilized. A wet clean procedure is normally performed to remove residues that are not entirely removed by the in-situ cleaning process, and thus slowly accumulate over time. After longer periods of time, typically about 9000 RF-minutes (150 RF-hour), a wet clean is required to be performed.  
           [0006]    The above-mentioned process of chamber conditioning of the clean mode at least comprises the following, shown as the flow chart as FIG. 1:  
           [0007]    Firstly, at least one gas, such as SF 6 , Cl 2 , O 2  and the like, is introduced into a chamber, which contains particles. Particles in the chamber will react with said gas and become a volatile gas, shown as the forming volatile gas step  10 . Then the gas in the chamber is pumped away with vacuum system, shown as the pumping step  12 , and process gas is purged into the chamber to displace the gas in the chamber, shown as the gas displacement step  14 . Finally, as shown in the test step  16 , a test wafer is used to confirm whether the influence of the particle residues in the chamber on process of wafer manufacturing is qualified as desired or not. If the answer is “no”, it is necessary to return to the forming volatile gas step  10 , and repeat the conditioning steps.  
           [0008]    Wherein said chamber conditioning method with dry cleaning procedure, particles in the chamber are taken away by reacting with the introduced gas to form volatile gas, and pumping away with a vacuum system. There are some particles probably still remaining in the chamber after the pumping step. It is because the introduced gas can not completely react with particles in the chamber.  
           [0009]    Wherein said chamber conditioning method with a dry cleaning procedure, the above-mentioned method usually takes a long time because of the complexity of the chamber, and thus it will affect the throughput of the manufacturing. Furthermore the particle residues, which are still attached to wall of the chamber after chamber conditioning, may escape from the wall, become a pollutant source in the subsequent manufacture, and affect the stability of the manufacturing.  
           [0010]    Wherein said chamber conditioning method with dry cleaning procedure, it is necessary to perform a judging step using test wafers to confirm the influence of the particle residues on the manufacture. Said step is not only inconvenient, but also very uneconomical for wafer manufacturing.  
           [0011]    In said traditional chamber conditioning method with clean mode, clean gas is introduced into a chamber  20 , shown as FIG. 2A. Under power from an upper electrode  24  and a lower electrode  26 , particles in said chamber  20  react with the introduced gas and form volatile products  28 , as shown in FIG. 2B. Sequentially, volatile gas  28  and inactive clean gas are pumped out from chamber  20  shown in FIG. 2C. Refer to FIG. 2D, a test wafer  32  is sent into the chamber  20  and used to confirm the influence of particle residues  30  on the manufacturing. For example, in Shallow Trench Isolation etching process, the chamber conditioning process is completed, when depth of the trenches on test wafers reach to the desired level of stability. On the other hand, the chamber conditioning process has to be repeated if the depth of the trench can not reach to the desired stable level.  
           [0012]    Downtime of performing the clean mode process means the damage of throughput of wafer. Thus, it is very important to lower downtime of chamber conditioning to rise the throughput of wafer. For this object, in other words, it is necessary to broaden the meantime between clean process, wherein said clean process is wet clean procedure which consumes much time. So it is important to find out some kind of method to improve the chamber conditioning method. Especially, it is necessary to provide a method for lowering the influence of particles in the manufacture and rising the yield and throughput of wafer.  
         SUMMARY OF THE INVENTION  
         [0013]    In accordance with the present invention, a method is provided for chamber conditioning that is useful for stabilizing of the wafer manufacture.  
           [0014]    It is another object of this invention to simplify the process of chamber conditioning and to make the control of the process of chamber conditioning more easily.  
           [0015]    It is a further object of this invention to increase stability of the subsequent process of manufacture.  
           [0016]    It is still another object of this invention that it is not necessary to use a test wafer in chamber conditioning process.  
           [0017]    It is yet another object of this invention that it is not necessary to pass through the steps of pumping and purging and the introducing gases that will not cause influence in subsequent manufacturing process.  
           [0018]    In accordance with the above-mentioned objects, the presented invention provides a new chamber conditioning method, in which introduced organic gas comprising halide is utilized to form adhesive polymer with particles. The polymer will deposit on wall of the chamber and form heavy polymers. Preferably, said organic gas will not influence manufacturing semiconductor. Thus it will lower the amount of particles in the chamber speedily, and make the controlling of the process of chamber conditioning more easily.  
           [0019]    On the other hand, the polymers formed from particles and the introduced gas can fasten particles on the wall of the chamber; thus there is no particle escaping from the wall and becoming a source of influence in manufacturing. Preferably, the adhesive heavy polymers, which are formed from the deposition of the adhesive polymer, can stabilize manufacture by trapping particles produced in the manufacturing.  
           [0020]    In one preferred embodiment, the presented invention provides a chamber conditioning process with deposition mode. The process comprises the following steps. Firstly, at least one organic gas is introduced into a chamber. Secondly, adhesive polymers are formed from the introduced gas and particles in the chamber. Then the polymers are deposited to wall of the chamber and formed heavy polymers. Finally, the chamber conditioning is completed when the heavy polymer is saturated. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0022]    [0022]FIG. 1 is an essential flow diagram showing the steps of traditional of chamber conditioning process with clean mode.  
         [0023]    [0023]FIG. 2A to FIG. 2C are a series of qualitative illustrations of traditional chamber conditioning process with clean mode.  
         [0024]    [0024]FIG. 3 is an essential flow diagram showing the steps of this presented invention of chamber conditioning process with deposition mode.  
         [0025]    [0025]FIG. 4A to FIG. 4C are a series of qualitative illustrations of this presented invention of chamber conditioning process with deposition mode.  
         [0026]    [0026]FIG. 5 is an illustration showing the application of the presented invention in a chamber of Shallow Trench Isolation Etching process. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    Some sample embodiments of the invention will now be described in greater detail. Nevertheless, it should be recognized that the present invention can be practiced in a wide range of other embodiments besides those explicitly described, and the scope of the present invention is expressly not limited except as specified in the accompanying claims.  
         [0028]    It is important to control the amount of particles in a chamber in a suitable range during wafer manufacturing. The point of the presented invention is providing a chamber conditioning process with deposition mode. Wherein above-mentioned process, organic gas is constantly introduced into a chamber and thus adhesive polymers are formed from particles in the chamber and the introduced gas. Said polymers are deposited onto the wall of the chamber and formed heavy polymers until said heavy polymers are saturated. The above-mentioned process can speedily lower the amount of particles in the chamber to a desired level and make the controlling of chamber conditioning process more efficient and easy.  
         [0029]    This presented invention provides a chamber conditioning process with deposition mode. The above-mentioned process can transfer particles in the chamber into polymers and fix the polymers onto walls of the chamber while wafer manufacturing is performed. Thus the process does not have to expend minutes for chamber conditioning before every wafer manufacturing.  
         [0030]    All of the chamber conditioning process can be shown as a flow diagram as FIG. 3. Firstly, at least one organic gas comprising halogen is introduced into a chamber, wherein the organic gas substantially comprises elements of carbon, hydrogen, oxygen, and halogen. In this embodiment, the preferred gas is CH 2 CF 2 , or CHF 3 . The introduced gas forms adhesive polymers with particles in the chamber, shown as step  34  for forming polymer. The polymers are deposited onto the wall of the chamber, and heavy polymers are formed, shown as step  36  for depositing polymer. Refer to step  38  for judging the clean level, when the deposition of the polymer is saturated, i.e. when the etching rate of the wafer in the chamber is stable, it means chamber conditioning of the chamber is finished, shown as step  40  for finishing chamber conditioning.  
         [0031]    One preferred embodiment of this presented invention is a chamber conditioning process with deposition mode. A preferred embodiment according to this invention is set forth below and referred to FIG. 4.  
         [0032]    After used to produce several batches of wafers, there are particles  44  that will affect the yield of next manufacturing existing in a chamber  42 , as shown in FIG. 4A.  
         [0033]    At least one organic gas containing halogen is constantly introduced into the chamber  42 , wherein the organic gas substantially comprises elements of carbon, hydrogen, oxygen, and halogen. In this embodiment, the preferred gas is CH 2 CF 2 , or CHF 3 . Under power from an upper electrode  46  and a lower electrode  48 , particles  44  in the chamber  42  are reacted with the introduced gas and formed adhesive polymers  50 , shown as FIG. 4B. Through above-mentioned step, the organic gas is helpful not only for fixing particles, but also for trapping the suspended particles and fixing them onto wall of the chamber  42 . Thus the step can decrease the influence of particle for efficiency of wafer manufacturing.  
         [0034]    Referred to FIG. 4C, the polymers  50  adhered onto wall of chamber  42  are deposited and formed heavy polymers  52 . When the deposition of the heavy polymers  52  are saturated, chamber conditioning process is finished, and the next manufacture can be begun. The deposited heavy polymer on the wall of the chamber will be cleaned by wet clean when the device is in periodical clean.  
         [0035]    Because of the organic gas constantly introduced into the chamber, the polymers formed from the particles are deposited onto wall until the deposition of the polymers is saturated, and thus the process can decrease the amount of suspended particles and keep the stability of the later manufacturing.  
         [0036]    One of the differences between the deposition mode and clean mode is necessary of using a test wafer. In the deposition mode, the chamber conditioning is finished when the deposition of the polymer on the wall is saturated. It is not necessary to use a test wafer to ensure the influence of the particle residues in the chamber. The chamber can be an etching chamber, which can be applied to Sallow Trench Isolation etching.  
         [0037]    About the comparison between the above-mentioned two chamber conditioning methods, the chamber conditioning with clean mode and the chamber conditioning with deposition mode, it is shown in Table 1 behind this article. In regards to compare the cost time of chamber conditioning, in deposition mode, the particles become polymers and attach onto the wall. So, it does not have to perform the steps of pumping out the particles, as clean mode, before the next manufacture. In other words, deposition mode can save time in pumping and switching the valve of the chamber during this step, so it can finish chamber conditioning in a shorter time.  
         [0038]    Moreover, in chamber conditioning method with deposition mode, if sad organic gas is constantly introduced into the chamber, there are polymers formed and deposited onto the wall of the chamber to form heavy polymers until the deposition of the heavy polymers is saturated. Thus the above-mentioned method makes the operation of chamber conditioning easier and controllable. Because the particles (polymers) are deposited onto the wall directly, the efficiency of chamber conditioning is not limited to the complexity of the chamber&#39;s inner structure.  
         [0039]    The adhesive polymers formed from particles and the introduced gas can fix the particles onto the wall of the chamber, so it will not allow that particles to escape from wall and affect the stability of wafer manufacturing. Moreover, the adhesive heavy polymers deposited on wall of the chamber may trap some of particles produced during manufacturing, and help to keep the stability of the subsequent manufacturing.  
         [0040]    In order to describe the presented invention concretely, another preferred embodiment shown in FIG. 5 is a stable method of Shallow Trench Isolation etching (STI etching), wherein the method comprising the following steps:  
         [0041]    The process gas is introduced from a gas inlet  56 , through a shower head  60 , into a Shallow Trench Isolation etching chamber  54 . The process gas comprises etching gas and organic gas, which comprises elements of carbon, hydrogen, oxygen, and halogen. In this preferred embodiment, the more preferable gas is CH 2 F 2 , or CHF 3 .  
         [0042]    After respectively electrifying a coil  58  and a substrate  64 , the introduced gas is formed plasma in chamber  54 , and begun to work. The introduced etching gas will etch wafer  62 , and the introduced organic gas will form adhesive polymers with particles in chamber  54 . The two kinds of reaction can be carried out at the same time, and they will not influence each other.  
         [0043]    The adhesive polymers are deposited onto wall of the chamber  54 , and formed heavy polymers. The saturation of deposition of the heavy polymers is shown as the stability of the etching rate in the manufacturing. When the etching rate tends to be stable, most of the particles are transferred to polymers and deposited onto wall of chamber  54 .  
         [0044]    In the above-mentioned embodiment, the chamber has to be wet clean every 3000 wafers to certify the quality of wafers from the chamber.  
         [0045]    In the preferred embodiment, it is not required to stop the manufacturing and carry out the chamber conditioning process after each ending of wafer manufacturing. It is only necessary to control the mix ratio of process gas and the organic gas in the introduced gas to perform manufacturing and particle trapping at the same time.  
         [0046]    Although specific embodiments have been illustrated and described, it will be obvious to those skilled in the art that various modifications may be made without departing from what is intended to be limited solely by the appended claims.  
                         TABLE 1                           Comparison between deposition mode and clean mode            Clean mode   Deposition mode               Performing after each ending of   passable performing during the       manufacture   manufacture       Introducing etching gas   introducing mix gas       Pumping out particles (volatile gas)   depositing particles (polymer)           onto wall of the chamber       Limiting the efficiency to the   Not limiting the efficiency to the       structure of chamber   structure of chamber       Controlling not easy   Controlling easy.       Test wafer necessary   Test wafer not necessary