Abstract:
An etching system and method. In the method, layers are etched on a plurality of substrates using a single amount of etchant to form a predetermined pattern on each of the layers, wherein an etching period varies according to an accumulated process number of substrates. The system includes an etching equipment including an etching processor for etching layers on a plurality of substrates using a single amount of etchant to form a predetermined pattern on each of the layers, and a loader for temporarily holding cassettes in which the substrates are stored; and a controller for controlling operations of the etching equipment. The etching equipment changes an etching period according to an accumulated process number of the substrates.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    (a) Field of the Invention  
           [0002]    The present invention relates to an etching system and a method for fabricating microelectronics devices such as a semiconductor device or a liquid crystal display (LCD). More particularly, the present invention relates to an etching system and a method that varies an etching period according to the accumulated number of microelectronics devices being etched.  
           [0003]    (b) Description of the Related Art  
           [0004]    Microelectronics devices such as a semiconductor device or an LCD are formed by integrating a plurality of minute patterns. The patterns are formed by a variety of fabrication steps, one of which is an etching process. There are two main types of etching in microelectronics fabrication: wet etching and dry etching. A wet etching method uses liquid etchants while a dry etching method uses plasma.  
           [0005]    The conventional wet etching process for an LCD will be described hereinafter.  
           [0006]    In the LCD manufacturing process, it is necessary to form metal patterns of gate lines and data lines. These metal patterns are etched using an etchant containing nitric acid (HNO 3 ). A large number of LCDs repeatedly use the same etchant of a certain amount in order to reduce the manufacturing costs. However, the more LCDs are etched (in other words, an “accumulated process number” increases) in the same etchant of a certain amount, the less nitric acid component remains in the etchant, resulting in a lowered etching rate. Thus, if LCDs are etched for the same period of time without considering the accumulated process number of substrates that the etchant fabricated, a critical dimension (CD) of the metal patterns increases as the accumulated process number increases.  
           [0007]    [0007]FIG. 1 shows a graph illustrating a relation between the accumulated process number and the CD in the conventional process for manufacturing an LCD.  
           [0008]    In the conventional process for manufacturing an LCD, LCDs are etched for a predetermined amount of time (at an overetching rate), without considering the accumulated process number. As shown in FIG. 1, in the conventional process for manufacturing LCDs, the CD increase has an almost linear relationship with the increase in the accumulated process number. Accordingly, the conventional LCD manufacturing process requires changing the etchant when the accumulated process number reaches a certain value (CDo), e.g., 300 devices, where the CD also reaches its tolerance point.  
           [0009]    As a result, the conventional LCD manufacturing method wastes etchants a lot, thereby increasing the overall manufacturing costs.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention has been made in an effort to solve the above problems.  
           [0011]    It is an object of the present invention to provide an etching system and a method for fabricating microelectronic devices that varies the etching period according to the accumulated process number of microelectronic devices that the etching system has handled.  
           [0012]    To achieve the above object, the present invention provides an etching system and a method. The method according to the present invention etches the layers on a plurality of substrates using the same etchant of a certain volume to form a pattern on each of the layers, but changes the etching period according to the accumulated process number of substrates.  
           [0013]    According to a feature of the present invention, the LCDs are etched at first for a period of T1 until the accumulated process number reaches N substrates, and are etched for a period of T2 when the accumulated process number goes beyond N substrates.  
           [0014]    According to another feature of the present invention, the etching period varies for each different accumulated process number.  
           [0015]    According to yet another feature of the present invention, substrates are etched using a functional value of a process time with regard to the accumulated process number.  
           [0016]    According to still yet another feature of the present invention, optimal etching periods for different accumulated process numbers are obtained through experimental tests, and the optimal etching periods are stored in a memory and used to perform etching.  
           [0017]    The etching system includes an etching equipment having an etching processor for etching layers on a plurality of substrates using an etchant to form a predetermined pattern on each of the layers, and a loader for temporarily holding cassettes that store the substrates; and a controller for controlling operations of the etching equipment. The etching equipment changes the etching period according to an accumulated process number of the substrates.  
           [0018]    According to a feature of the present invention, the controller transmits to the etching equipment a first operation recipe including a first etching period T1 when the accumulated process number is between 1 and N substrates, and a second operation recipe including a second etching period of T2 when the accumulated process number is N+1 or more substrates; and wherein the etching equipment performs etching according to the first operation recipe and the second operation recipe.  
           [0019]    According to another feature of the present invention, the controller receives data corresponding to the accumulated process number from the etching equipment when a cassette is loaded on the loader, and transmits the first operation recipe or the second operation recipe to the etching equipment according to the received data.  
           [0020]    According to yet another feature of the present invention, the etching equipment etches substrates using the etching period that varies depending on each different accumulated process number .  
           [0021]    According to still yet another feature of the present invention, the etching equipment etches substrates using a functional value of a process time with regard to the accumulated process number, the functional value being stored in a memory, and the etching equipment uses the functional value to perform etching.  
           [0022]    According to still yet another feature of the present invention, optimal etching periods for different accumulated process numbers are obtained through tests, and the optimal etching periods are stored in a memory and used for etching by the etching equipment. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention:  
         [0024]    [0024]FIG. 1 is a graph illustrating the relationship between an accumulated process number and a CD in the conventional LCD manufacturing process;  
         [0025]    [0025]FIG. 2 is a block diagram of an etching system according to a preferred embodiment of the present invention;  
         [0026]    [0026]FIG. 3 is a drawing illustrating communications between an etching equipment and a controller shown in FIG. 2;  
         [0027]    [0027]FIG. 4 is a graph illustrating the relationship between an accumulated process number, an etching period and a CD according to a first preferred embodiment of the present invention; and  
         [0028]    [0028]FIG. 5 is a graph illustrating the relationship between an accumulated process number, an etching period and a CD according to a second preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
         [0030]    [0030]FIG. 2 shows a block diagram of an etching system according to a preferred embodiment of the present invention. The etching system comprises an etching equipment  100  and a controller  200 . The etching equipment  100  includes a loader  120 , an etching processor  140 , and a transport robot  160 .  
         [0031]    The controller  200  of the etching equipment  100  controls operations of the etching equipment  100 . In more detail, when a cassette is loaded on the loader  120  of the etching equipment  100  by an automatic transporter (not shown), the loader  120  transmits a signal to inform the controller  200  of the reception of the cassette. The controller  200  then transmits an operation recipe to the etching equipment  100 . The operation recipe includes various process conditions such as an etching period, an etchant amount, a time when to replace the etchant, etc. Glass substrates in the cassette are processed according to the operation recipe.  
         [0032]    The transport robot  160  of the etching equipment  100  removes from the cassette the glass substrates that require processing in the etching processor  140  and transports the glass substrates to the etching processor  140 . The etching processor  140  etches the glass substrates received from the transport robot  160  according to the operation recipe transmitted from the controller  200 .  
         [0033]    In the present invention, the etching period varies according to an accumulated process number of the glass substrates. The etching period varies by using one of two methods: a method according to a first preferred embodiment of the present invention controls the etching period by the controller  200 , and a method according to a second preferred embodiment of the present invention controls the etching period in the etching equipment  100 .  
         [0034]    Controlling the etching period by the controller  200  will first be described.  
         [0035]    When controlling the etching period according to the first preferred embodiment of the present invention, the controller  200  keeps two recipes, each having a different etching period (overetching rate). In more detail, after changing the etchant, an operation recipe of a first etching period T1 (30% overetching rate) is used until the accumulated number of substrates processed by the etchant reaches 400, while an operation recipe of a second etching period T2 (60% overetching rate) is used when the accumulated process number falls between 401 and 1000 glass substrates. The second etching period T2 is longer than the first etching period T1. In this embodiment, T1 is 43 seconds and T2 is 53 seconds for the aluminum etching process. In this way, for substrates are used two operation recipes having etching periods (overetching rates) that varies depending on whether the accumulated process number is less or greater than a predetermined number (400 in this case).  
         [0036]    When the cassette is loaded on the loader  120 , the controller  200  receives from the etching equipment  100  an accumulated process number corresponding to the number of glass substrates processed in the etching equipment. Using this information, the controller  200  controls the etching equipment  100  such that the substrates are etched using the operation recipe having an overetching rate of 30% when an accumulated process number is 400 or less, or using the operation recipe having an overetching rate of 60% when an accumulated process number is 401 or more.  
         [0037]    [0037]FIG. 3 shows a drawing illustrating communications between the etching equipment  100  and the controller  200  of FIG. 2. First, the etching equipment  100  sends a cassette load command to the controller in step S 11 . The controller  200  then searches an internal database to locate an ID of a cassette holding the correct glass substrates that has to be processed, and outputs to the automatic transporter a command to load the correct cassette to the etching equipment  100  in step S 12 . As a result, the automatic transporter removes the correct cassette from a stocker (not shown) and places the cassette on the loader  120 , and then a message reporting the completion of the cassette loading is transmitted to the controller  200  by the etching equipment  100  in step S 13 .  
         [0038]    The controller  200 , then, sends a response signal to the etching equipment  100  in step S 14 , then sends a request to the etching equipment  100  for an accumulated process number of glass substrates in step S 15 . The etching equipment  100  then calculates the accumulated process number and sends the same to the controller  200  in step S 16 . Subsequently, the controller  200  sends an operation recipe having an etching period (overetching rate) corresponding to the accumulated process number, and also transmits a start command to the etching equipment  100  in step S 17 . As a result, the etching controller  100  sends a response signal to the controller  200  in step S 18 , after which the etching equipment  100  begins to operate and reports to the controller  200  the start of operation in step S 19 .  
         [0039]    In the etching system using the method of controlling the etching period according to the first preferred embodiment of the present invention, at least two operation recipes each having different etching periods are programmed in the controller  200 . In this way, after receiving the accumulated process number from the etching equipment  100  at the time of loading, the operation recipe having the etching period suitable for the accumulated process number is transmitted to the etching equipment  100 . The glass substrates are processed in the etching equipment  100  according to the operation recipe received from the controller  200 .  
         [0040]    In the etching system using the method of controlling the etching period according to the first preferred embodiment of the present invention, since the accumulated process number is altered if the etchant is changed when the glass substrates are loaded onto the loader  120 , the system automatically stops processing glass substrates. After changing the etchant, the system restarts the processing of the glass substrates using the new operation recipe selected according to the new accumulated process number.  
         [0041]    [0041]FIG. 4 is a graph illustrating the relationship between the accumulated process number, the etching period and CD according to the first preferred embodiment of the present invention. As shown in the drawing, after the etchant is changed, substrates are etched at an overetching rate (etching period) of 30% when the accumulated process number is between 0 and 400 substrates. In this case, the CD increases at a regular rate as the accumulated process number increases. On the other hand, if the accumulated process number surpasses 400, substrates are etched at an overetching rate (etching period) of 60%. The CD decreases when the accumulated process number is at 401, then starts to increase again as the accumulated process number increases.  
         [0042]    As a result, more LCDs can be produced using the same amount of etchant within a predetermined CD range in the present invention than in the prior art.  
         [0043]    Table 1 below compares CD values of substrates manufactured according to the prior art method with those manufactured by the method according to the first preferred embodiment of the present invention.  
                                                               TABLE 1                                   Accumulated       ACI (μm)           process number   Overetching rate   (target 4.1 μm)                                    Prior Art   1-1000 substrates   30%   4.312       First preferred   1-400 substrates   30%   4.131       embodiment   401-1000   60%   4.080           substrates                average   4.105                      
 
         [0044]    As is shown in Table 1 above, in the prior art method, substrates are etched at an overetching rate of 30% regardless of the accumulated process number of substrates, and an ACI (after cleaning inspection) value of 4.312 μm is obtained. The ACI of 4.312 μm is 0.212 μm greater than a target value of 4.1 μm.  
         [0045]    On the other hand, in the method according to the first preferred embodiment of the present invention, at an accumulated process number of between 1 and 400 substrates, substrates are etched at an overetching rate of 30%, while the overetching rate is increased to 60% at an accumulated process number of between 401 and 1000 substrates. Respective ACI values are 4.131 μm and 4.080 μm, with an average ACI value of 4.105 μm. Therefore, it is evident that the target value of 4.1 μm is realized in the present invention.  
         [0046]    The method according to the second preferred embodiment of the present invention that controls the etching period in the etching equipment 100 will be described hereinafter.  
         [0047]    According to the second preferred embodiment of the present invention, the etching equipment 100 is provided with an offset program to automatically adjust the etching period (overetching rate) within a single operation recipe according to the accumulated process number. That is, rather than changing the operation recipe (i.e., etching period) for a group of substrates in a non-continuous fashion as in the first preferred embodiment, the etching period changes within a single operation recipe to correspond to changes in the accumulated process number. Accordingly, since substrates can be etched using a single operation recipe, an identical operation recipe is used to process all the glass substrates supplied to the loader  120 .  
         [0048]    It is possible to use two different variations of the method of the second preferred embodiment of the present invention. In the first variation, substrates are etched using a functional value of the process time with regard to the accumulated process number. In the second variation, optimal etching periods for different accumulated process numbers are obtained from testing, and these values are stored in a memory. The stored etching periods are used by the etching equipment  100  to etch the glass substrates.  
         [0049]    [0049]FIG. 5 shows a graph illustrating the relationship between the accumulated process number, etching period and CD according to the second preferred embodiment of the present invention. Using the method according to the second preferred embodiment of the present invention, after the etchant is changed, etching periods are increased according to increases in the accumulated process number such that the CD is maintained at a constant level. Accordingly, more LCDs can be produced within a predetermined CD range in the present invention than in the prior art.  
         [0050]    In the etching system and method of the present invention described above, since the etching period varies according to the accumulated process number, the number of substrates that can be fabricated with a certain amount of etchant is increased.  
         [0051]    Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims.  
         [0052]    For example, in the first preferred embodiment of the present invention, although two operation recipes having different etching periods were described, those skilled in the art will readily recognize that three or more operation recipes can be applied to this embodiment. Also, the present invention can be applied to semiconductor devices, etc. and is in no way limited to using with LCDs.