Abstract:
A method of detecting a lift error of a piston used to elevate a wafer in a semiconductor manufacturing apparatus is disclosed. The method provides a time limit for a piston of a cylinder used to elevate a wafer to reach a specified position, a drive command is generated to drive the piston toward the specified position, a timer is started to measure a time period from the generation of the drive command, The piston detected whether it has reached the specified position, and an alarm and interlock signal are generated if the piston has not reached the specified position before the time period has exceeded the time limit.

Description:
BACKGROUND AND SUMMARY  
       [0001]     1. Technical Field  
         [0002]     The present invention generally relates to a method of manufacturing semiconductors. More particularly, the present invention relates to a method of reducing lift errors during the manufacturing of semiconductors.  
         [0003]     A claim of priority is made to Korean Patent Application 2004-43417, filed on Jun. 14, 2004, the contents of which are hereby incorporated by reference in their entirety.  
         [0004]     2. Description  
         [0005]     In general, a polymide process is performed to form a protective layer on a substrate. For example, a non-photosensitive photoresist material is used as the protective layer. To form the protective layer, a substrate is coated with the photoresist, and then the substrate is heated to a predetermined temperature in a baking unit to harden the coated photoresist.  
         [0006]     Generally a spinner is used to coat the photoresist. The spinner includes a photoresist supply line and a photoresist spraying nozzle to respectively supply and spray the photoresist onto the substrate. The spinner also includes a solvent supply line to clean and remove residual photoresist on the substrate. A solvent such as a thinner is used to perform a side rinse on an edge of the substrate and a back rinse on the backside of the substrate.  
         [0007]     The spinner further includes a baking unit having a high-speed rotational device. Prior to a fabrication process, the baking unit sets a baking time, baking temperature, temperature offset, a lower limit alarm, and an upper limit alarm as a hot-plate/cold-plate (HP/CP) recipe as shown in  FIG. 1 . As shown in  FIG. 2 , a low pressure addition hot (LPAH) recipe can be also set. In determining the HP/CP and LPAH recipes, when a RECIPE is selected on a menu screen of a controller, one or more sub-menus, such as for a coater, or bake unit appears. “Bake” sub-menu is selected, and then the HP/CP or LPAH recipe is selected to complete the set-up.  
         [0008]     However, one problem with a spinner apparatus, which is used to move substrates up and down during semiconductor manufacture, is that the substrates are often broken due to worn-out cylinder parts.  
         [0009]     Accordingly, it would be desirable to provide a method of detecting a lift error in a semiconductor manufacturing apparatus.  
       SUMMARY  
       [0010]     One aspect of the present invention provides a method of detecting a lift error of a piston used to elevate a wafer in a semiconductor manufacturing apparatus by inputting to a controller a time limit for a piston of a cylinder to reach a specific position, generating by the controller a drive command for a solenoid valve to drive the piston, and starting a timer, detecting by a sensor whether the piston has reached the specific position, and sending a detection signal to the controller when the piston reaches the specific position, and generating an alarm and interlock signal by the controller if a time required for the piston to reach the specific position exceeds the time limit.  
         [0011]     Another aspect of the present invention provides A method of detecting a lift error of a piston used to elevate a wafer in a semiconductor manufacturing apparatus by providing a time limit for a piston of a cylinder used to elevate a wafer to reach a specified position, generating a drive command to drive the piston toward the specified position, starting a timer to measure a time period from the generation of the drive command, detecting whether the piston has reached the specified position, and generating an alarm and interlock signal if the piston has not reached the specified position before the time period exceeds the time limit.  
         [0012]     And another aspect of the present invention provides a method of detecting a lift error of a piston used to elevate a wafer in a semiconductor manufacturing apparatus by providing a time limit for a piston of a cylinder used to elevate a wafer to reach a specified position, generating a drive command to drive the piston toward the specified position, starting a timer to measure a time period from the generation of the drive command, detecting whether the piston has reached the specified position, and in response thereto generating a detection signal, and generating an alarm and interlock signal if the detection signal is not detected. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The present invention will be better understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus do not limit the present invention, and wherein:  
         [0014]      FIG. 1  is a screen shot of a recipe setting for HP/CP bake unit;  
         [0015]      FIG. 2  is a screen shot of a recipe setting LPAH bake unit;  
         [0016]      FIG. 3  illustrates a baking unit according to an exemplary embodiment of the present invention;  
         [0017]      FIG. 4  is a flowchart to illustrate an input of up and down alarm times for a bake unit according to an exemplary embodiment of the present invention;  
         [0018]      FIG. 5  is a flowchart of a method of controlling lift errors according to another exemplary embodiment of the present invention;  
         [0019]      FIG. 6  illustrates screen shots used to enter a recipe before an application of an HP/CP method according to an exemplary embodiment of the present invention; and  
         [0020]      FIG. 7  illustrates screen shot of a recipe setting after applying an LPAH according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0021]     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS.  3  to  7 . It will be understood by those skilled in the art that the present invention can be embodied in numerous ways and is not limited to the following described embodiments. The following various embodiments are exemplary in nature.  
         [0022]      FIG. 3  illustrates a baking unit according to an exemplary embodiment of the present invention.  
         [0023]     Referring to  FIG. 3 , the baking unit includes a bake plate  10 , a lift pin holder  16 , a cylinder  18 , first and second sensors  20  and  22 , a controller  30 , first and second solenoid valves  24  and  26 , and an I/O (Input/Output) board  28 .  
         [0024]     Bake plate  10  has a pin hole  14  formed therethrough. A lift pin  12  moves within pin hole  14 . Lift pin  12  is connected to lift pin holder  16 . A wafer W is held in place under vacuum pressure on bake plate  10 .  
         [0025]     Cylinder  18  is connected to lift pin holder  16  to drive lift pin  12  by way of a piston disposed within cylinder  18  (not shown).  
         [0026]     First and second sensors  20  and  22  are individually installed in strategic positions on cylinder  18  to detect the position of the piston.  
         [0027]     Controller  30  outputs a solenoid valve control signal to move the piston during a baking process. Controller  30  receives a first or second detection signal from first or second sensors  20  and  22 , respectively, and in response thereto outputs a solenoid valve cut-off control signal. Controller  30  also sounds an alarm and simultaneously generates an interlock signal when the first or second detection signal is not received within a predetermined time after controller  30  generates the solenoid control signal.  
         [0028]     First and second solenoid valves  24  and  26  move the position of lift pin holder  16  in accordance with the signal received from controller  30 .  
         [0029]     I/O board  28  interfaces the first and second detection signals, transfers them to controller  30 , and respectively applies the solenoid valve cut-off control signal outputted from controller  30  to first and second solenoid valves  24  and  26 .  
         [0030]     Controller  30  is preferably a computer or any device capable of parameter input and management.  
         [0031]     To position lift pin holder  16  to a first position, e.g., an upper position, controller  30  outputs a first solenoid valve drive signal to second solenoid valve  26 . Second solenoid valve  26  opens and then supplies air to a lower portion of cylinder  18 , in response to which the piston elevates lift pin holder  16 . First sensor  20  detects an upper limit position of the piston when lift pin holder  16  is raised, and sends a detection signal to controller  30  through I/O board  28 . Controller  30  outputs the solenoid valve cut-off control signal to second solenoid valve  26  through I/O board  28 , and then second solenoid valve  26  closes and shuts off the air to cylinder  18 .  
         [0032]     To move lift pin holder  16  to a second position, e.g., a lower position, controller  30  outputs a second solenoid valve drive signal to first solenoid valve  24 . Then, first solenoid valve  24  opens and supplies air to an upper portion of cylinder  18 . When the air is supplied, the piston moves lift pin holder  16  down. Second sensor  22  detects a lower limit position of the piston and sends the detection signal to controller  30  via the I/O board  28 . Controller  30  outputs a solenoid valve cut-off control signal to first solenoid valve  24 , and in response thereto, first solenoid valve  24  closes and shuts off the air to cylinder  18 . The lowest position of the piston governs the lowest position of lift pin holder  16 , while the highest position of the piston governs the highest position of lift pin holder  16 .  
         [0033]     Referring to FIGS.  4  to  7 , operations of a method of controlling lift error in a semiconductor manufacturing apparatus will be disclosed.  
         [0034]     Referring first to  FIG. 4 , in determining lift pin holder upper and lower position alarm times for a baking unit, an operator selects a process parameter registration menu through a controller  30  (S 101 ). Controller  30  checks whether a bake recipe has been selected (S 102 ). If the bake recipe has been selected (S 102 ), controller  30  provides a screen menu similar to the ones depicted in FIGS.  6  or  7  to determine the lift pin holder up alarm time, and the lift pin holder down alarm time (S 103 ). Then, the operator inputs the lift pin holder up/down alarm times (S 104 ), for example, about 1.5 seconds each. Then controller  30  registers the pin holder up/down alarm times to a database (S 105 ).  
         [0035]     An operation of detecting and controlling a lift error generated during in a process after inputting, i.e., registering, the pin holder up/down alarm times will be described with reference to  FIG. 5 .  
         [0036]     A baking process commences after an operator inputs a baking process command through a controller  30 . Controller  30  begins the baking process (S 201 ). Then, controller  30  checks whether a drive command for a second solenoid valve  26  has been generated (S 202 ). If yes, controller  30  starts an internal timer (S 203 ). The second solenoid valve drive command is applied to second solenoid valve  26  through an I/O board  28 . Second solenoid valve  26  opens to supply air to a piston of a cylinder  18 . When the piston moves to a predetermined position, a first sensor  20  detects an upper limit position of the piston and sends a detection signal to controller  30  checks whether the detection signal has been received from first sensor  20  (S 204 ) and the process moves to step  205  regardless of the signal receipt from the sensor. In step  205 , controller  30  checks whether the timer has exceeded a pin holder up alarm determination time range. In other words, whether the time required to reach the first position has exceeded the allowed about 1.5 seconds. If the time has not been exceeded, the process returns to step  204 , but if time has been exceeded, the process moves to step  210 . In step  210 , controller  30  sounds an alarm to inform the operator that a lift error has occurred and also generates an interlock signal.  
         [0037]     If a second solenoid valve drive command is not generated in step  202 , the process moves to step  206  and controller  30  checks whether a drive command of a first solenoid valve has been generated, and if it has been generated, the process moves to step  207 . In step  207 , controller  30  starts an internal timer. The first solenoid valve drive command is applied to a first solenoid valve  24  through I/O board  28 . First solenoid valve  24  opens to supply air to the piston. When the piston moves to a predetermined position, a second sensor  22  detects a lower limit position of the piston and applies a detection signal to controller  30 . Controller  30  checks whether the detection signal was received from second sensor  22  (S 208 ), and the process moves to step  209  regardless of the signal receipt from the sensor. Controller checks whether the timer has exceeded a pin holder down alarm determination time range. In other words, controller  30  checks whether the time required to reach the second position has exceeded the allowed 1.5 seconds. If the time has not been exceeded, the process returns to step  208 , but if the time has been exceeded, the process moves to step  210 . In step  210 , controller  30  sounds an alarm to inform the operator that a lift error has occurred and also generates an interlock signal.  
         [0038]     As explained above, the pin holder up/down alarm times may be for example about 1.5 seconds. Once second solenoid valve  26  is driven, after about 1.2˜1.3 seconds a detection signal should be received by controller  30 . If controller  30  does not receive the detection signal by the allotted time, then controller  30  generates an alarm and interlock signal. Once first solenoid valve  24  is driven, after about 1.2˜1.3 seconds a detection signal should be received by controller  30 . If controller  30  does not receive the detection signal by the allotted time, then controller  30  generates an alarm and interlock signal.  
         [0039]     It will be apparent to those skilled in the art that modifications and variations can be made to the present invention without deviating from the scope of the present invention. Thus, it is intended that the present invention cover any such modifications and variations of the present invention.