Abstract:
An optical sensor circuit comprises an optical sensor adapted to sense a position of a component in a semiconductor manufacturing apparatus according to the presence or absence of a flag and output a signal indicative of the position. A position sensing driver receives the signal via a path selected by a plurality of switches and then drives an output signal in response to the signal. The path selected by the plurality of switches causes the optical sensor circuit to act as either a close-type optical sensor circuit or an open-type optical sensor circuit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to an optical sensor circuit for a semiconductor manufacturing device. More particularly, the invention relates to an optical sensor circuit that combines the functions of both “open-type” and “close-type” optical sensor circuits into a single optical sensor circuit.  
         [0003]     A claim of priority is made to Korean Patent Application No. 10-2004-0110967 filed Dec. 23, 2004, the disclosure of which is hereby incorporated by reference in its entirety.  
         [0004]     2. Discussion of Related Art  
         [0005]     Optical sensors are commonly used to detect the positions and/or orientations of various components within a piece of semiconductor manufacturing equipment. For instance, optical sensors may be used to detect whether a printed circuit board is properly positioned or whether parts of the equipment such as doors, valves, and so forth, are properly positioned (e.g., open, closed, tilted, rotated, etc.). The optical sensors are generally coupled to or associated with actuators such as pivot motors, door motors, and air springs, which are used to adjust the positions and/or orientations of the various components.  
         [0006]     An ion-implantation apparatus is one type of equipment that uses optical sensors. In an ion implantation apparatus, components such as isolation valves, faradays, and load lock chambers, are monitored by optical sensors. For example, the optical sensors may detect whether the load lock chambers or the or the isolation valves are properly opened or closed. In addition, the optical sensors may be used to determine whether an ion source or a substrate is in a proper position for ion-implantation to take place.  
         [0007]     In a “close-type” optical sensor circuit, when an obstruction, or “flag”, prevents a light emitting diode (LED) from transmitting light to a light receiving transistor, the optical sensor circuit outputs a signal with a logic state “low” (i.e., a “low signal”). In contrast, in an “open-type” optical sensor circuit, when a flag prevents the LED from transmitting light to the light receiving transistor, the optical sensor circuit outputs a signal with a logic state “high” (i.e., a “high signal”).  
         [0008]      FIG. 1  is a circuit diagram of a conventional “close-type” optical sensor circuit and  FIG. 2  is a circuit diagram of a conventional “open-type” optical sensor circuit.  
         [0009]     Referring to  FIG. 1 , the conventional close-type optical sensor circuit comprises an optical sensor  10 , a position sensing driver  12 , and a LED “LED 1 ”. The close-type optical sensor circuit further comprises a first resistor R 1  and a second resistor R 2  connected to optical sensor  10 .  
         [0010]     Optical sensor  10  comprises a LED D 1  and a light receiving transistor TR 1  that is turned on in response to light emitted from LED D 1 . A flag “FLAG” is inserted or input between LED D 1  and light receiving transistor TR 1  to prevent the light emitted from LED D 1  from turning on light receiving transistor TR 1 .  
         [0011]     Position sensing driver  12  comprises a transistor  12  having a base connected to an emitter of light receiving transistor TR 1 , a collector connected to an output of LED “LED 1 ”, and an emitter connected to an output of the close-type optical sensor circuit.  
         [0012]     The operation of the close-type optical sensor circuit is as follows. Where flag “FLAG” is not interposed between LED D 1  and light receiving transistor T 1 , the emitter of light receiving transistor T 1  assumes logic state “high”, causing transistor Q 1  to turn on. Accordingly, current flows through LED “LED 1 ”, causing it to turn on, and as a result, the emitter of transistor Q 1  assumes logic state “high”. In contrast, where flag “FLAG” is interposed between LED D 1  and light receiving transistor T 1 , the emitter of light receiving transistor T 1  assumes logic state “low”, causing transistor Q 1  to turn off. Accordingly, no current flows through LED “LED 1 ”, and as a result, the emitter of transistor Q 1  assumes logic state “low”.  
         [0013]     The operation of the close-type optical sensor circuit is illustrated by Table 1 below.  
                               TABLE 1                       FLAG POSITION   TR1   Q1   LED1   Q1 EMITTER                   FLAG IN   OFF   OFF   OFF   LOW       FLAG OUT   ON   ON   ON   HIGH                  
 
         [0014]     Referring now to  FIG. 2 , the open-type optical sensor circuit comprises an optical sensor  20 , a position sensing driver  22 , a LED “LED 2 ”, and first and second resistors R 1  and R 12 . Optical sensor  20  comprises a LED “D 2 ” and a light receiving transistor TR 2  that is turned on in response to light emitted by LED D 2 . A flag “FLAG” is inserted or input between LED D 2  and light receiving transistor TR 2  to prevent the light emitted from LED D 2  from turning on light receiving transistor TR 2 . Position sensing driver  22  comprises a transistor Q 2  having a base connected to a collector of light receiving transistor TR 2 , a collector connected to an output of LED “LED 2 ”, and an emitter connected to an output of the open-type optical sensor.  
         [0015]     The operation of the open-type optical sensor circuit is as follows. Where flag “FLAG” is not interposed between LED D 2  and light receiving transistor T 2 , the collector of light receiving transistor T 2  assumes logic state “low”, causing transistor Q 2  to turn off. Accordingly, no current flows through LED “LED 2 ”, and as a result, the emitter of transistor Q 2  assumes logic state “low”. In contrast, where flag “FLAG” is interposed between LED D 2  and light receiving transistor T 2 , the collector of light receiving transistor T 2  assumes logic state “high”, causing transistor Q 1  to turn on. Accordingly, current flows through LED “LED 2 ”, thus turning it on, and as a result, the emitter of transistor Q 2  assumes logic state “high”.  
         [0016]     The operation of the close-type optical sensor circuit is illustrated by Table 2 below.  
                               TABLE 2                       FLAG POSITION   TR2   Q2   LED2   Q2 EMITTER                   FLAG IN   OFF   ON   ON   HIGH       FLAG OUT   ON   OFF   OFF   LOW                  
 
         [0017]     In the description above, the close-type optical sensor circuit outputs a high signal when no flag is input to optical sensor  10 , and the open-type optical sensor circuit outputs a low signal when no flag is input to optical sensor  20 . Conversely, where a flag is input to optical sensor  10 , the close-type optical sensor circuit outputs a low signal and where a flag is input to optical sensor  20 , the open-type optical sensor circuit outputs a high signal.  
         [0018]     The output of the closed or open type optical sensor generally provides an indication of the state of some component in a semiconductor manufacturing device. For example, the output may represent whether a door in the device is open or closed. The optical sensor typically detects the state of the component by the presence or absence of the flag.  
         [0019]     The optical sensor circuits described above are commonly employed in semiconductor manufacturing equipment. For example, in a semiconductor manufacturing apparatus comprising a processing chamber and a plurality of load lock chambers connected to the process chamber, optical sensor circuits may be used to determine whether the load-lock chambers are properly closed or whether an air bearing in the processing chamber is properly oriented.  
         [0020]     Where a close-type or open-type optical sensor circuit is used in the load lock chambers of a semiconductor manufacturing apparatus, malfunctions in one optical sensor circuit can be addressed without interrupting semiconductor manufacturing processes in the processing chamber. This can be accomplished, for example, by removing the malfunctioning optical sensor circuit from its respective load lock chamber and using a different load lock chamber to perform process steps. However, where a close-type or open-type optical sensor circuit is used in the processing chamber, malfunctions in the optical sensor circuit cannot be addressed without interrupting semiconductor manufacturing processes performed therein.  
       SUMMARY OF THE INVENTION  
       [0021]     According to one embodiment of the invention, an optical sensor circuit adapted for use in a semiconductor manufacturing apparatus is provided. The optical sensor circuit comprises an optical sensor adapted to sense a position of a component in the semiconductor manufacturing apparatus according to the presence or absence of a flag and output a signal indicative of the position, and a position sensing driver receiving the signal via a path selected by a plurality of switches and driving an output signal in response to the signal.  
         [0022]     According to another embodiment of the invention, another optical sensor circuit adapted for use in a semiconductor manufacturing apparatus is provided. The optical sensor circuit comprises an optical sensor adapted to sense a position of a component in the semiconductor manufacturing apparatus according to the presence or absence of a flag, a pull-up resistor connected between a power supply and the optical sensor, and a pull-down resistor connected between the optical sensor and ground. The optical sensor circuit further comprises a first switch connected between the power supply and the optical sensor, a second switch connected between the optical sensor and ground, a position sensing driver comprising a transistor having a base, an emitter, and a collector, a third switch connected between the optical sensor and the base of the transistor, and a fourth switch connected between the base of the transistor and the optical sensor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     The invention is described below in relation to several embodiments illustrated in the accompanying drawings. Throughout the drawings like reference numbers indicate like exemplary elements, components, or steps. In the drawings:  
         [0024]      FIG. 1  is a diagram of a conventional close-type optical sensor circuit;  
         [0025]      FIG. 2  is a diagram of a conventional open-type optical sensor circuit; and,  
         [0026]      FIG. 3  is a diagram of an optical sensor circuit combining the functions of a close-type and open-type optical sensor circuit according to one embodiment of the present invention. 
     
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0027]     Exemplary embodiments of the invention are described below with reference to the corresponding drawings. These embodiments are presented as teaching examples. The actual scope of the invention is defined by the claims that follow.  
         [0028]      FIG. 3  is a diagram of an optical sensor circuit combining the functions of a close-type and open-type optical sensor circuit according to one embodiment of the present invention.  
         [0029]     Referring to  FIG. 3 , the optical sensor circuit comprises an optical sensor  30 , a position sensing driver  32 , a LED “LED 11 ”, first and second pull-up resistors R 1  and R 2 , a pull down resistor R 3 , and first through fourth switches SW 1  through SW 4 . The optical sensor circuit further comprises a connecter J 1  connecting the optical sensor circuit to a power supply Vcc (1), an output terminal (2), and ground (3).  
         [0030]     Optical sensor  30  comprises a LED D 11  connected between first pull-up resistor R 1  and ground. Optical sensor  30  further comprises a light receiving transistor TR 11  having an emitter and a collector and turning on in response to light emitted by LED D 11 . A flag “FLAG” is inserted or input between LED D 11  and light receiving transistor TR 11  to prevent the light emitted from LED D 11  from turning on light receiving transistor TR 11 .  
         [0031]     Position sensing driver  32  comprises a negative-positive-negative (NPN) bipolar transistor Q 11  connected between an output of LED LED 11  and the output terminal. Transistor Q 11  has a base connected to switch SW 3 , a collector connected to the output of LED LED 11 , and an emitter connected to the output terminal.  
         [0032]     In  FIG. 3 , first pull-up resistor R 1  is connected between the power supply and LED D 11 , second pull-up resistor R 2  is connected between the power supply and the collector of light receiving transistor TR 11 , and pull-down resistor R 3  is connected between the emitter of light receiving transistor TR 11  and ground.  
         [0033]     First switch SW 1  is connected between the power supply and the collector of light receiving transistor TR 11 , second switch SW 2  is connected between the emitter of light receiving transistor TR 11  and ground, third switch SW 3  is connected between the collector of light receiving transistor TR 11  and the base of transistor Q 11 , and fourth switch SW 4  is connected between the emitter of light receiving transistor TR 11  and the base of transistor Q 11 .  
         [0034]     By selectively closing (or turning on) first through fourth switches SW 1  through SW 4 , the optical sensor circuit of  FIG. 3  can perform the functions of the close-type optical sensor circuit of  FIG. 1  or the functions of the open-type optical sensor circuit of  FIG. 2 . As illustrated by the following table 3, the optical sensor circuit of  FIG. 3  acts as an open-type optical sensor circuit when second and third switches SW 2  and SW 3  are on and first and fourth switches SW 1  and SW 4  are off. The optical sensor circuit of  FIG. 3  acts as a close-type optical sensor circuit when first and fourth switches SW 1  and SW 4  are turned on and second and third switches SW 2  and SW 3  are turned off.  
                                       TABLE 3                                   OPTICAL SENSOR                           CIRCUIT TYPE   SW1   SW2   SW3   SW4                           CLOSE-TYPE   ON   OFF   OFF   ON           OPEN-TYPE   OFF   ON   ON   OFF                      
 
         [0035]     Where the optical sensor circuit of  FIG. 3  functions as the close-type optical sensor circuit, the output terminal receives a high signal whenever flag “FLAG” is not interposed between LED D 11  and light receiving transistor TR 11 , and the output terminal receives a low signal whenever flag “FLAG” is interposed between LED D 11  and light receiving transistor TR 11 . On the other hand, where the optical sensor circuit of  FIG. 3  functions as the open-type optical sensor circuit, the output terminal receives a low signal whenever flag “FLAG” is not interposed between LED D 11  and light receiving transistor TR 11 , and the output terminal receives a high signal whenever flag “FLAG” is interposed between LED D 11  and light receiving transistor TR 11 .  
         [0036]     Where the optical sensor circuit acts as the closed-type optical sensor circuit and flag “FLAG” is not interposed between LED D 11  and light receiving transistor TR 11 , light receiving transistor TR 11  is turned on, and fourth switch SW 4  connects the emitter of light receiving transistor TR 11  to the base of transistor Q 11  to turn on transistor Q 11 . Current then flows through LED 11  and transistor Q 11  to output a high signal on the output terminal.  
         [0037]     Where the optical sensor circuit acts as the closed-type optical sensor circuit and flag “FLAG” is interposed between LED D 11  and light receiving transistor TR 11 , light receiving transistor TR 11  is turned off, and fourth switch SW 4  connects the base of transistor Q 11  to ground through pull-down resistor R 3 . Therefore, no current flows through LED 11  and transistor Q 11 , and therefore a low signal is output to the output terminal.  
         [0038]     Where the optical sensor circuit acts as the open-type optical sensor circuit and flag “FLAG” is not interposed between LED D 11  and light receiving transistor TR 11 , light receiving transistor TR 11  is turned on, and third switch SW 3  connects the base of transistor Q 11  to a low voltage to turn transistor Q 11  off. Accordingly, no current flows through LED 11  and therefore transistor Q 11  outputs a low signal on the output terminal.  
         [0039]     Where the optical sensor circuit acts as the open-type optical sensor circuit and flag “FLAG” is interposed between LED D 11  and light receiving transistor TR 11 , light receiving transistor TR 11  is turned off, and third switch SW 3  connects the base of transistor Q 11  to the power supply through second pull-up resistor R 2 . Accordingly, transistor Q 11  is turned on and current flows through LED 11 . As a result, a high signal is sent to the output terminal.  
         [0040]     Because the optical sensor circuit shown in  FIG. 3  is capable of acting as both a close-type optical sensor circuit and an open-type optical sensor circuit, semiconductor manufacturing processes do not necessarily have to be terminated when a part of the optical sensor circuit malfunctions. Accordingly, the productivity of semiconductor manufacturing processes are greatly enhanced in the face of optical sensor circuit malfunctions.  
         [0041]     Although the optical sensor circuit shown in  FIG. 3  contains bi-polar NPN transistors, transistors with other polarities (i.e., PNP transistors) could also be used instead, and the polarities of signals could be modified accordingly to produce output signals in accordance with the desired functionality of the optical sensor circuit.  
         [0042]     Various types of switches could be used to form the circuit shown in  FIG. 3 . For example, dual in-line package (DIP) switches, transistors, and the like could be used. In general, the switches are turned on and off by a control circuit (not shown) so that either switches SW 1  and SW 4  are on at the same time while switches SW 2  and SW 3  are off in order to perform like a close-type optical sensor circuit or switches SW 2  and SW 3  are on at the same time while switches SW 1  and SW 4  are off in order to perform like an open-type optical sensor circuit.  
         [0043]     The foregoing preferred embodiments are teaching examples. Those of ordinary skill in the art will understand that various changes in form and details may be made to the exemplary embodiments without departing from the scope of the present invention which is defined by the following claims.