JP2006114582A - Substrate accommodating apparatus and method for controlling impurity within the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate accommodating apparatus and impurity controlling method for controlling adhesion to semiconductor substrate of impurity such as water or the like in the atmosphere during the waiting or transfer of the semiconductor substrate in the semiconductor manufacturing process. <P>SOLUTION: With use of the substrate accommodating apparatus having adequately fed back gas flow rate and the impurity controlling method provided within the same substrate accommodating apparatus, adverse effect, for example, corrosion of wires and formation of naturally oxidized film or the like of impurity to semiconductor substrate can be prevented during the semiconductor manufacturing processes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate storage device for a semiconductor substrate in a semiconductor device manufacturing process and an impurity control method in the substrate storage device.

  In a semiconductor device manufacturing line, a semiconductor substrate transfer box is used to transfer a semiconductor substrate during the manufacturing process. When the semiconductor substrate in the semiconductor substrate transport box is adversely affected by moisture or oxygen in the atmosphere during the transfer or standby between processes, for example, a phenomenon such as corrosion of wiring or formation of a natural oxide film occurs. There is. In recent years, this phenomenon has become prominent with the miniaturization of design rules in semiconductor devices.

  For this reason, a transport box with a purge function using nitrogen gas having a function of purging the inside of the semiconductor substrate transport box with nitrogen or the like is used. In this case, nitrogen gas is allowed to flow through the transport box at a predetermined set flow rate. Moreover, the method of installing with a chemical filter and the method of measuring with a hygrometer are also used (for example, refer patent document 1).

However, impurities such as moisture adhering to the surface of the transport box or the semiconductor substrate being transported include the type of thin film formed on the semiconductor substrate, the type of process immediately before the semiconductor substrate has passed, the number of semiconductor substrates, the individual transport box It depends on the difference. Therefore, the reachable humidity in the respective transport boxes is different, and the required humidity is not reached, resulting in a decrease in the yield of the manufactured semiconductor device.
JP 2000-174109 A (page 8, FIG. 4)

  The present invention provides a substrate storage device and an impurity control method in the substrate storage device capable of controlling the adhesion of impurities such as moisture in the atmosphere to the semiconductor substrate during standby or transportation of the semiconductor substrate in a semiconductor manufacturing process. Objective.

  According to a first aspect of the present invention, as a substrate storage device, a sample storage box, a gas flow rate controller for controlling a flow rate of gas flowing in the sample storage box, and an instrument for measuring the amount of impurities in the gas in the sample storage box, And a control unit that receives data obtained by the measurement from the meter and feedback-controls the flow rate of the gas flow rate controller.

  The second aspect of the present invention is a measurement step of measuring the amount of impurities in the gas in the sample storage box in which the sample is stored and the gas is flown, as an impurity control method of the substrate storage device, A comparison step of comparing the measured impurity amount with a standard value that is a predetermined impurity amount, and as a result of the comparison, if the measured value is greater than the predetermined standard value, the gas flow rate is increased, and the measured value is An adjustment step for maintaining or reducing the gas flow rate when the gas flow rate is equal to or smaller than the standard value.

  The third aspect of the present invention is a measurement step of measuring the amount of impurities in the gas in the sample storage box in which the sample is stored and the gas is flowing as an impurity control method of the substrate storage device, A comparison step of comparing the measured impurity amount with a set value that is a predetermined impurity amount, and an adjustment step of reducing the gas flow rate when the measured value is equal to or less than the set value, To do.

  According to the present invention, by using a substrate storage device that appropriately feeds back a gas flow rate and an impurity control method in the substrate storage device, adverse effects on the semiconductor substrate due to impurities during the semiconductor manufacturing process, such as corrosion of the wiring, natural oxidation, etc. Formation of a film can be prevented. Therefore, a high yield semiconductor device can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  A first embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram showing an outline of a substrate storage device. 2A is a schematic view of a sample storage box body and a sample storage box lid in the substrate storage device, and FIG. 2B is a schematic view of a carrier cassette for installing a semiconductor substrate to be inserted into the sample storage box body. It is.

  FIG. 3 is a flowchart showing the procedure of the impurity control method in this embodiment. Control moisture with moisture as an impurity. Furthermore, FIG. 4 is a graph showing the time dependence of the humidity in the substrate storage device obtained by the humidity control method shown in FIG.

  First, the substrate storage apparatus shown in FIG. 1 will be described. The substrate storage device 10 includes a sample storage box body 11a in which a semiconductor substrate is set as a sample and a sample storage box lid 11b for taking in and out the semiconductor substrate, and a hygrometer for measuring the humidity in the sample storage box 11. 12. Control unit for controlling the entire substrate storage device 10 including the flow rate control of the gas flow rate controller 13 based on the humidity measurement result by the gas flow rate controller 13 and the hygrometer 12 that sends the gas into the sample storage box 11 14 and a pipe 15 used for gas input / output. A valve 15a is installed in the middle of the pipe 15 so that the sample storage box 11 can be easily removed.

  A schematic diagram of the sample storage box main body 11a and the sample storage box lid 11b is shown in FIG. The sample storage box 11 is made of, for example, polycarbonate. The bottom surface of the sample storage box 11 is a sample storage box lid 11b lid, and the semiconductor substrate is taken in and out from there. The semiconductor substrate is installed in the sample storage box main body 11a in a state of being placed in, for example, the carrier cassette 15 shown in FIG. That is, the semiconductor substrate (not shown) is inserted into the substrate holding groove 16 a in the carrier cassette 16 so as to be horizontal with the bottom surface of the sample storage box 11.

  The carrier cassette 16 may be made integrally with the sample storage box body 11a. In this case, the sample storage box lid 11b is formed not as the bottom surface of the sample storage box 11, but as one of the side surfaces of the sample storage box 11, for example.

  For example, nitrogen gas is introduced from the pipe 15 through the gas inlet 11c of the sample storage box body 11a in a state where the sample storage box 11 is sealed by the sample storage box body 11a and the sample storage box lid 11b. And is discharged from the gas discharge port 11d. At this time, the gas flow rate is controlled by the flow rate controller 13.

  On the other hand, the humidity of the gas discharged by purging the sample storage box 11 is measured by the hygrometer 12. The measured data is sent to the control unit 14. A microcontroller unit (not shown) in the control unit 14 compares predetermined data stored in the memory in the circuit with the obtained data and determines the flow rate to be controlled. Further, a flow rate instruction signal to be set is sent from the control unit 14 to the flow rate controller 13.

  Next, the procedure and effect of the humidity control method in the present embodiment will be described with reference to FIGS. The semiconductor substrate in this example is in the stage of moving to the next process after Al is formed as the wiring in the wiring process. Therefore, a substrate storage device is used to prevent oxidative corrosion of the Al wiring.

  FIG. 3 is a flowchart showing the procedure of the humidity control method in the present embodiment. The procedure will be described with reference to the schematic diagram of the substrate storage device of FIG. First, a semiconductor substrate is placed in the substrate storage device 10 and, as a gas, for example, nitrogen gas dried to a high purity of about several ppm is flowed (S10). FIG. 4 is a graph showing the time dependency of the humidity in the substrate storage device in the present embodiment. For example, the sample A and the sample B are put in different substrate storage devices.

  Sample A is a sample showing a standard transition with respect to time dependency of humidity. For example, first, a flow rate of 50 l / min is passed through the substrate storage device 10. Subsequently, after extruding the initially existing atmosphere (for example, after 3 minutes), the flow rate is reduced to, for example, 10 l / min (S11). Further, the humidity is measured with the hygrometer 12 after 10 minutes (S12). For example, as shown in the graph of FIG. 4, the humidity is 25% RH.

  This data is then sent to the control unit 14. The control unit 14 stores predetermined data relating to the time dependency of humidity in a memory circuit in a microcontroller unit (not shown). In accordance with an instruction from the CPU in the microcontroller unit, the measured value is compared with the stored data (S13).

  If the humidity 25% RH, which is 10-minute data after starting, is almost equal to or lower than the standard humidity transition value (standard value), for example, 10 l / min is maintained without changing the flow rate. (S14).

  On the other hand, the sample B has a humidity of about 34% RH after 10 minutes. In this case, since the measured value becomes larger than the standard value, it is necessary to further reduce the humidity more rapidly. Therefore, the humidity transition is read from the predetermined data, and the necessary flow rate is set. For example, in this case, it is set to 20 l / min (S15). By such setting, a humidity decrease curve as shown in the sample B of FIG. 4 can be obtained.

  In the conventional example, since the flow rate is not controlled and, for example, 10 l / min is maintained, it takes time to reduce the humidity as in the sample B (conventional). For this reason, the corrosion of the Al wiring has progressed, and the yield of the manufactured semiconductor device may deteriorate. On the other hand, the standard value shown in the present embodiment is a function of time. A number of standard values are prepared in advance, and the time transition is predicted by collating data actually measured. It is possible to adjust the flow rate so that a desired humidity is obtained at a necessary time from the prediction.

  Further, when the humidity is measured at a predetermined time and reaches a set value of, for example, 5% RH for preventing the oxidative corrosion of the Al wiring (S16), for example, the flow rate is reduced to 2 l / min to control this impurity. This step is finished.

  In this case, the semiconductor substrate is held in the substrate storage apparatus until the next process is moved, and when moving to the next process, the pipe is disconnected from the valve 15a, for example, an apparatus in which the next process is performed in the transport system. Carry it to the vicinity.

  By using the substrate storage device and its humidity control method shown in this embodiment, appropriate flow rate control can be obtained, and the progress of corrosion of Al wiring in the semiconductor manufacturing process can be prevented. Further, as a humidity control method, the controllability becomes very high by comparing with an actual measurement value using a standard value. Therefore, a high yield semiconductor device can be obtained.

  In the first embodiment, in the wiring process, after Al is formed as the wiring, the process proceeds to the next process. Therefore, a substrate storage device was used to prevent oxidative corrosion of the Al wiring.

  On the other hand, the semiconductor substrate in this embodiment is in a stage before the element isolation process is completed and before the gate insulating film forming process, and a substrate storage device is used to control the formation of the natural oxide film. The substrate storage box in the present embodiment is basically the same as the first embodiment in configuration and the description thereof is omitted here.

  FIG. 5 is a flowchart showing the procedure of the oxygen amount control method in this embodiment. In this embodiment, only the set value of humidity is used, but a method is used in which a plurality of set values are determined in advance and the flow rate is lowered step by step when the measured value of humidity reaches the set value. For example, in this embodiment, as the plurality of setting values, the first setting value uses a humidity of 5% RH, and the second setting value uses a humidity of 1% RH.

  First, a semiconductor substrate is placed in a substrate storage device, and as a gas, for example, nitrogen gas dried to a high purity of about several ppm is flowed (S20). First, a first flow rate of 50 l / min is passed through the substrate storage device as the gas flow rate. Subsequently, after extruding the initially existing atmosphere (for example, after 3 minutes), for example, after 10 minutes, the humidity is measured with a hygrometer (S21).

  This data is then sent to the control unit. In the control unit, the obtained data is compared with the first set value of 5% RH (S22), and when the measured value is smaller than the first set value, the flow rate is automatically reduced and the second set value is set. The flow rate is 10 l / min (S23). On the other hand, when the measured value is equal to or larger than the first set value, the flow rate is left at the first flow rate of 50 l / min. In this case, the humidity is measured again after a predetermined time.

  Next, the humidity is measured with a hygrometer after the set time has elapsed in a state where the gas is supplied at a second flow rate of 10 l / min (S21). Subsequently, this data is sent to the control unit, and the obtained data is compared with 2% RH which is the second set value in the control unit (S22). If the measured value is smaller than the second set value, the flow rate is automatically reduced to a third flow rate of 2 l / min (S23). On the other hand, if the measured value is equal to or greater than the second set value, the flow rate is kept at the second flow rate of 10 l / min. In this case, the humidity is measured again after a predetermined time.

  The above steps are repeated and, for example, the impurity control step is terminated after a predetermined time has elapsed since the third flow rate was set to 2 l / min.

  In this case, the semiconductor substrate is held in the substrate storage apparatus until the next process is moved, and when moving to the next process, the pipe is disconnected from the valve 15a, for example, an apparatus in which the next process is performed in the transport system. Carry it to the vicinity.

  In the conventional example, since the specific flow rate is maintained without controlling the flow rate, it may take a lot of time to reduce the moisture. Therefore, a natural oxide film is formed on the semiconductor surface and manufactured. The yield of semiconductor devices sometimes deteriorated.

  By using the substrate storage device and the impurity control method in the substrate storage device shown in this embodiment, the formation of a natural oxide film on the surface of the semiconductor substrate in the semiconductor manufacturing process can be suppressed. Therefore, a high yield semiconductor device can be obtained.

  A third embodiment will be described with reference to FIG. The substrate storage box and its impurity control method in this embodiment are basically the same as those in the first embodiment. The difference is that, in the first embodiment, Al is formed as the wiring of the wiring process in the first embodiment, and then the process moves to the next process. Therefore, a substrate storage device was used to prevent oxidative corrosion of the Al wiring. On the other hand, the semiconductor substrate in this embodiment is in a stage before the source and drain formation process is completed and before the inter-wiring insulating layer formation process is performed, and a substrate storage device is used to suppress the generation of boron precipitates.

  Since the substrate storage apparatus used in this embodiment is the same as the substrate storage apparatus 10 in the first embodiment, description thereof is omitted.

  FIG. 6 is a flowchart showing the procedure of the humidity control method in this embodiment. The procedure will be described with reference to the schematic diagram of the substrate storage device of FIG. First, a semiconductor substrate is placed in a substrate storage device, and as a gas, for example, nitrogen gas dried to a high purity of about several ppm is flowed (S30).

  First, 50 l / min is passed through the substrate storage device 10 as the flow rate. Subsequently, after extruding the initially existing atmosphere (for example, after 3 minutes), the flow rate is reduced to, for example, 5 l / min (S31). Further, after 10 minutes, moisture is measured with the hygrometer 12 (S32).

  This data is then sent to the control unit 14. The control unit 14 stores predetermined data relating to the time dependency of humidity in a memory circuit in a microcontroller unit (not shown). In accordance with an instruction from the CPU in the microcontroller unit, the measured value is compared with the stored data (S33).

  When the water content, which is data 10 minutes after the start, is almost equal to or lower than the standard humidity transition value (standard value), for example, 5 l / min is maintained without changing the flow rate ( S34).

  On the other hand, when the measured value is larger than the standard value as the humidity after 10 minutes, it is necessary to further rapidly decrease the water concentration. Therefore, the moisture concentration transition is read from predetermined data, and a necessary flow rate is set. For example, in this case, it is set to 10 l / min (S35). With such settings, a moisture concentration decrease curve can be obtained.

  In the conventional example, since the flow rate is not controlled and, for example, 5 l / min is maintained, it takes much time to reduce the moisture. For this reason, boron precipitates are formed on the semiconductor surface, and the yield of the manufactured semiconductor device may deteriorate.

  Furthermore, when the amount of water is measured at a predetermined time and reaches a value set as the amount of water that prevents the formation of boron precipitates, for example, a set value of 15% RH, for example, the flow rate is reduced to 2 l / min. The impurity control step is completed.

  In this case, the semiconductor substrate is held in the substrate storage device until the next step is moved, and when moving to the next step, the pipe is removed from the valve, for example, near the device where the next step is performed in the transfer system. You can carry it up to.

  By using the substrate storage device and the impurity control method in the substrate storage device shown in this embodiment, the formation of boron precipitates on the surface of the semiconductor substrate in the semiconductor manufacturing process can be suppressed. Therefore, a high yield semiconductor device can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  In the embodiment, moisture is measured as an impurity. However, the oxygen concentration may be measured using an oxygen concentration meter. For example, it is applied to control the formation of a natural oxide film before the gate insulating film forming step. It is possible. Further, impurities used in the semiconductor manufacturing process, such as fluorine, chlorine, ammonia, etc. may be measured.

  Further, the type of gas flowing through the substrate storage box is not limited to nitrogen gas, and may be an inert gas such as argon gas or helium gas. Of course, the flow rate may be an appropriate value according to the process.

The schematic diagram which shows the outline of the board | substrate storage apparatus in 1st Example by this invention. The schematic diagram (a) of the sample storage box main body and sample storage box lid of the substrate storage apparatus in the first embodiment according to the present invention, and the schematic diagram (b) of the carrier cassette holding the semiconductor substrate in the sample storage box main body. The flowchart which shows the general | schematic procedure of the impurity control method in 1st Example by this invention. The graph which shows the time dependence of the humidity in the board | substrate storage apparatus in 1st Example by this invention. The flowchart which shows the general | schematic procedure of the impurity control method in 2nd Example by this invention. The flowchart which shows the general | schematic procedure of the impurity control method in the 3rd Example by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate storage apparatus 11 Sample storage box 11a Sample storage box main body 11b Sample storage box lid 11c Gas inlet 11d Gas outlet 12 Hygrometer 13 Flow controller 14 Control unit 15 Pipe 15a Valve 18 Carrier cassette 18a Substrate holding groove

Claims (5)

A sample storage box;
A gas flow rate controller for controlling the gas flow rate flowing in the sample storage box;
An instrument for measuring the amount of impurities in the gas in the sample storage box;
And a control unit that receives data obtained by the measurement from the meter and feedback-controls the flow rate of the gas flow rate controller. A measurement step of measuring the amount of impurities in the gas in the sample storage box in which the sample is stored and the gas is flowing;
A comparison step of comparing the measured impurity amount with a standard value that is a predetermined impurity amount;
As a result of the comparison, if the measured value is larger than the predetermined standard value, the gas flow rate is increased, and if the measured value is equal to or smaller than the standard value, the gas flow rate is maintained or decreased. And an impurity control method for a substrate storage device.   3. The impurity control method for a substrate storage apparatus according to claim 2, wherein the standard value depends on a time after flowing the gas into the sample storage box and decreases as the time elapses. A measurement step of measuring the amount of impurities in the gas in the sample storage box in which the sample is stored and the gas is flowing;
A comparison step of comparing the measured impurity amount with a set value that is a predetermined impurity amount;
An impurity control method for a substrate storage apparatus, comprising: an adjusting step for decreasing the gas flow rate when the measured value is equal to or smaller than the set value.   The impurity control method for a substrate storage device according to claim 4, wherein the impurity has a plurality of measurement values.

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