JP4906558B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

  The present invention relates to a process gas supply technique, and more particularly to a process gas supply technique for supplying a process gas to a plasma processing apparatus.

  Conventionally, when desired microfabrication is performed on an object to be processed such as a silicon wafer or an LCD substrate in a manufacturing process of a semiconductor chip or the like, the reactive gas introduced into the processing chamber is turned into plasma by electromagnetic waves, and this plasmaized reaction is performed. 2. Description of the Related Art Plasma etching apparatuses that perform an etching process on the object to be processed using a reactive gas are widely used.

  In a plasma processing apparatus, in order to perform uniform plasma processing on a target object, it is necessary to distribute a plurality of process gases to be introduced to a uniform concentration over the entire processing surface of a wafer that is a target object.

  In recent years, the outer diameter of silicon wafers used for semiconductor manufacturing has increased from 200 mm to 300 mm. Accordingly, it has become difficult to perform uniform plasma processing over a wide area on the silicon wafer. For this reason, after mixing a plurality of process gases, they are introduced into the processing chamber via a diffusion filter provided at the introduction port, or gas supply lines having independent flow rate control devices are provided, and the respective supply lines are provided. The process gas is supplied to the center and outer peripheral edge of the silicon wafer.

  As such a technique, Patent Document 1 discloses a method for uniformly distributing a gas on the surface of a wafer that is an object to be processed.

Patent Document 2 discloses a method for monitoring plasma emission in a vacuum processing chamber and monitoring and controlling control values such as gas flow rate, high frequency power, pressure, temperature, and magnetic field intensity based on fluctuations in plasma emission. Has been.
JP 2006-41088 A JP 2000-21856 A

  By the way, in the plasma etching processing apparatus having a plurality of gas supply lines as described above, when the shape of the process gas inlet in each supply line is different from each other, or when the gas pipe volume (pipe length) is different from each other. Even if the gases are simultaneously supplied from one side of each supply line, the time required for the process gas to reach the vacuum processing chamber is different.

  If the arrival time of the process gas introduced into the vacuum processing chamber is different, when the process gas is switched, the plasma formed on the wafer, which is the object to be processed, is not in the plasma due to the desired process gas. In such a case, a desired etching result cannot be obtained.

  The present invention has been made in view of such problems, and provides a process gas supply technique capable of performing plasma processing under desired process gas conditions by adjusting the timing at which the process gas reaches the vacuum processing chamber. To do.

  In order to solve the above problems, the present invention employs the following means.

A vacuum processing chamber with a reduced pressure inside,
A gas supply source for supplying a process gas to the vacuum processing chamber ;
A plasma generating apparatus for generating plasma by supplying high-frequency energy to the process gas supplied to the vacuum processing chamber ;
A gas supply line for supplying the process gas supplied from the gas supply source to the vacuum processing chamber via a gas flow rate control device, a gas circuit breaker, and a gas supply line;
A plasma emission detector for detecting plasma onset light of the vacuum processing chamber,
A control controller for performing flow rate control of the process gas, timing control of supply and stop of the process gas, and analysis of the plasma emission,
The control controller sets the process gas as the time required for the plasma emission to reach a predetermined intensity as the time required for the process gas to reach the vacuum processing chamber after the supply of the process gas is started. Measured in advance as the time required for the plasma emission to reach a predetermined intensity, the time required for the process gas in the vacuum processing chamber to decrease after the supply of gas is stopped, and only the pre-measured arrival time The supply of the process gas is started early with the gas flow rate of the processing condition, and the supply of the process gas is quickly stopped for a pre-measured decrease time.

  Since the present invention has the above-described configuration, it is possible to provide a process gas supply technique capable of performing plasma processing under desired process gas conditions by adjusting the timing at which the process gas reaches the vacuum processing chamber.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a process gas supply apparatus according to a first embodiment of the present invention. As shown in FIG. 1, a process gas supply device that supplies a process gas to a plasma etching apparatus adjusts the flow rate of a process gas supplied from a gas A supply source 1-1 and a gas A supply source 1-1. Supplied from the gas A flow rate control device 2-1, the gas A shutoff valve 3-1, the gas A supply line 4-1, the gas B supply source 1-2, and the gas B supply source 1-2 that shut off the process gas. A gas B flow rate control device 2-2 for adjusting the flow rate of the process gas, a gas B cutoff valve 3-2 for shutting off the process gas supplied from the gas B supply source 1-2, and a gas B supply line 4-2 are provided. Prepare.

  The plasma etching apparatus also includes a plasma emission detector 9 for detecting plasma emission in the processing chamber 6, a pressure gauge 10 for measuring the pressure in the processing chamber 6, a source power source 7 for generating plasma, an antenna 8, and a processing chamber. Exhaust pump 13 for evacuating 6 to a vacuum state, exhaust control valve 12 for controlling the pressure of the processing chamber 7 to a constant level, process gas flow rate adjustment, process gas supply / stop timing control, and control for analyzing plasma emission components A controller 15 and a display monitor 16 for displaying the status of the control device are provided.

  The process gas supplied from the gas A supply line 4-1 is introduced into the processing chamber 6 in a vacuum state from a gas introduction port 5 attached to the processing chamber 6. The processing chamber 6 is maintained at a desired pressure value by controlling the exhaust control valve 12 and the exhaust pump 13 in accordance with the detection value of the pressure gauge 10. In the processing chamber 6, high-frequency power is supplied from the source power supply 7 via the antenna 8 to generate plasma. A chemical reaction due to plasma occurs on the wafer 14 that is the object to be processed, and etching proceeds. The generated reactive product and reactive gas are exhausted from the exhaust port 11.

  FIG. 2 is a diagram for explaining a method of measuring the gas arrival time to the processing chamber. Plasma is generated in a state where the process gas is supplied from the gas B supply source 1-2 to the processing chamber 6, and in this state, supply of the process gas from the gas A supply source 1-1 is started. The intensity of plasma emission of gas A is measured.

  The time required for the plasma A emission intensity of the gas A to increase to a predetermined value (t2−t1) from the start of the supply of the gas A (t2−t1), the plasma emission intensity of the gas A becomes constant (t3). The controller 15 measures the time until (t3−t1).

  Further, the supply of the process gas from the gas A supply source 1-1 is stopped (t4), the time required for the plasma A intensity of the gas A to decrease to a predetermined value (t5) (t5-t4), and the plasma of the gas A The controller 15 measures the time (t6-t4) until the light emission stops (t6).

  In the present invention, the time required for the gas to reach the processing chamber 6 after the gas supply is started (arrival time) is defined as the time required for the plasma emission intensity to reach 10%, and the gas supply is stopped. Then, the time for the gas in the processing chamber 6 to decrease (decrease time) is defined as the time required for the plasma emission intensity to reach 50%.

  3A and 3B are diagrams illustrating a method for measuring the gas arrival time and the gas decrease time. First, the processing chamber 6 and the gas supply lines 4-1 and 4-2 are exhausted (S1). Next, the gas B cutoff valve 3-2 is opened (S2). Next, the flow rate of the gas B supply line 4-2 is set in the gas B flow rate control device 2-2, and the gas B is introduced into the processing chamber 6 (S3). Next, power is output from the source power source 7 to the antenna 9 to generate plasma in the processing chamber 6 (S4).

  Next, the gas A cutoff valve 3-1 is opened (S5). Next, at time t1, the flow rate of the gas A supply line 4-1 is set in the gas A flow rate control device 2-1, the gas A is introduced into the processing chamber 6, and time measurement is started by the controller 15 (S6). . Next, measurement of gas components in the processing chamber 6 is started by the plasma emission detector 9 (S7). Next, at the time (t2) when the gas component supplied from the gas A supply line 4-1 is detected by the plasma light emission detector 9, the controller 15 acquires the elapsed time (t2-t1) (S8). Next, it is monitored by the plasma emission detector 9 that the gas component supplied from the gas A supply line 4-1 in the processing chamber 6 is stabilized (S9). Next, the elapsed time (t3-t1) is acquired by the controller 15 at the time (t3) when the gas component supplied from the gas A supply line 4-1 is stabilized (S10).

  Next, the controller 15 waits until a predetermined time elapses (S11). Next, at time t4, the flow rate of the gas A flow control device 2-1 is reduced to zero and the gas A cutoff valve 3-1 is closed (S12). Next, the plasma emission detector 9 monitors that the gas component supplied from the gas A supply line 4-1 in the processing chamber 6 decreases (S13). Next, when the gas component supplied from the gas A supply line 4-1 has decreased to 50% (t5), the controller 15 acquires the elapsed time (t5-t4) (S14). Next, it is monitored that the gas component supplied from the gas A supply line 4-1 in the processing chamber 6 is eliminated by the plasma emission detector 9 (S15). When the gas component supplied from the gas A supply line 4-1 is no longer detected (t6), the controller 15 acquires the elapsed time (t6-t4) (S16). Next, the flow rate of the gas B flow control device 2-2 is reduced to zero and the gas B cutoff valve 3-2 is closed (S17).

  Next, the processing chamber 6 and the gas supply lines 4-1 and 4-2 are exhausted (S18). Next, the elapsed time (t2-t1, t3-t1, t5-t4, t6-t4) in the gas A supply line 4-1 is displayed on the display monitor 16, and these data are held in the controller 15. (S19).

  FIG. 4 is a diagram illustrating a measurement procedure and a measurement result of the gas arrival time. 4A is a diagram showing a gas supply procedure, FIGS. 4A to 4E are diagrams showing the procedure in waveform, and FIG. 4F is a diagram showing measurement results.

  In this example, gas B is supplied from the gas B supply line 4-2 for 10 seconds in step 1 to generate plasma discharge, and gas A is supplied from the gas A supply line 4-1 for 10 seconds in step 2 to reach the gas arrival time. Measure. According to the measurement result, the gas A supply line 4-1 starts gas supply and reaches the processing chamber 6 for 2 seconds, and it takes 3 seconds for the gas supply to stabilize. Further, the gas A supply line 4-1 takes 2 seconds until the gas starts to decrease in the processing chamber 6 after the gas supply is stopped, and it takes 3 seconds until the gas in the processing chamber 6 runs out.

  The gas arrival time of the gas B supply line 4-2 can be measured by replacing the gas A supply line 4-1 and the gas B supply line 4-2 in the above-described procedure.

  FIG. 5 is a diagram showing the gas arrival times of the gas A supply line 4-1 and the gas B supply line 4-2 measured in this way. As described above, it is determined that the gas has arrived when the gas component in the plasma emission has increased by 10%, and is stable when the gas component in the plasma emission does not change by more than 10% in one second after the increase. Judge that In the example of FIG. 5, the arrival time of gas A is 2 seconds, and the arrival time of gas B is 1 second.

  FIG. 6 is a diagram for explaining a process gas supply method. First, processing conditions including step time, gas A flow rate, gas B flow rate, and source power are set in the controller 15 (S20). Next, the process gas arrival times of the gas A supply line 4-1 and the gas B supply line 4-2, which are measured in advance, are set in the controller 15 (S21).

  The controller 15 includes a flow rate value of the gas A flow rate control device 2-1, an open / close state of the gas cutoff valve 3-1, a flow rate value of the gas B flow rate control device 2-2, an open / close state of the gas cutoff valve 3-2, And the output timetable of the source power supply 7 is generated (S22).

  Next, initial states of the gas A cutoff valve 3-1 and the gas B cutoff valve 3-2 are output (S23). Next, the initial flow rates of the gas A flow rate control device 2-1 and the gas B flow rate control device 2-2 are output (S24). Next, the initial power is output from the source power supply 7 to the antenna 8 (S25). Next, the controller 15 starts the time measurement process and starts counting the step time (S26). Next, the controller 15 outputs the gas A flow rate control device 2-1, the gas A cutoff valve 3-1, the gas B flow rate control device 2-2, the gas B cutoff valve 3-3, and the output of the source power supply 7 according to the output timetable. Is changed (S27). The controller 15 monitors the elapsed time, and ends the process when the step time elapses (S28).

  In this example, processing conditions and arrival time data are set in the controller 15 in advance, but they may be input directly from an external input device or transferred from another storage medium to the controller 15. Further, although the controller 17 generates the output timetable, the timetable may be generated in another system and the generated timetable may be transferred to the controller 17.

  FIG. 7 is a diagram illustrating an example of the gas flow rate and the gas emission intensity supplied via the gas cutoff valve. As shown in FIG. 7A, the gas A starts to be supplied 2 seconds earlier than the start point of Step n, and stops supplying 2 seconds earlier than the end point of Step n. As a result, as shown in FIG. 7B, the gas A reaches the processing chamber at the start point of step n and decreases (falls) to 50% at the end point of step n.

  Similarly, as shown in FIG. 7C, the gas B starts to be supplied one second earlier than the start point of step n, and stops supplying one second earlier than the end point of step n. As a result, as shown in FIG. 7C, the gas B reaches the processing chamber at the start point of Step n and decreases (falls) to 50% at the end point of Step n.

  FIG. 8 is a diagram illustrating another example in which gas is switched and supplied to the processing chamber. As shown in FIG. 8A, the gas A starts to be supplied 2 seconds earlier than the start point of step n, and stops supplying 2 seconds earlier than the end point of step n. As a result, as shown in FIG. 8B, the gas A reaches the processing chamber at the start point of step n and decreases to 50% at the end point of step n. Similarly, as shown in FIG. 8C, the gas B starts to be supplied one second earlier than the start point of step n + 1, and stops supplying one second earlier than the end point of step n + 1. As a result, as shown in FIG. 7D, the gas B reaches the processing chamber at the start point of step n + 1 and decreases to 50% at the end point of step n + 1. That is, the supply lines for gas A and gas B can be switched.

  FIG. 9 is a diagram for explaining the second embodiment. The example shown in FIG. 9 differs from the example of FIG. 1 in that a plurality of gas inlets (5-1, 5-2) having different flow conditions are provided.

  FIG. 10 is a diagram illustrating an example in which gas is switched and supplied to the processing chamber. In the example of this figure, the gas arrival time of the gas A supply line 4-1 is 2 seconds, and the gas arrival time of the gas B supply line 4-2 is 4 seconds. For this reason, when the gas supply of the gas A supply line 4-1 is stopped 2 seconds earlier and the gas supply of the gas B supply line 4-2 is started 4 seconds earlier, the flow conditions are different at a plurality of gas introduction ports. The process gas can be continuously supplied into the processing chamber 6.

  FIG. 11 is a diagram illustrating an example in which the supply timing of the gas B is intentionally changed. In the example of this figure, the gas arrival time of the gas A supply line 4-1 is 2 seconds, and the gas arrival time of the gas B supply line 4-2 is 4 seconds. The gas supply of the gas A supply line 4-1 starts 3 seconds earlier and stops 2 seconds earlier. In addition, the gas supply of the gas B supply line 4-2 starts 5 seconds earlier and stops 4 seconds earlier. Thus, the arrival of the process gas into the processing chamber 6 can be controlled for each gas supply line.

  As described above, according to the embodiment of the present invention, a plurality of gas supply paths having different gas arrival times into the vacuum processing chamber due to different shapes of process gas inlets or gas pipe volumes are provided. In the semiconductor manufacturing apparatus, the time required for the process gas to reach the vacuum processing chamber in each gas supply path is grasped, and the timing for supplying and stopping the process gas is adjusted based on the grasped time. For this reason, the process gas can be supplied to the vacuum processing chamber at an optimal timing. For this reason, a uniform plasma process can be performed on the silicon wafer as the object to be processed. Moreover, the gas amount to be used can be reduced by optimizing the start and stop timing of the gas supply.

It is a figure which shows the process gas supply apparatus concerning 1st Embodiment. It is a figure explaining the method to measure the gas arrival time to a process chamber. It is a figure explaining the measuring method of gas arrival time and gas reduction time. It is a figure explaining the measuring method of gas arrival time and gas reduction time. It is a figure which shows the measurement procedure and measurement result of gas arrival time. It is a figure which shows the gas arrival time of the gas A supply line 4-1 and the gas B supply line 4-2. It is a figure explaining the supply method of process gas. It is a figure showing the example of the gas flow volume supplied via a gas cutoff valve, and gas emission intensity. It is a figure explaining the example which switches and supplies gas to a process chamber. It is a figure explaining 2nd Embodiment. It is a figure explaining the example which switches and supplies gas to a process chamber. It is a figure explaining the example which changed the supply timing of gas B intentionally.

Explanation of symbols

1-1 Gas A Supply Source 1-2 Gas B Supply Source 2-1 Gas A Flow Control Device 2-2 Gas B Flow Control Device 3-1 Gas A Shutoff Valve 3-2 Gas B Shutoff Valve 4-1 Gas A Supply Line 4-2 Gas B supply line 5 Gas inlet 6 Processing chamber 7 Source power supply 8 Antenna 9 Plasma emission detector 10 Pressure gauge 11 Exhaust outlet 12 Exhaust control valve 13 Exhaust pump 14 Wafer 15 Controller 16 Display monitor

Claims (4)

A vacuum processing chamber with a reduced pressure inside,
A gas supply source for supplying a process gas to the vacuum processing chamber ;
A plasma generating apparatus for generating plasma by supplying high-frequency energy to the process gas supplied to the vacuum processing chamber ;
A gas supply line for supplying the process gas supplied from the gas supply source to the vacuum processing chamber via a gas flow rate control device, a gas circuit breaker, and a gas supply line;
A plasma emission detector for detecting plasma onset light of the vacuum processing chamber,
A control controller for performing flow rate control of the process gas, timing control of supply and stop of the process gas, and analysis of the plasma emission,
The control controller sets the process gas as the time required for the plasma emission to reach a predetermined intensity as the time required for the process gas to reach the vacuum processing chamber after the supply of the process gas is started. Measured in advance as the time required for the plasma emission to reach a predetermined intensity, the time required for the process gas in the vacuum processing chamber to decrease after the supply of gas is stopped, and only the pre-measured arrival time The plasma processing apparatus is characterized in that the supply of the process gas is quickly started at the gas flow rate of the processing condition and the supply of the process gas is quickly stopped for a pre-measured decrease time . The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein the gas supply sources supply different process gases to the vacuum processing chamber via gas supply pipes having different pipe volumes . A vacuum processing chamber with a reduced pressure inside,
A gas supply source for supplying a process gas to the vacuum processing chamber ;
A plasma generating apparatus for generating plasma by supplying high-frequency energy to the process gas supplied to the vacuum processing chamber ;
A gas supply line for supplying the process gas supplied from the gas supply source to the vacuum processing chamber via a gas flow rate control device, a gas circuit breaker, and a gas supply line;
A plasma emission detector for detecting plasma onset light of the vacuum processing chamber,
In a plasma processing method using a plasma processing apparatus, comprising a flow rate control of the process gas, a timing control of supply and stop of the process gas, and a control controller for analyzing the plasma emission ,
Measured in advance as the time required for the plasma emission to reach a predetermined intensity, which is the time required for the process gas to reach the vacuum processing chamber after starting the supply of the process gas,
The supply of the process gas is started as early as the gas flow rate of the processing conditions for the pre-measured arrival time,
Measured in advance as a time required for the plasma emission to reach a predetermined intensity, which is a time for the process gas in the vacuum processing chamber to decrease after the supply of the process gas is stopped,
A plasma processing method, wherein the supply of the process gas is quickly stopped for the previously measured decrease time . The plasma processing method according to claim 3, wherein
The plasma processing method according to claim 1, wherein the gas supply sources supply different process gases to the vacuum processing chamber via gas supply pipes having different pipe volumes .

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