JP2010192751A - Plasma processing method - Google Patents

Abstract

By performing a stable plasma process on a substrate to be processed, the generation of foreign particles having a fine particle diameter from a processing chamber is reduced, and the production efficiency of a semiconductor element is improved.
A vacuum processing chamber provided with a gas introduction device for introducing a processing gas, a microwave power source disposed in the vacuum processing chamber and supplying microwave energy to the introduced processing gas to generate plasma, A plasma processing method comprising a sample stage disposed in the vacuum processing chamber, supplying a high-frequency voltage to the sample stage, attracting ions in the plasma, and subjecting the sample placed on the sample stage to plasma processing In the first step of generating a plasma in the vacuum processing chamber by supplying a low power of 8 to 200 W, which is an energy capable of igniting the plasma as the energy of the microwave, and after confirming the generation of the plasma, And a second step of generating plasma by supplying a normal value capable of plasma processing by stably generating plasma as wave power.
[Selection] Figure 1

Description

  The present invention relates to a plasma processing method, and more particularly to a plasma processing method capable of suppressing the generation of foreign matter.

  In the manufacture of semiconductor devices, foreign matter on the submicron level is generated, which adversely affects each manufacturing process. For example, in a semiconductor device manufacturing process, if foreign matter adheres to a wafer on which a semiconductor device is formed, the attached foreign matter serves as a mask to form an erroneous electric circuit, resulting in a reduction in manufacturing yield.

  Foreign matter is often generated due to gas introduction, electrostatic adsorption voltage application, application of high-frequency power for plasma generation, temperature change, and the like.

  Among these, as a method of reducing the generation of foreign matter due to the application of high-frequency power, when generating plasma, first, the minimum high-frequency power necessary for plasma generation is supplied to the gas, after generating the minimum plasma, A technique is known that suppresses the generation of foreign matter on a substrate to be processed by increasing high-frequency power and generating plasma necessary for processing the substrate to be processed (see Patent Document 1).

JP 2005-116821 A

  As semiconductor elements are miniaturized, there is a need to reduce the fine particle size foreign matter generated from semiconductor manufacturing equipment. As a solution to reduce the generation of foreign matter on the object to be processed, first, it is necessary for plasma generation. It is possible to suppress the generation of foreign matter on the substrate to be processed by supplying the minimum high-frequency power to the gas, generating the minimum plasma, and then generating the plasma necessary to increase the power and processing the substrate to be processed. As described above.

  As described above, Patent Document 1 discloses a technique for suppressing generation of foreign matter on a substrate to be processed. However, high-frequency power required for plasma generation, or high-frequency bias power supplied to the sample mounting table for processing the substrate to be processed, and the relationship between the amount of foreign matter generated and stable plasma processing for the substrate to be processed In addition, the conditions for reducing the generation of fine particles having a small particle diameter from the processing chamber are not presented.

  Also, during plasma processing of wafers, the amount of power required for plasma ignition due to gas species for plasma processing, gas flow rate, processing pressure, or accumulation of reaction products in the processing chamber due to stacking of plasma processing, etc. Also changes. For this reason, the number of foreign matters on the wafer generated during plasma ignition also varies.

  The present invention has been made in view of these problems, and by performing stable plasma processing on a substrate to be processed, the generation of foreign particles having a fine particle diameter from the processing chamber is reduced, and the production of semiconductor elements is achieved. It improves efficiency.

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

  A vacuum processing chamber provided with a gas introducing device for introducing a processing gas; a microwave power source that is disposed in the vacuum processing chamber and supplies plasma energy to the introduced processing gas to generate plasma; and the vacuum processing chamber In the plasma processing method, the method includes: supplying a high-frequency voltage to the sample stage, attracting ions in the plasma, and subjecting the sample placed on the sample stage to plasma treatment; A first step of generating a plasma in the vacuum processing chamber by supplying a low power of 8 to 200 W, which is an energy capable of igniting the plasma, as a wave energy; and after confirming the generation of the plasma, A second step of generating a plasma by supplying a normal value capable of stably generating plasma and performing plasma processing.

  Since the present invention has the above-described configuration, stable plasma processing can be performed on a substrate to be processed, dust generation of fine particles having a small particle diameter from the processing chamber can be reduced, and semiconductor device production efficiency can be improved. Can be improved.

It is a figure explaining the plasma processing apparatus concerning this embodiment. It is the figure which showed the result of having measured the foreign material number on the to-be-processed substrate in a 1st step and a 2nd step. It is the figure which showed the result of having measured the foreign material number on the to-be-processed substrate in a 1st step and a 2nd step. FIG. 4 is a diagram illustrating a foreign substance evaluation result when a high-frequency bias power is applied in the process of the second step.

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

  FIG. 1 is a diagram illustrating a plasma processing apparatus according to the present embodiment. In the example of this figure, a microwave plasma etching apparatus using a microwave and a magnetic field as means for forming plasma is shown.

  In this apparatus, an etching gas is supplied to the etching chamber 101 from a gas introduction means 104 through a transmission window 105 having a porous structure, for example, quartz. Further, the microwave oscillated by the microwave generator 115 is introduced into the etching processing chamber 101 from the microwave introduction window 108 via the matching unit 106 and the waveguide 107, and the etching gas in the processing chamber is turned into plasma. For high-efficiency discharge, a solenoid coil 109 for generating a magnetic field is arranged around the etching processing chamber, a magnetic field of 0.0875 Tesla is generated in the processing chamber, and high-density plasma is generated in the processing chamber using electron cyclotron resonance. .

  A sample stage 103 is provided in the etching processing chamber 101. A substrate 102 to be processed is placed on the sample stage and etched by plasma generated by microwaves. A high frequency power supply 113 is connected to the sample stage 103 on which the object to be processed is installed, and a high frequency bias voltage of 400 kHz to 13.56 MHz is applied. An adsorption electrode is provided on the surface of the sample stage 103, and an electrostatic adsorption force is generated by applying a DC voltage to the electrode from the electrostatic adsorption power source 110, and the substrate 102 is treated by the electrostatic chuck action. Adsorb to 103.

  Further, a groove is formed on the surface of the sample table 103, and a flow path (not shown) is formed between the back surface of the substrate to be processed 102 fixed to the surface of the sample table. A cooling gas such as He, Ar, O 2 or the like is supplied to the flow path from the cooling gas supply port 112 so that the inside of the flow path can be maintained at a predetermined pressure.

  The heat of the substrate to be processed 102 is transferred to the surface of the sample stage 103 through gas heat transfer in the flow path and heat conduction from the contact surface. Thereby, the to-be-processed substrate 102 is maintained at a constant temperature. In order to adjust the temperature of the substrate 102 to be processed, a heat medium whose temperature is controlled to a predetermined temperature by the heat medium circulator 111 is circulated in the refrigerant circulation channel embedded in the sample stage 103.

  An insulating cover 114 made of ceramic or quartz is disposed around the substrate to be processed 102. Note that the etching gas introduced into the etching chamber 101 is exhausted outside the etching chamber 101 by an exhaust pump and an exhaust pipe (not shown) after the etching is completed.

  The light emission detector 116 is used for confirming plasma generation when supplying the microwave to the processing chamber to turn the etching gas into plasma. The light emission detection information detected by the light emission detector is used for output control of the microwave generator and the high frequency bias power supply via a device control device (not shown).

  When performing plasma processing using the plasma processing apparatus shown in FIG. 1, first, in the first step, for example, an etching gas is supplied at a predetermined flow rate into the processing chamber, and the exhaust speed of the vacuum exhaust system is controlled to control the processing chamber. Then, the microwave power source 115 is turned on and predetermined power (low power) is applied. Thereafter, in the second step, after confirming that the etching gas is turned into plasma by the light emission detector 116, the microwave power is increased to a normal value (steady value).

As a result, stable plasma can be generated from the low power input in the first step to the plasma ignition to the normal value power input in the second step. For this reason, it is possible to suppress the generation of foreign matter due to the non-ignition of plasma or the separation of foreign matter from the inner wall of the vacuum processing chamber by the action of an electric field when unstable plasma is generated. 3 shows the result of measuring the number of foreign matters on the substrate to be processed in the first step for the purpose and the second step of plasma processing the substrate to be processed with a predetermined microwave output.

  The foreign matter was evaluated under the following conditions. A predetermined current is supplied to the solenoid coil, Ar gas is supplied at a gas flow rate of 150 cc / min, the gas pressure in the etching chamber is adjusted to 0.4 Pa, and then the microwave output is set to 0 W to 800 W as the first step. After the plasma ignition was confirmed (except for 0 W), the plasma treatment was performed by supplying normal microwave power (steady value).

  FIG. 2 also shows the dependence of the number of foreign matter generation on the high frequency bias power supplied to the processing substrate in addition to the number of foreign matter generation on the microwave power supplied to the processing chamber in the first step.

  Further, FIG. 3 shows the number of foreign matters generated with respect to the microwave power (first step power) (the number of foreign matters is 0.6 μm or more on a 300 mm substrate-like shape using a laser type foreign matter inspection apparatus. (Evaluation was based on the number of foreign substances, and the evaluation result when the microwave output in the first step was set to 0 w was displayed in arbitrary units with the number of foreign substances being 100).

  As shown in FIG. 2, simply generating plasma with minimal power does not mean minimizing the number of foreign particles generated. Moreover, the foreign substance evaluation result obtained by the combination of the applied power value of the first step and the high frequency applied power value of the second step is not determined at the same point.

  As shown in FIG. 2, in the first step, the number of foreign matters generated is large when the microwave power is 0 W and when the microwave power is 800 W. In the first step, the microwave power is set to 8 W to 200 W, and the plasma processing is executed in the second step after confirming the plasma generation, whereby only the conventional second step processing is performed (no first step). When the first step is present, the number of foreign matters can be reduced to 42 to 35 (arbitrary units) as compared to the number of foreign matters 100 (arbitrary units).

  FIG. 4 is a diagram showing a foreign substance evaluation result when a high frequency bias power is applied together in the process of the second step in addition to the method of applying the microwave in two steps. In the figure, the solid line indicates the relationship between the microwave power applied to the vacuum processing chamber in the first step and the number of foreign substances (the high frequency bias power applied to the substrate to be processed is 0 W), and the broken line indicates the vacuum processing chamber in the first step. The relationship between the microwave power applied to the substrate and the number of foreign substances (the high frequency bias power applied to the substrate to be processed is 50 W) is shown.

  When both are compared, it can be seen that the number of foreign substances can be reduced to 1/6 or less when the microwave applied power applied in the first step is in the range of 8 W to 200 W. This is generated by the above-mentioned plasma non-ignition or dust generation due to electric field action at the time of unstable plasma generation, for example, dust generation due to peeling of deposits on the inner wall of the etching process, or a bias power source applied to the sample stage. The plasma sheath on the upper surface of the substrate to be processed is considered to suppress the adhesion of foreign matter on the surface of the substrate to be processed.

  As described above, the present embodiment includes the first plasma processing step performed with low power and the second plasma processing step performed after confirmation of plasma generation in the step.

  As a result, stable plasma processing can be performed, and fine particulate foreign matter adhering to the substrate to be processed can be greatly reduced. Also, by performing the two plasma treatment steps, it is possible to suppress dust generation due to electric field action when plasma is not ignited or unstable plasma is generated, for example, dust caused by separation of deposits on the inner wall of the etching process. it can. Moreover, adhesion of foreign matter on the surface of the substrate to be processed can be suppressed by the plasma sheath formed on the upper surface of the substrate to be processed, which is formed by a bias power source applied to the sample stage.

101 Etching chamber 102 Substrate 103 Sample stage 104 Gas introduction means 105 Transmission window 106 Matching unit 107 Waveguide 108 Microwave introduction window 109 Solenoid coil 110 Electrostatic adsorption power supply 111 Heat medium circulator 112 Cooling gas supply port 113 High frequency Power supply 114 Insulation cover 115 Microwave power supply 116 Luminescence detector

Claims (2)

A vacuum processing chamber provided with a gas introduction device for introducing a processing gas; a microwave power source that is disposed in the vacuum processing chamber and supplies plasma energy to the introduced processing gas to generate plasma; and the vacuum processing chamber In the plasma processing method of performing a plasma treatment on a sample placed on the sample stage by supplying a high-frequency voltage to the sample stage and attracting ions in the plasma,
A first step of generating a plasma in the vacuum processing chamber by supplying a low power of 8 to 200 W which is an energy capable of igniting the plasma as the energy of the microwave;
A plasma processing method comprising: a second step of generating plasma by supplying a normal value capable of plasma processing by stably generating plasma as the microwave power after confirming the generation of the plasma . The plasma processing method according to claim 1,
A plasma processing method, wherein high-frequency power for ion attraction is supplied to the sample stage when performing the processing of the first step.

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