JP5121684B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing method suitable for performing surface processing of a semiconductor substrate or the like using plasma.

  Due to miniaturization of recent semiconductor elements, higher accuracy in dimensional accuracy, that is, CD (Critical Dimension) accuracy is required for an etching process for transferring a mask formed by lithography onto a lower layer film. In addition to high CD controllability in mass production sites, ensuring CD reproducibility is an important issue.

  In general, the factors that cause the CD to fluctuate in the etching process are that reaction products generated from the material to be processed adhere to the inner wall of the etching chamber, the chamber inner member is consumed due to long-term use, the temperature of the chamber inner member fluctuates, For example, the probability of radical adhesion to the inner wall of the chamber changes, and the plasma state that affects the etching performance fluctuates.

  Conventional plasma processing equipment is equipped with a temperature controller in the vacuum chamber in order to suppress temperature fluctuations in the chamber, the temperature of the vacuum chamber is adjusted, and the temperature controller cannot be installed. The temperature of windows and the like has been controlled by a method such as performing preliminary discharge before processing the material to be processed. However, since the standby time between processes changes, the temperature in the chamber during standby changes, and temperature control by preliminary discharge may not be performed stably.

  As the degree of integration of semiconductor integrated circuits increases, long-term suppression of CD fluctuation is required. It is an object of the present invention to provide a plasma processing apparatus that stabilizes the temperature of the internal members of the apparatus and has little CD fluctuation.

The plasma processing apparatus of the present invention, a processing chamber for evacuation device is arranged inside are connected to the vacuum container interior can be vacuum, an upper portion of the vacuum vessel, are arranged mounted above the processing chamber and a dielectric-made plate member, a gas supply device for supplying a gas into the processing chamber, is disposed in the processing chamber, a substrate electrode capable or one temperature control can place the workpiece, the In the plasma processing apparatus, comprising: an electric field introducing means for introducing an electric field for forming plasma in the processing chamber from a dielectric plate member; and a power supply for supplying the electric field to the electric field introducing means. A temperature sensor for detecting the temperature of the body plate member and a hot air fan unit for introducing warm air into the dielectric plate member, the dielectric plate member being sealed with a cover on the outside, Inside the hot air flow Inlet for loading and unloading the warm air from the emission unit and has the hot-air fan unit linked exhaust port has the structure warm air is circulated from the hot air fan unit, from said temperature sensor The temperature of the dielectric plate member can be adjusted by adjusting the operation of the hot air fan unit based on the signal.

According to the plasma processing apparatus of the present invention, the temperature variation of a dielectric plate member placed on the upper side of the processing chamber, such as a dielectric window for introducing electromagnetic waves for plasma generation, is suppressed, and etching is performed. Since fluctuations in the adhesion probability of radicals and the like that affect performance are suppressed, there is an effect that CD fluctuations can be suppressed.

  A plasma processing apparatus using a microwave ECR (Electron Cyclotron Resonance) etching apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 shows the configuration of a plasma processing apparatus according to the first embodiment of the present invention. A shower plate 102 (for example, made of quartz or yttria) and a dielectric window 103 (for example, made of quartz) for introducing an etching gas into the vacuum container 101 and a dielectric window 103 (for example, made of quartz) are installed on the upper part of the vacuum container 101 whose upper part is opened and sealed. Thus, the processing chamber 104 is formed.

  A heater 122 is installed outside the vacuum vessel 101 and is connected to a heater controller 123. A temperature sensor 124 is installed in the vacuum vessel 101, and the signal is transmitted to the heater controller 123, and the output of the heater 122 is controlled so that the inner wall of the vacuum vessel 101 reaches an arbitrary temperature. A gas supply device 105 for flowing an etching gas is connected to the shower plate 102. In addition, a vacuum exhaust device (not shown) is connected to the vacuum vessel 101 via a vacuum exhaust port 106.

  A waveguide 107 (or an antenna) that radiates electromagnetic waves is provided above the dielectric window 103 in order to transmit power for generating plasma to the processing chamber 104. The electromagnetic wave transmitted to the waveguide 107 (or antenna) is oscillated from the electromagnetic wave generating power source 109. The frequency of the electromagnetic wave is not particularly limited, but a microwave of 2.45 GHz is used in this embodiment. A magnetic field generating coil 110 that forms a magnetic field is provided on the outer peripheral portion of the processing chamber 104, and the electric power oscillated from the electromagnetic wave generation power source 109 is plasma in the processing chamber 104 due to the interaction with the formed magnetic field. Is generated.

  In addition, a wafer mounting electrode 111 is provided below the vacuum vessel 101 so as to face the shower plate 102. The wafer mounting electrode 111 has an electrode surface covered with a sprayed film (not shown), and a DC power supply 116 is connected through a high frequency filter 115. Further, a high frequency power supply 114 is connected to the wafer mounting power supply 111 via a matching circuit 113.

  The wafer mounting electrode 111 has a coolant channel 117 and is connected to the temperature controller 118, and has a heater 119 and is connected to the heater controller 120. Further, a temperature sensor 121 is installed on the wafer mounting electrode 111, and the signal is transmitted to the heater controller 120 to control the heater 119 output and the temperature of the refrigerant so that the wafer 112 temperature becomes a desired temperature. The set temperature of the adjuster 118 is controlled.

  The wafer 112 transferred into the processing chamber 104 is adsorbed onto the wafer mounting electrode 111 by the electrostatic force of the DC voltage applied from the DC power source 116 and the temperature is adjusted, and a desired etching gas is supplied by the gas supply device 105. After that, the inside of the vacuum chamber 101 is set to a predetermined pressure, and plasma is generated in the processing chamber 104. By applying a high frequency power from a high frequency power source 114 connected to the wafer mounting electrode 111, ions are drawn from the plasma into the wafer, and the wafer 112 is etched.

  Conventionally, the temperature in the etching chamber has been controlled to an arbitrary temperature by the heater 122 on the inner wall of the vacuum vessel 101 and the heater 119 and the temperature controller 118 for the wafer mounting electrode 111. However, the temperature of the shower plate 102 and the dielectric window 103, which occupy another large area as the surface area in the etching chamber, is not actively controlled. I was receiving.

  FIG. 2 shows the relationship between the temperature of the shower plate 102 and the CD value obtained at that time. It can be seen that the CD value has a good correlation with the temperature of the shower plate 102. In addition, it is known that the temperature of the dielectric window 103 has a correlation with the CD value except for the transient phenomenon, and it is necessary to stabilize the temperature of the shower plate 102 and the dielectric window 103 in order to always stabilize the CD value. is there. In the present invention, in order to control the temperature of the dielectric window 103 and the shower plate 102, a hot air unit 125 that introduces hot air into the waveguide 107 above the dielectric window 103 is connected.

  The hot air unit 125 is connected to the hot air unit controller 127. A metal mesh 133 is provided at the air outlet of the hot air unit 125 in order to prevent high-frequency electromagnetic waves from entering the hot air unit 125. In order to prevent the warm air introduced into the waveguide from flowing into the electromagnetic wave generating power source 109, a dielectric plate 134 is installed between the warm air unit 125 and the electromagnetic wave generating power source 109.

  The warm air flowing into the cavity resonator 108 via the waveguide 107 contacts the dielectric window 103, and thermal energy is transferred to the dielectric window 103. In addition, a hot air exhaust port 126 for exhausting hot air is provided at the upper part of the cavity resonator 108 (which may be another part such as a side part). The exhausted warm air may be directly released into the atmosphere, but for improved energy efficiency, the exhausted warm air is introduced into the warm air unit 125 through a pipe, and the warm air is circulated inside. Yes. The reason for using warm air here is that the dielectric window 103 and the shower plate 102 are heated to high temperatures (eg, 200 ° C. or more) due to heat input from the plasma. It is effective to cause convection.

  Therefore, it is possible to improve the efficiency of temperature control by using warm air rather than directly heating with a heater or the like. In order to monitor the temperature of the dielectric window 103, a temperature sensor 128 is installed on the cavity resonator 108. Here, the temperature sensor 128 may be directly connected to the dielectric window 103. However, in the case of this embodiment, the upper part of the dielectric window 103 is a transmission path for high-frequency electromagnetic waves, so that the influence on the high-frequency electromagnetic field is reduced. In order to reduce the temperature, an infrared measurement type temperature monitor 128 is installed as the temperature sensor 128.

  Here, when the dielectric window 103 is directly measured, the infrared ray to be used is a far infrared region having high sensitivity even at a relatively low temperature that is equal to or higher than the transmission wavelength region of the dielectric window 103. However, when the shower plate 102 is directly measured, the infrared ray to be used is an infrared wavelength (near infrared to mid-infrared) less than or equal to the transmission wavelength range of the dielectric window 103, and generally has a wavelength range of several μm. It becomes. In the case of this embodiment, the temperature of the shower plate 102 during plasma processing is usually higher than that of the dielectric window 103, and the temperature of the shower plate 102 can be measured. In order to directly measure the temperature of the shower plate 102 with high accuracy, an infrared measurement marker 129 is installed on the upper portion of the shower plate 102. The material of the infrared measurement marker 129 needs to have an absorption wavelength region in the infrared transmission wavelength region of the dielectric window 103 and the shower plate 102.

  In this case, the infrared wavelength of the infrared measurement type temperature monitor 128 is directly used by using a wavelength region that is a transmission wavelength for the dielectric window 103 and an absorption wavelength for the infrared measurement marker 129. It becomes possible to measure the temperature of the shower plate 102. The temperature signal measured by the infrared measurement type temperature monitor 128 is transmitted to the hot air unit controller 127, and the air volume or temperature of the hot air unit 125 is adjusted so that the dielectric window 103 or the shower plate 102 has a desired temperature. adjust. Here, more effective temperature adjustment is possible by setting the temperature range adjusted by the hot air unit 125 to room temperature to 300 ° C.

  As described above, in the embodiment of the present invention, the inner wall temperature of the vacuum vessel 101 is the heater 122, the temperature of the wafer mounting electrode 111 is the heater 119 and the temperature controller 118, and the dielectric window 103 or the shower plate 102 is heated. Each unit 125 can be controlled to a desired temperature, and the heater controller 120, the temperature controller 118, the heater controller 123, and the hot air unit controller 127 are further connected to the central temperature control unit 130.

  The central temperature control unit 130 is connected to an etching control unit 131 that controls the entire etching apparatus, and includes a temperature sensor 128 that monitors the dielectric window temperature, a temperature sensor 122 that monitors the vacuum vessel wall temperature, and a substrate electrode. The temperature signal measured by the temperature sensor 121 that monitors the temperature is signal-processed, the hot air unit 125 connected to the temperature sensor 128, the heater controller 123 connected to the temperature sensor 122, and the temperature sensor 121. Each of the heater controller 120 and the temperature controller 118 can be controlled.

  Each temperature control device can also perform temperature control other than the components to which they are directly connected in a complex manner. For example, the shower plate 102 loses thermal energy not only from the upper dielectric window 103 but also from the lower part of the etching chamber when the discharge is turned off. In order to suppress this loss of heat energy, not only the hot air unit 125 but also the heater 122, the heater 119, and the temperature controller 118 are set so that the temperature of the shower plate 102 or the dielectric window 103 is constant when the discharge is turned off. It is effective to adjust the temperature (mainly heating).

  Further, when heat loss from the lower part of the etching apparatus is dominant, it is also possible to dispose a material having a heat transfer coefficient lower than that of the material constituting the vacuum vessel 101 in the lower part of the apparatus. It is effective in suppressing the above.

FIG. 3 shows the time change of the temperature of the dielectric window 103 when the discharge is OFF when the dielectric window 103 is actually heated. It can be seen that in the case of heating, the temperature drop is suppressed compared to the conventional method. Although this result does not actually optimize the temperature control parameters, the temperature fluctuation of the shower plate 102 that can stabilize the CD can be achieved by using the above-described temperature control mechanism. .
In this embodiment, an example of temperature control using the hot air unit 125 has been described. However, only the temperature of the dielectric window 103 or the shower plate 102 is monitored by the infrared measurement type temperature monitor 128 to manage the apparatus state. Thus, determining whether or not actual processing is possible is also effective in improving the yield in device production.

  By controlling the temperature of the dielectric window 103 and the shower plate 102 using the hot air unit 125 according to the present invention, it is possible to stabilize the temperature of the components constituting the processing chamber 104 of the etching apparatus, and CD Since the stability can be improved, an etching process with low yield and little change with time is possible.

  Next, a plasma processing apparatus using an ICP (Inductively Coupled Plasma) etching apparatus according to a second embodiment of the present invention will be described with reference to FIG. The same points as in the first embodiment are omitted. A loop antenna 403 is installed above the dielectric window 103 on the processing chamber 104. The loop antenna 403 is connected to the plasma generating high frequency power supply 401 via the matching unit 402. A cover 404 is installed so as to seal the dielectric window 103 and the loop antenna 403.

  Plasma is generated in the processing chamber 104 by high-frequency energy introduced from the loop antenna 403 through the dielectric window 103. The cover 404 serves to prevent high-frequency electromagnetic waves from leaking to the outside and to retain hot air from the hot air unit 125 on the dielectric window 103.

  In this embodiment, as in the first embodiment, the temperature of the dielectric window 103 and the shower plate (not shown) is controlled by using the hot air unit 125, so that the components constituting the processing chamber 104 of the etching apparatus are controlled. Since the temperature can be stabilized and the CD stability can be improved, an etching process with less yield reduction and less change with time is possible.

  In the first and second embodiments, the cover surrounding the dielectric window also serves as a microwave transmission path and high-frequency leakage prevention, but the same effect can be obtained by providing a separate cover. In the present embodiment, only the ECR and ICP etching apparatuses are mentioned. However, in all apparatuses that generate plasma through a dielectric window using high-frequency transmission means such as an antenna, a cover is sealed outside the dielectric window. Since the temperature of the dielectric window can be controlled without affecting the high frequency by controlling the temperature of the dielectric window with hot air, the above-mentioned CD can be stabilized. There is an effect.

FIG. 1 is a longitudinal sectional view of a microwave ECR etching apparatus that is Embodiment 1 of the present invention. FIG. 2 is a characteristic diagram showing the relationship between the shower plate and CD variation. FIG. 3 is a characteristic diagram showing the influence of the presence or absence of heating of the dielectric window on the change in shower plate temperature with time. FIG. 4 is a longitudinal sectional view of an inductively coupled plasma etching apparatus that is Embodiment 2 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Vacuum container 102 Shower plate 103 Dielectric window 104 Processing chamber 105 Gas supply apparatus 106 Vacuum exhaust port 107 Waveguide 108 Cavity resonator 109 Electromagnetic wave generation power source 110 Magnetic field generation coil 111 Wafer mounting electrode 112 Wafer 113 Matching circuit 114 High-frequency power supply 115 Filter 116 DC power supply for electrostatic adsorption 117 Flow path for refrigerant 118 Temperature controller 119 Heater 120 Heater controller 121 Temperature sensor 122 Heater 123 Heater controller 124 Temperature sensor 125 Hot air unit 126 Hot air exhaust port 127 Hot air Unit controller 128 Infrared measurement type temperature monitor 129 Infrared measurement marker 130 Central temperature control unit 131 Etching apparatus control unit 132 Thermal insulation layer 133 Metal mesh 134 Dielectric Body plate 401 High frequency power source for plasma generation 402 Matching unit 403 Loop antenna 404 Cover

Claims (5)

A processing chamber disposed inside a vacuum vessel to which an evacuation device is connected and capable of depressurizing the interior ; a plate member made of a dielectric disposed on the upper portion of the vacuum chamber and placed above the processing chamber; a gas supply device for supplying a gas into the processing chamber, is disposed in the processing chamber, a substrate electrode capable or one temperature control can place the workpiece, the more the dielectric made of plate member In a plasma processing apparatus comprising: an electric field introducing means for introducing an electric field for forming plasma in a processing chamber ; and a power supply for supplying the electric field to the electric field introducing means .
A temperature sensor for detecting the temperature of the dielectric plate member, and a hot air fan unit for introducing warm air into the dielectric plate member, and the dielectric plate member is hermetically sealed by a cover. A hot air from the hot air fan unit that has an introduction port for taking in and out the hot air from the hot air fan unit and an exhaust port connected to the hot air fan unit. And a temperature adjustment of the dielectric plate member by adjusting the operation of the hot air fan unit based on a signal from the temperature sensor. The plasma processing apparatus according to claim 1 ,
The plasma processing apparatus, wherein the temperature sensor is of an infrared measurement type. The plasma processing apparatus according to claim 2 , wherein
It has an infrared measurement marker disposed on the dielectric plate member, and the infrared measurement marker material has an absorption wavelength region in the infrared transmission wavelength region of the dielectric plate member. A plasma processing apparatus for measuring a temperature of the dielectric plate member by the temperature sensor . In the plasma processing apparatus in any one of Claims 1 thru | or 3 ,
And means for forming a magnetic field, and wherein the electric field to form the plasma be of microwave, cover enclosing said dielectric made plate member is a transmission path of the electric field of the microwave Plasma processing equipment. The plasma processing apparatus according to claim 4 , wherein
The waveguide field supply means for introducing an electric field for a dielectric made of a plate member for generating the plasma and said hot air fan unit is connected to the air blowing port of the hot air fan unit that the metal mesh is provided to prevent the electric field enters the temperature wind fan unit, wherein the waveguide, the warm air introduced into the waveguide from flowing into the power supply A plasma processing apparatus comprising a dielectric plate for preventing the plasma processing apparatus.

Images