JP2012049166A - Vacuum processing apparatus - Google Patents

Abstract

In a plasma processing apparatus, the focus ring is cooled to a temperature equivalent to that of a sample with a simple structure, so that the consumption of the focus ring is suppressed and the etching characteristics of the outer peripheral portion of the sample are kept good for a long period of time.
A vacuum processing chamber, a sample stage, a first electrostatic adsorption layer for electrostatically adsorbing a sample, and a second electrostatic adsorption layer for electrostatically adsorbing a focus ring. 21 and means 24, 25 for supplying heat transfer gas to the back surface of the sample 3, heat transfer gas supply grooves 27, 28, 29 on the surfaces of the first and second electrostatic adsorption layers 20, 21, respectively. In order to supply the heat transfer gas at different pressures to the center side of the sample 3 and the outer periphery side of the sample 3, the heat treatment gas supply means 24, 25 of the two systems is used. The hot gas is branched into the heat transfer gas supply groove 29 on the mounting surface of the focus ring 14 by the heat transfer gas supply path 26, and the focus ring cooling heat transfer gas is shared with the wafer cooling heat transfer gas.
[Selection] Figure 2

Description

  The present invention relates to a vacuum processing apparatus for processing a sample such as a semiconductor wafer.

  In semiconductor device manufacturing processes, plasma processing apparatuses are widely used in processes such as film formation and etching. These plasma processing apparatuses are required to have high precision processing performance and mass production performance corresponding to devices to be miniaturized. From the viewpoint of mass productivity, the wafer size has been expanded, and at present, 12-inch wafers are the mainstream. Further, since productivity is improved by improving the yield, temperature control is important for making the etching rate uniform.

  For example, in Patent Document 1, heat transfer gas for sample cooling is supplied by two systems having different pressures, and the heat transfer characteristics are changed in the sample plane. Since this method has two paths for the heat transfer gas for sample cooling, the temperature distribution on the sample surface can be controlled to be uniform.

  In recent years, since many devices are produced from one wafer, devices are produced as far as possible to the outer peripheral edge of the wafer. Therefore, it is necessary to prevent the deterioration of the etching characteristics even at the outer peripheral edge of the wafer. However, since the temperature of the focus ring rises due to heat input from the plasma, the outer peripheral portion of the sample is affected by the radiant heat from the focus ring, resulting in poor etching characteristics.

  In particular, when used under conditions where a high bias power is applied, the temperature of the focus ring reaches 500 ° C. or more, so that the sample is strongly influenced by the radiant heat from the focus ring. According to Stefan-Boltzmann's law, the energy of the radiant heat is proportional to the fourth power of the absolute temperature. Therefore, in order to reduce the influence of the radiant heat, it is effective to cool the focus ring.

  Furthermore, the focus ring is scraped by the colliding ions. As the focus ring is cut, the etching characteristics at the outer peripheral edge of the wafer deteriorate with time. When the temperature of the focus ring is high, depot deposits do not adhere, and wear of the focus ring proceeds at a considerable rate.

  If the height of the sheath at the outer peripheral edge of the wafer is greatly lowered due to wear of the focus ring, the yield at the outer peripheral edge of the wafer deteriorates, and the focus ring needs to be replaced. If the replacement period is short, the running cost also becomes high, so the cooling of the focus ring is important not only for preventing the etching characteristics from deteriorating but also for improving the running cost.

  As a conventional technique, for example, in Patent Document 2, the sample stage cover is cooled by using the heat transfer gas supplied from the center of the sample stage to the back side of the sample together with the sample stage cover that protects the sample stage.

  Patent Document 3 discloses a method in which a focus ring is installed on the outer periphery of an electrostatic chuck via a dielectric, and the focus ring is attracted and cooled. In addition to the power source for sample adsorption, it has a power source for focus ring adsorption, and the adsorption voltage is controlled by each of the sample and the focus ring.

  Patent Document 4 also describes a method of cooling the focus ring by directly adsorbing it to the electrostatic chuck. A plurality of heat transfer gas introduction grooves are formed on the upper surface of the outer periphery of the electrostatic chuck on which the focus ring is placed. The cooling efficiency of the focus ring is improved.

In Patent Document 4, a bias is applied to the focus ring itself by inserting a thick dielectric ring under the focus ring installed around the sample, and heat input from plasma to the focus ring is suppressed. Suppresses and keeps the focus ring temperature low.
As described above, various methods for cooling the focus ring have been considered.

JP-A-1-251735 JP-A-8-255783 JP 2005-64460 A JP 2007-258500 A

  An object of the present invention is to suppress the consumption of the focus ring by cooling the focus ring to a temperature equivalent to that of the sample with a simple structure, and to keep the etching characteristics of the outer periphery of the sample good for a long period of time.

  The vacuum processing apparatus of the present invention includes a vacuum processing chamber, a sample stage on which a sample is placed and having a coolant channel for controlling the temperature of the sample inside, and the sample is electrostatically adsorbed to the sample stage. An electrostatic adsorption power source, a first electrostatic adsorption layer for electrostatically adsorbing a sample on the surface of the sample table, a second electrostatic adsorption layer for electrostatically adsorbing a focus ring on the surface of the sample table, Means for supplying a heat transfer gas for controlling the temperature of the sample on the back of the sample, and a vacuum processing apparatus having heat transfer gas supply grooves on the surfaces of the first and second electrostatic adsorption layers, respectively. In order to supply the heat transfer gas supply means to the sample center side and the sample outer peripheral side at different pressures, the heat transfer gas supply means has two systems of heat transfer gas supply means, and the heat transfer gas supply path is branched to a focus ring mounting surface. Heat transfer gas for cooling is shared with heat transfer gas for wafer cooling And wherein the Rukoto.

  In the vacuum processing apparatus of the present invention, the heat transfer gas path branched to the focus ring mounting surface is branched from a path for supplying the heat transfer gas to the outer peripheral side of the sample.

  In the vacuum processing apparatus of the present invention, the heat transfer gas path branched to the focus ring mounting surface is branched from a path for supplying heat transfer gas to the center side of the sample. .

  In the vacuum processing apparatus of the present invention, the heat transfer gas path branched to the focus ring mounting surface supplies the heat transfer gas to the outer peripheral side of the sample and the heat transfer gas to the center side of the sample. It is characterized by branching from both sides of the route.

  The vacuum processing apparatus of the present invention further includes a heat transfer gas branch path that branches from the outer peripheral side of the sample to the focus ring mounting surface, and a heat transfer gas branch path from the center side of the sample to the focus ring mounting surface. Each of the heat transfer gas branch paths is provided with an open / close valve.

In the vacuum processing apparatus of the present invention, the volume resistivity of the first electrostatic adsorption layer is 10 ⁸ Ωcm to 10 ¹² Ωcm, and the volume resistivity of the second electrostatic adsorption layer is the first electrostatic adsorption layer. Similar to the volume resistivity of the electrostatic adsorption layer, it is 10 ⁸ Ωcm to 10 ¹² Ωcm.

  According to the present invention, the temperature of the focus ring can be cooled to the same level as that of the sample with a simple structure by branching the path of the heat transfer gas for cooling the sample to the focus ring, and the consumption of the focus ring is suppressed. As a result, the etching characteristics of the outer periphery of the sample can be kept good for a long period of time.

FIG. 1 is a sectional view of a vacuum processing apparatus according to an embodiment of the present invention. FIG. 2 is a detailed sectional view of the sample stage of the vacuum processing apparatus according to the first embodiment of the present invention. FIG. 3 is a detailed sectional view of the sample stage of the vacuum processing apparatus according to the second embodiment of the present invention. FIG. 4 is a detailed sectional view of the sample stage of the vacuum processing apparatus according to the third embodiment of the present invention.

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

  FIG. 1 shows a cross-sectional view of a vacuum processing apparatus according to Embodiment 1 of the present invention. The vacuum processing apparatus of the present invention includes a vacuum processing chamber 1, an exhaust duct 2, a sample stage 4 on which a sample 3 such as a semiconductor wafer is placed, an upper electrode 5 to which high-frequency power for plasma generation is supplied, and plasma generation High frequency power supply 6, high frequency bias power supply 7, electrostatic attraction DC power supply 8, solenoid coil 9, yoke 10, processing gas supply path 11, shower plate 12, matching box 13, and focus ring 14 And a susceptor 15, a first filter 16 and a second filter 17.

  A high frequency power source 6 for plasma generation is connected to the upper electrode 5 in the vacuum processing chamber 1 through a matching box 13 to supply high frequency energy. A high-frequency bias power source 7 is connected to the sample stage 4 via a first filter 16 and also serves as an electrode. Further, a DC power supply 8 for electrostatic adsorption is connected to the sample stage 4 via a second filter 17 and supplies electric power for electrostatically adsorbing the sample 3 to the sample stage 4.

  The upper electrode 5 and the sample stage 4 are installed facing each other, and are configured as a pair of electrodes. A shower plate 12 is installed below the upper electrode 5 and discharges the processing gas supplied from the processing gas supply path 11 into the vacuum processing chamber 1. The processing gas released into the vacuum processing chamber 1 is turned into plasma by the high frequency energy supplied to the upper electrode 5, and this plasma is controlled by controlling the magnetic field generated by the solenoid coil 9 and the yoke 10. Is homogenized within.

  A detailed sectional view of the sample stage 4 is shown in FIG. The sample stage 4 has a refrigerant flow path 18 through which a refrigerant flows, and controls the temperature of the sample 3. A temperature controller 19 is connected to the refrigerant channel 18, and the temperature of the sample stage 4 is controlled by circulating the refrigerant adjusted to a desired temperature from −20 ° C. to about 80 ° C. through the refrigerant channel 18. It is carried out.

  On the surface of the sample table 4, a first electrostatic adsorption layer 20 for electrostatically adsorbing the sample 3 to the sample table 4 and a focus ring on the focus ring mounting surface on the outer periphery of the sample mounting surface of the sample table 4 14 has a second electrostatic adsorption layer 21 for electrostatic adsorption.

The volume resistivity of the first electrostatic adsorption layer 20 is 10 ⁸ Ωcm to 10 ¹² Ωcm, and the sample 3 is electrostatically adsorbed to the sample stage 4 by the Johnson-Rahbek force. Further, in order to attract the focus ring 14 to the focus ring placement surface with the same suction force as that of attracting the sample 3 to the sample placement surface, the volume resistivity of the second electrostatic adsorption layer 21 is set to the first static force. The same 10 ⁸ Ωcm to 10 ¹² Ωcm as the volume resistivity of the electroadsorption layer 20 was used.

  The sample stage 4 has a center side heat transfer gas supply path 22 and an outer peripheral side heat transfer gas supply path 23 for supplying a heat transfer gas such as He gas to the back surface of the sample 3. In order to supply the heat transfer gas at different pressures on the outer peripheral side, two gas supply paths are provided. The heat transfer gas can be controlled by the heat transfer gas supply pressure control means 24 and the heat transfer gas supply pressure control means 25, and the sample 3 is cooled in proportion to the pressure of the heat transfer gas. Thus, temperature control can be performed on the center side and the outer peripheral side of the sample 3 so that the in-plane temperature distribution of the sample 3 becomes uniform.

  Of these two heat transfer gas supply paths, the outer peripheral heat transfer gas supply path 23 is branched to the mounting surface of the focus ring 14, and the heat transfer gas is shared between the outer peripheral side of the sample 3 and the focus ring 14. To do. The heat transfer gas pressure supplied from the heat transfer gas branch path 26 to the back surface of the focus ring 14 is substantially the same pressure as the heat transfer gas supplied to the outer periphery of the sample 3.

  The first electrostatic adsorption layer 20 has an annular heat transfer gas supply groove 27 on the center side of the sample and a heat transfer gas supply groove 28 on the outer periphery of the sample for spreading the heat transfer gas to the back surface of the sample 3. A plurality of concentric circles are provided. The sample 3 is placed in order to prevent the heat transfer gas supplied to the heat transfer gas supply groove 27 on the sample center side and the heat transfer gas supply groove 28 on the sample outer peripheral side from leaking from between the back surface of the sample 3 and the sample stage 4. An annular sealing surface is provided on the outermost periphery of the surface. In addition, since the heat transfer gas is supplied by two systems on the center side and the outer periphery side of the sample 3, a seal portion is provided so that the heat transfer gas on the center side and the outer periphery side do not communicate with each other, thereby dividing the pressure region of the heat transfer gas. ing.

  Similarly to the surface of the first electrostatic adsorption layer 20, the surface of the second electrostatic adsorption layer 21 is also provided with a heat transfer gas supply groove 29 on the focus ring mounting surface, and the width is about 1 mm to 5 mm. The depth is about 10 μm to 200 μm, and two are provided.

  By providing a plurality of grooves, the pressure of the heat transfer gas and the adsorption area of the focus ring 14 can be optimized, and the focus ring 14 can be efficiently cooled. Even if one heat transfer gas supply groove 29 on the focus ring mounting surface in the second electrostatic adsorption layer 21 has an effect of cooling the focus ring 14, the heat transfer gas leaks from the end of the focus ring 14. Therefore, the range in which the pressure on the back surface of the focus ring can maintain a desired pressure is narrowed.

  By providing a plurality of grooves, the range in which the pressure of the heat transfer gas can be maintained can be widened, and the focus ring 14 can be efficiently cooled. Therefore, two or more heat transfer gas supply grooves 29 on the focus ring mounting surface are provided. It is desirable.

  When two or more heat transfer gas supply grooves 29 on the focus ring mounting surface are provided, the width of the groove can be made narrower than when only one heat transfer gas supply groove 29 is provided on the focus ring mounting surface. . When the width of the heat transfer gas supply groove 29 on the focus ring mounting surface of the focus ring mounting portion is narrowed, the pressure loss when the heat transfer gas spreads into the heat transfer gas supply groove 29 of the focus ring mounting surface is reduced. By increasing the depth of the groove to make it smaller, it is possible to secure the flow rate of the gas flowing through the heat transfer gas supply groove 29 on the focus ring mounting surface.

  By using the configuration as described above, the temperature of the focus ring 14 can be cooled to the same temperature as that of the outer periphery of the sample 3, consumption of the focus ring 14 is reduced, and etching characteristics of the outer periphery of the sample 3 are reduced. It can be maintained well for a long time.

  A second embodiment of the present invention is shown in FIG. A duplicate description with the first embodiment is omitted. In the second embodiment, the heat transfer gas supply path 30 to the focus ring mounting portion that branches the heat transfer gas to the focus ring 14 is provided on the center side heat transfer gas supply path 22 on the center side of the sample 3. The heat transfer gas supplied to the center side of the sample 3 is shared with the focus ring 14. At this time, since the focus ring 14 has the same heat transfer gas pressure as the center side of the sample 3, a cooling effect equivalent to the center side of the sample 3 is obtained.

  A third embodiment of the present invention is shown in FIG. A duplicate description with the first embodiment is omitted. In the third embodiment, the center side heat transfer gas supply path 22 of the sample 3 has a heat transfer gas branch path 31 from the sample center side branched to the focus ring 14 to the focus ring mounting surface, and further the sample. The outer peripheral heat transfer gas supply path 23 on the outer peripheral side 3 also has a heat transfer gas branch path 32 from the sample outer peripheral side branched to the focus ring 14 to the focus ring mounting surface.

  The heat transfer gas branch path 31 from the sample center side branched from the center side heat transfer gas supply path 22 of the sample 3 to the focus ring 14 to the focus ring mounting surface has an open / close valve 33. Can be done automatically. Further, the heat transfer gas branch path 32 branched from the outer periphery side heat transfer gas supply path 23 of the sample 3 to the focus ring 14 from the outer periphery side of the sample to the focus ring mounting surface also has an open / close valve 34. Opening and closing can also be performed automatically.

  When it is desired to set the temperature of the focus ring 14 to the same temperature as the center side of the sample 3, the open / close valve 33 on the heat transfer gas branch path 31 from the sample center side to the focus ring mounting surface is opened to transfer to the focus ring 14. Supply hot gas. Since the heat transfer gas pressure on the back surface of the focus ring 14 is equivalent to the heat transfer gas pressure on the center side of the sample 3, a cooling effect equivalent to that on the center side of the sample 3 is obtained.

  When the temperature of the focus ring 14 is desired to be the same temperature as the outer peripheral side of the sample 3, the open / close valve 34 on the heat transfer gas branch path 32 from the outer peripheral side of the sample to the focus ring mounting surface is opened, and the center side of the sample is opened. The on-off valve 33 on the heat transfer gas branch path 31 from the center to the focus ring mounting surface is closed. Since the heat transfer gas pressure on the back surface of the focus ring 14 is equivalent to the heat transfer gas pressure on the outer peripheral side of the sample 3, a cooling effect equivalent to that on the outer peripheral side of the sample 3 is obtained.

  Further, the opening / closing valve 33 and the opening / closing valve 34 are provided with a heat transfer gas flow rate adjusting function so that the flow rate of the heat transfer gas in the heat transfer gas branch path 32 from the outer periphery of the sample to the focus ring mounting surface and the center of the sample. By adjusting the ratio of the heat transfer gas flow rate of the heat transfer gas branch path 31 from the side to the focus ring mounting surface, the heat transfer gas pressure on the back surface of the focus ring 14 is changed between the center side and the outer periphery side of the sample 3. By setting the hot gas pressure, an intermediate cooling effect between the center side and the outer peripheral side of the sample 3 can be obtained.

  The cooling capacity of the focus ring 14 can be changed by controlling the opening / closing of the opening / closing valve 33 on the center side and the opening / closing valve 34 on the outer periphery side using the configuration as described above.

DESCRIPTION OF SYMBOLS 1 Vacuum processing chamber 2 Exhaust duct 3 Sample 4 Sample stand 5 Upper electrode 6 High frequency power supply for plasma generation 7 High frequency bias power supply 8 DC power supply for electrostatic adsorption 9 Solenoid coil 10 Yoke 11 Processing gas supply path 12 Shower plate 13 Matching box 14 Focus Ring 15 Susceptor 16 First filter 17 Second filter 18 Refrigerant flow path 19 Temperature controller 20 First electrostatic adsorption layer 21 Second electrostatic adsorption layer 22 Center side heat transfer gas supply path 23 Outer circumference side heat transfer Gas supply path 24 Heat transfer gas supply pressure control means 25 Heat transfer gas supply pressure control means 26 Heat transfer gas branch path 27 Heat transfer gas supply groove on the sample center side 28 Heat transfer gas supply groove on the sample outer peripheral side 29 Focus ring mounting Heat transfer gas supply groove on the surface 30 Heat transfer gas supply path to the focus ring mounting surface 31 Heat transfer gas branch path from the sample outer periphery side to the focus ring placement surface 33 Open / close valve 34 Open / close valve

Claims (6)

A vacuum processing chamber; a sample stage on which a sample is placed and having a coolant channel for controlling the temperature of the sample; an electrostatic adsorption power source for electrostatically adsorbing the sample and the focus ring to the sample stage; A first electrostatic adsorption layer for electrostatically adsorbing the sample on the surface of the sample stage; a second electrostatic adsorption layer for electrostatically adsorbing the focus ring on the surface of the sample stage; and the sample Means for supplying a heat transfer gas for controlling the temperature of the sample on the back surface, and a vacuum processing apparatus having heat transfer gas supply grooves on the surfaces of the first and second electrostatic adsorption layers, respectively.
The heat transfer gas supply means has two systems of heat transfer gas supply means for supplying the heat transfer gas supply means to the center side of the sample and the outer peripheral side of the sample at different pressures, and the heat transfer gas supply path is provided on the focus ring mounting surface. A vacuum processing apparatus that branches into a heat transfer gas supply groove and shares the heat transfer gas for cooling the focus ring with the heat transfer gas for cooling the sample.   2. The vacuum processing apparatus according to claim 1, wherein a heat transfer gas path branched to a heat transfer gas supply groove on the focus ring mounting surface is branched from a path for supplying a heat transfer gas to the outer peripheral side of the sample. A vacuum processing apparatus.   2. The vacuum processing apparatus according to claim 1, wherein a heat transfer gas path branched to a heat transfer gas supply groove on the focus ring mounting surface is branched from a path supplying a heat transfer gas to the center side of the sample. A vacuum processing apparatus.   2. The vacuum processing apparatus according to claim 1, wherein a heat transfer gas path branched into a heat transfer gas supply groove on the focus ring mounting surface is provided on a path for supplying a heat transfer gas to an outer peripheral side of the sample and a center side of the sample. A vacuum processing apparatus, which is branched from both paths for supplying heat transfer gas.   5. The vacuum processing apparatus according to claim 4, wherein a heat transfer gas branch path branches from an outer peripheral side of the sample to a heat transfer gas supply groove of the focus ring mounting surface, and the focus ring mounting surface from the center side of the sample. A vacuum processing apparatus comprising an open / close valve in each heat transfer gas branch path of the heat transfer gas branch path to the heat transfer gas supply groove. 6. The vacuum processing apparatus according to claim 1, wherein the first electrostatic adsorption layer has a volume resistivity of 10 ⁸ Ωcm to 10 ¹² Ωcm, and the second electrostatic adsorption layer. The vacuum processing apparatus is characterized in that the volume resistivity is 10 ⁸ Ωcm to 10 ¹² Ωcm, similarly to the volume resistivity of the first electrostatic adsorption layer.

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