Helium supply device and method for an electrostatic chuck

Abstract

The present invention relates to a helium supply device and method for an electrostatic chuck. The helium supply device includes a bottom plate, on which a helium inlet pipeline and a helium outlet pipeline are fixedly arranged. The helium inlet pipeline and the helium outlet pipeline are connected through a mass flow controller. The helium outlet pipeline includes an electrostatic chuck purge pipeline and a pumping unit pipeline arranged in parallel. The helium inlet pipeline includes a pressure regulating valve, an electronic pressure gauge, and a first pneumatic valve arranged in sequence along the inlet direction. A second pneumatic valve is arranged on the electrostatic chuck purge pipeline, and a third pneumatic valve is arranged on the pumping unit pipeline. The present invention can intuitively and effectively achieve uniform heat purge and temperature control of the bottom of the electrostatic chuck in a pneumatic and electric control manner.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor etching equipment, and particularly relates to a helium supply device and method for an electrostatic chuck. Background Art

[0002] In semiconductor etching equipment, the temperature control of the electrostatic chuck is particularly important, and the change of its temperature directly affects the process uniformity and effect of the wafer. In the industry, helium is often used to purge the bottom of the electrostatic chuck, and the constant-temperature helium enables it to achieve the effect of cooling or heat distribution.

[0003] CN104465451A discloses an electrostatic chuck and its gas supply method. The electrostatic chuck located at the bottom of the vacuum processing chamber has a diameter equal to or larger than the diameter of the substrate fixed and supported by the electrostatic chuck; the second process gas is transported to the edge position on the back of the substrate through the gas channel located at the edge of the electrostatic chuck, and helium or the second process gas is transported to the center position on the surface of the substrate through the gas channel located at the center of the electrostatic chuck for heat transfer cooling. Since the composition of the second process gas is the same as or very close to the composition of the first process gas transported to the surface of the substrate for reaction treatment, it can ensure that the gas after mixing the second process gas and the first process gas will not change the reaction conditions when processing the edge of the substrate. The gas supply method provided by this invention can be applied to larger-sized electrostatic chucks to obtain better temperature distribution effects on the substrate.

[0004] CN113725141A discloses a porous ceramic electrostatic chuck, including a chuck body, and a plurality of regularly distributed and vertically penetrating helium holes are provided on the chuck body, and each of the helium holes is communicated through a groove group arranged on the upper surface of the chuck body and in a closed-loop structure. This invention has the characteristics of uniform and comprehensive distribution of helium holes and uniform distribution of helium, ensuring the temperature distribution uniformity on the surface of the electrostatic chuck.

[0005] CN107818940A discloses an electrostatic chuck device and its temperature control method. The electrostatic chuck device includes an electrostatic chuck disposed in a process chamber; a cold source supply pipe disposed in the base of the electrostatic chuck device, with its cooling end guiding to the back of the wafer and its cold supply end communicating with an external cooling gas source; a pressure control unit for controlling the working pressure of the cold source introduced to the back of the wafer; a temperature control unit disposed on the cold source supply pipe for controlling the temperature of the cooling end of the cold source supply pipe; and an exhaust device communicating with the external cooling gas source.

[0006] In order to achieve the purpose of uniform temperature distribution of the electrostatic chuck, the above-mentioned inventions have improved the body structure or external equipment of the electrostatic chuck, but there is still room for further improvement in aspects such as ensuring stable helium supply and controllable temperature purging.

[0007] Therefore, in view of the deficiencies of the prior art, there is an urgent need to provide a device that can achieve uniform heat purging and temperature control of an electrostatic chuck and stable and controllable helium supply. Summary of the Invention

[0008] The purpose of the present invention is to provide a helium supply device and method for an electrostatic chuck, which realizes uniform heat purging and temperature control of the electrostatic chuck and stable and controllable helium supply.

[0009] To achieve the purpose of this invention, the following technical solutions are adopted:

[0010] In a first aspect, the present invention provides a helium supply device for an electrostatic chuck. The helium supply device includes a bottom plate, on which a helium inlet pipeline and a helium outlet pipeline are fixedly arranged. The helium inlet pipeline and the helium outlet pipeline are connected through a mass flow controller. The helium outlet pipeline includes an electrostatic chuck purging pipeline and a pumping unit pipeline arranged in parallel; the helium inlet pipeline includes a pressure regulating valve, an electronic pressure gauge, and a first pneumatic valve arranged in sequence along the inlet direction; a second pneumatic valve is arranged on the electrostatic chuck purging pipeline, and a third pneumatic valve is arranged on the pumping unit pipeline.

[0011] The helium supply device for an electrostatic chuck provided by the present invention can visually and effectively perform uniform heat purging and temperature control on the bottom of the electrostatic chuck in a pneumatic and electric control manner; when helium is introduced into the electrostatic chuck, the stable and constant flow pressure enables the wafer on the electrostatic chuck to be in the best micro-suspension state. At the same time, the introduction of helium can stabilize the pressure in the cavity where the electrostatic chuck is located and maintain process stability; since the temperature of helium is constant, the temperature of the electrostatic chuck can be kept uniform, so that the wafer is also in a constant temperature state during the process, effectively improving the process effect.

[0012] Preferably, a manual valve is arranged on the pipeline before the pressure regulating valve.

[0013] The manual valve is provided to manually quickly close the pipeline manually in case of an emergency or when there is a problem with the electro-pneumatic valve, so as to minimize damage at the fastest speed.

[0014] Preferably, a filter is arranged on the pipeline before the manual valve.

[0015] The filter can filter out impurities and fine particles in the helium.

[0016] Preferably, the outlet of the electrostatic chuck purging pipeline is connected to the bottom of the electrostatic chuck.

[0017] The outlet of the pumping unit pipeline is connected to a vacuum pipeline. One end of the vacuum pipeline is connected to the cavity where the electrostatic chuck is located, and the other end is connected to the pumping unit.

[0018] Preferably, a sensor is disposed in the cavity where the electrostatic chuck is located.

[0019] Preferably, the material of the bottom plate includes stainless steel.

[0020] The setting of the sensor can detect whether a wafer is placed on the electrostatic chuck, so as to judge whether the helium supply process is carried out; adding a sensor can also view and control the entire system through the host computer at any time, so as to modularly control the helium supply device.

[0021] In a second aspect, the present invention provides a helium supply method for an electrostatic chuck. The helium supply method is carried out by the helium supply device for an electrostatic chuck described in the first aspect. The helium supply method includes the following steps:

[0022] Helium flows through the pressure regulating valve and the first pneumatic valve in sequence and then enters the mass pressure controller. After pressure regulation, it flows through the second pneumatic valve and then is introduced into the electrostatic chuck for purging; the first pneumatic valve and the second pneumatic valve are in an interlocking relationship. When the following conditions are met, the first pneumatic valve and the second pneumatic valve are opened simultaneously: (1) the pressure in the cavity where the electrostatic chuck is located ≤ 20 Torr; (2) a wafer is placed on the electrostatic chuck; (3) the initial inlet pressure of helium is 9 - 11 PSI; when no wafer is placed on the electrostatic chuck, the first pneumatic valve and the second pneumatic valve are in a closed state, and the third pneumatic valve is opened to evacuate the gas in the pumping unit pipeline.

[0023] The helium supply method for the electrostatic chuck provided by the present invention, through setting the interlock of the first pneumatic valve and the second pneumatic valve and the pressure control of the mass pressure controller, makes the gas inflow and outflow objective and effective at any time during the process; by setting three-layer precondition conditions, the reliability of the entire system can be effectively protected, and the mass pressure controller can be protected from damage.

[0024] The pressure in the cavity where the electrostatic chuck is located ≤ 20 Torr. For example, it can be 20 Torr, 18 Torr, 16 Torr, 15 Torr or 13 Torr, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0025] The initial inlet pressure of helium is 9 - 11 PSI. For example, it can be 9 PSI, 9.5 PSI, 10 PSI, 10.5 PSI or 11 PSI, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0026] Preferably, the pressure in the cavity where the electrostatic chuck is located is controlled by a pumping unit connected through a pumping unit pipeline.

[0027] Before the helium supply process, the pumping pump group composed of fore-pump bodies such as dry pumps and molecular pumps needs to evacuate the cavity where the electrostatic chuck is located to meet the basic pressure of the process at the fastest speed.

[0028] Preferably, the detection of whether a wafer is placed on the electrostatic chuck or not is carried out by a sensor arranged in the cavity where the electrostatic chuck is located.

[0029] Preferably, the initial inlet pressure of the helium is controlled by a pressure regulating valve and the reading is carried out by an electronic pressure gauge.

[0030] The pressure range after entering the mass pressure controller and being regulated ≤ 100 Torr. For example, it can be 100 Torr, 80 Torr, 50 Torr, 20 Torr or 10 Torr, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0031] The temperature of the helium purged into the electrostatic chuck is 20 - 30 °C. For example, it can be 20 °C, 22 °C, 25 °C, 28 °C or 30 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0032] When the helium enters the helium supply device, the pressure at the facility end cannot be controlled. Excessive pressure will damage the mass pressure controller and cause inaccurate readings. Therefore, a pressure control valve is adopted. The reading of the electronic pressure gauge is read through the upper computer, and the inlet pressure is manually adjusted to meet the inlet protection requirements.

[0033] When helium is introduced into the electrostatic chuck, a stable and constant flow pressure makes the wafer on the electrostatic chuck in the best micro-suspension state. Excessive gas will blow up the wafer, causing a risk of damage, while too little helium cannot blow the electrostatic chuck. Therefore, the pressure needs to be regulated within a reasonable range.

[0034] The temperature of the purged helium is kept constant, which can keep the electrostatic chuck in a uniform heat state, and further make the wafer in a constant temperature state during the process, thus effectively improving the process effect.

[0035] Preferably, the helium is filtered before flowing through the pressure regulating valve.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The helium supply device of the electrostatic chuck provided by the present invention can visually and effectively perform uniform heat blowing and temperature control on the bottom of the electrostatic chuck in a pneumatic and electric control manner; when helium is introduced into the electrostatic chuck, the stable and constant flow pressure enables the wafer on the electrostatic chuck to be in the best micro-suspension state. At the same time, the introduction of helium can stabilize the pressure in the cavity where the electrostatic chuck is located and maintain process stability; since the temperature of helium is constant, the temperature of the electrostatic chuck can be kept uniform, so that the wafer is also in a constant temperature state during the process, effectively improving the process effect.

[0038] (2) The helium supply method of the electrostatic chuck provided by the present invention enables the gas to flow in and out objectively and effectively at any time during the process through the interlocking of the first pneumatic valve and the second pneumatic valve and the pressure control of the mass pressure controller; by setting manual valves and three-layer pre-stage conditions, the reliability of the entire system can be effectively protected, and the mass pressure controller can be protected from damage; by adding sensors and electronic pressure gauges, the entire system can be viewed and controlled at any time through the upper computer, thereby modularly controlling the helium supply device. Description of the Drawings

[0039] Figure 1 is a schematic structural diagram of the helium supply device of the electrostatic chuck provided in Embodiment 1 of the present invention;

[0040] Figure 2 is a schematic connection diagram of the helium supply device of the electrostatic chuck provided in Embodiment 1 of the present invention.

[0041] Wherein: 1, bottom plate; 2, helium inlet pipeline; 3, mass pressure controller; 4, electrostatic chuck purge pipeline; 5, pumping unit pipeline; 6, filter; 7, manual valve; 8, pressure regulating valve; 9, electronic pressure gauge; 10, first pneumatic valve; 11, second pneumatic valve; 12, third pneumatic valve; 13, vacuum pumping pipeline; 14, sensor. Detailed Embodiments

[0042] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0043] Embodiment 1

[0044] This embodiment provides a helium supply device for an electrostatic chuck, and the schematic structural diagram is as Figure 1 shown, and the schematic connection diagram is as Figure 2As shown, the helium supply device includes a bottom plate 1, on which a helium inlet pipeline 2 and a helium outlet pipeline are fixedly arranged. The helium inlet pipeline 2 and the helium outlet pipeline are connected by a mass pressure controller 3. The helium outlet pipeline includes an electrostatic chuck purging pipeline 4 and a pumping unit pipeline 5 arranged in parallel. The helium inlet pipeline 2 includes a filter 6, a manual valve 7, a pressure regulating valve 8, an electronic pressure gauge 9, and a first pneumatic valve 10 arranged in sequence along the inlet direction. A second pneumatic valve 11 is arranged on the electrostatic chuck purging pipeline 4, and a third pneumatic valve 12 is arranged on the pumping unit pipeline 5. The outlet of the electrostatic chuck purging pipeline 4 is connected to the bottom of the electrostatic chuck. The outlet of the pumping unit pipeline 5 is connected to a vacuum pumping pipeline 13. One end of the vacuum pumping pipeline 13 is connected to the cavity where the electrostatic chuck is located, and the other end is connected to the pumping unit. A sensor 14 is arranged in the cavity where the electrostatic chuck is located.

[0045] The method for supplying helium to the electrostatic chuck using the helium supply device includes the following steps:

[0046] When no wafer is placed on the electrostatic chuck, the first pneumatic valve 10 and the second pneumatic valve 11 are in the closed state, and the third pneumatic valve 12 is opened to evacuate the gas in the pumping unit pipeline 5. The first pneumatic valve 10 and the second pneumatic valve 11 are in an interlock relationship. When the pumping unit controls the pressure in the cavity where the electrostatic chuck is located to be 20 Torr, a wafer is detected on the electrostatic chuck through the sensor 14, and the pressure regulating valve 8 controls the initial inlet pressure of helium so that the reading of the electronic pressure gauge 9 is 10 PSI, the first pneumatic valve 10 and the second pneumatic valve 11 are opened simultaneously. At this time, the helium passes through the filter treatment and then flows through the pressure regulating valve 8 and the first pneumatic valve 10 in sequence, and then enters the mass pressure controller 3. After the pressure is regulated to 20 Torr, it flows through the second pneumatic valve 11 and then is introduced into the electrostatic chuck for purging. The temperature of the helium is 20 °C.

[0047] In this embodiment, the supplied helium has stable flow pressure and temperature, which can make the wafer on the electrostatic chuck in the best micro-suspension state and constant temperature state, effectively improving the process effect.

[0048] Embodiment 2

[0049] This embodiment provides a helium supply device for an electrostatic chuck. The difference from Embodiment 1 is that the helium inlet pipeline 2 is not provided with a manual valve 7, and the rest are the same as in Embodiment 1.

[0050] In this embodiment, no manual valve is provided. In case of an emergency or when the electro-pneumatic valve has a problem, the pipeline cannot be closed, thus increasing the risk of pipeline damage.

[0051] Embodiment 3

[0052] This embodiment provides a helium supply device for an electrostatic chuck. The difference from Embodiment 1 is that the helium inlet pipeline 2 is not provided with a sensor 14, and the rest are the same as in Embodiment 1.

[0053] In this embodiment, no sensor is provided, so it is impossible to automatically and real-time detect whether a wafer is placed on the electrostatic chuck. Furthermore, it is difficult to meet the condition of simultaneously opening the first pneumatic valve and the second pneumatic valve, and it is impossible to modularly control the helium supply device.

[0054] Comparative Example 1

[0055] This comparative example provides a helium supply device for an electrostatic chuck. The difference between the method of using the helium supply device to supply helium to the electrostatic chuck and that in Embodiment 1 is that when no wafer is placed on the electrostatic chuck, the third pneumatic valve 12 is not opened to evacuate the gas in the pumping unit pipeline 5, and the rest are the same as in Embodiment 1.

[0056] In this comparative example, no gas evacuation treatment is performed. During the process, helium will flush air into the process chamber, thereby causing pollution.

[0057] Comparative Example 2

[0058] This comparative example provides a helium supply device for an electrostatic chuck. The difference between the method of using the helium supply device to supply helium to the electrostatic chuck and that in Embodiment 1 is that the first pneumatic valve 10 and the second pneumatic valve 11 are not in an interlock relationship, and no three-layer precondition is set, and the rest are the same as in Embodiment 1.

[0059] In this comparative example, no interlock relationship between the first pneumatic valve and the second pneumatic valve is established and no three-layer precondition is set, so it is impossible to objectively and effectively control the inflow and outflow of gas at any time, and the reliability of the entire system cannot be protected.

[0060] In summary, the helium supply device for the electrostatic chuck provided by the present invention can intuitively and effectively perform uniform heat purging and temperature control on the bottom of the electrostatic chuck in terms of pneumatic and electric control methods; when helium is introduced into the electrostatic chuck, the stable and constant flow pressure enables the wafer on the electrostatic chuck to be in the best micro-suspension state. At the same time, the introduction of helium can stabilize the pressure in the chamber where the electrostatic chuck is located and maintain process stability; since the temperature of helium is constant, the temperature of the electrostatic chuck can be kept uniform, so that the wafer is also in a constant temperature state during the process, effectively improving the process effect.

[0061] The helium gas supply method of the electrostatic chuck provided by the present invention interlocks the first pneumatic valve and the second pneumatic valve, and controls the pressure of the mass pressure controller, so that during the process, the inflow and outflow of gas are objectively and effectively at any time; by setting manual valves and three-layer pre-stage conditions, the reliability of the entire system can be effectively protected, and the mass pressure controller can be protected from damage; by adding sensors and electronic pressure gauges, the entire system can be viewed and controlled at any time through the upper computer, so as to modularly control the helium gas supply device.

[0062] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A helium supply method for an electrostatic chuck, characterized in that, The helium supply method includes the following steps: Helium flows through a pressure regulating valve and a first pneumatic valve in sequence and then enters a mass pressure controller. After pressure regulation, it flows through a second pneumatic valve and then is introduced into an electrostatic chuck for purging; The first pneumatic valve and the second pneumatic valve are in an interlocking relationship. When the following conditions are met, the first pneumatic valve and the second pneumatic valve are opened simultaneously: (1) The pressure in the cavity where the electrostatic chuck is located ≤ 20 Torr; (2) A wafer is placed on the electrostatic chuck; (3) The initial inlet pressure of helium is 9 - 11 PSI; When no wafer is placed on the electrostatic chuck, the first pneumatic valve and the second pneumatic valve are in a closed state, and the third pneumatic valve is opened to evacuate the gas in the pipeline of the pumping unit; The helium supply method is carried out through a helium supply device of the electrostatic chuck. The helium supply device includes a bottom plate, on which a helium inlet pipeline and a helium outlet pipeline are fixedly arranged. The helium inlet pipeline and the helium outlet pipeline are connected through a mass pressure controller. The helium outlet pipeline includes an electrostatic chuck purging pipeline and a pumping unit pipeline arranged in parallel; The helium inlet pipeline includes a pressure regulating valve, an electronic pressure gauge, and a first pneumatic valve arranged in sequence along the inlet direction; A second pneumatic valve is arranged on the electrostatic chuck purging pipeline, and a third pneumatic valve is arranged on the pumping unit pipeline; The outlet of the pumping unit pipeline is connected to a vacuum pipeline. One end of the vacuum pipeline is connected to the cavity where the electrostatic chuck is located, and the other end is connected to the pumping unit.

2. The helium gas supply method according to claim 1, wherein A manual valve is arranged on the pipeline before the pressure regulating valve.

3. The helium supply method according to claim 2, characterized in that, A filter is arranged on the pipeline before the manual valve.

4. The helium supply method according to claim 1, wherein The outlet of the electrostatic chuck purging pipeline is connected to the bottom of the electrostatic chuck.

5. The helium gas supply method according to claim 1, wherein A sensor is arranged in the cavity where the electrostatic chuck is located.

6. The helium gas supply method according to claim 1, wherein, The pressure in the cavity where the electrostatic chuck is located is controlled by a pumping unit connected through the pumping unit pipeline.

7. The helium supply method according to claim 1, wherein The detection of whether a wafer is placed on the electrostatic chuck or not is carried out through a sensor arranged in the cavity where the electrostatic chuck is located.

8. The helium gas supply method according to claim 1, wherein The initial inlet pressure of helium is controlled by the pressure regulating valve and the reading is carried out through the electronic pressure gauge; The pressure range after adjustment after entering the mass pressure controller ≤ 100 Torr; The temperature of the helium introduced into the electrostatic chuck for purging is 20 - 30 °C.

9. The helium gas supply method according to claim 1, characterized in that, The helium is filtered before flowing through the pressure regulating valve.

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