Helium supply device and method for electrostatic chuck

Abstract

The invention relates to a helium supply device and method for an electrostatic chuck, the helium supply device comprises a bottom plate, a helium inlet pipeline and a helium outlet pipeline are fixedly arranged on the bottom plate, and the helium inlet pipeline and the helium outlet pipeline are connected through a mass pressure controller; the helium outlet pipeline comprises an electrostatic chuck purging pipeline and a sucking pump group pipeline which are arranged in parallel; the helium gas inlet pipeline comprises a pressure regulating valve, an electronic pressure gauge and a first pneumatic valve which are sequentially arranged along the gas inlet direction; a second pneumatic valve is arranged on the electrostatic chuck purging pipeline, and a third pneumatic valve is arranged on the sucking pump set pipeline. Uniform heat purging and temperature control on the bottom of the electrostatic chuck can be intuitively and effectively realized in pneumatic and electric control modes.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor etching equipment, and in particular 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 its temperature change directly affects the process uniformity and effect of the wafer. The industry often uses helium to purge the bottom of the electrostatic chuck, and the constant temperature helium can achieve the effect of cooling or evenly distributing heat.

[0003] CN104465451A discloses an electrostatic chuck and a gas supply method thereof, wherein the electrostatic chuck is located at the bottom of the vacuum processing chamber, and its diameter is equal to or greater than the diameter of the substrate fixedly supported by the electrostatic chuck; the second process gas is transported to the edge position of the back of the substrate by using the gas channel located at the edge of the electrostatic chuck, and the helium or the second process gas is transported to the center position of the substrate surface by using 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 substrate surface for reaction treatment, it can be ensured that the gas after the second process gas is mixed with the first process gas will not change the reaction conditions when processing the edge of the substrate. The gas supply method provided by the invention can be applied to electrostatic chucks of larger sizes to obtain a better temperature distribution effect on the substrate.

[0004] CN113725141A discloses a porous ceramic electrostatic chuck, comprising a chuck body, on which a number of regularly distributed helium holes are provided, each of which is connected by a groove group provided on the upper surface of the chuck body and in a closed loop structure. The invention has the characteristics of uniform and comprehensive distribution of helium holes and uniform distribution of helium, ensuring uniform temperature distribution on the surface of the electrostatic chuck, etc.

[0005] CN107818940A discloses an electrostatic chuck device and a temperature control method thereof. The electrostatic chuck device comprises an electrostatic chuck arranged in a process chamber; a cold source supply pipeline arranged in a base of the electrostatic chuck device, the cooling end of which leads to the back of a wafer, and the cold supply end of which is connected to 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 arranged on the cold source supply pipeline for controlling the temperature of the cooling end of the cold source supply pipeline; and an exhaust device connected to an external cooling gas source.

[0006] In order to achieve the purpose of uniform temperature distribution of the electrostatic chuck, the above invention improves the main structure or external equipment of the electrostatic chuck, but further improvements are needed in ensuring stable helium gas and temperature-controllable purging.

[0007] Therefore, in view of the shortcomings of the existing technology, it is urgently necessary to provide a device that can achieve uniform heat purging and temperature control of the electrostatic chuck and stable and controllable supply of helium. Summary of the invention

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

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a helium supply device for an electrostatic chuck, the helium supply device comprising a base 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 comprises an electrostatic chuck purge pipeline and a vacuum pump group pipeline arranged in parallel; the helium inlet pipeline comprises 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 vacuum pump group pipeline.

[0011] The helium supply device for the electrostatic chuck provided by the present invention can intuitively and effectively perform uniform heat blowing and temperature control on the bottom of the electrostatic chuck in a pneumatic and electrically controlled manner; when helium is introduced into the electrostatic chuck, a stable and constant flow pressure enables the wafer on the electrostatic chuck to be in an optimal micro-suspension state, and at the same time, the introduction of helium can stabilize the pressure in the cavity where the electrostatic chuck is located, thereby maintaining process stability; since the temperature of the 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, thereby effectively improving the process effect.

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

[0013] The manual valve is provided so that in case of emergency or when a problem occurs with the electric-controlled pneumatic valve, the pipeline can be quickly closed manually to reduce damage as quickly as possible.

[0014] Preferably, a filter is provided 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 purge pipeline is connected to the bottom of the electrostatic chuck.

[0017] The outlet of the vacuum pump group pipeline is connected to a vacuum pipe, one end of the vacuum pipe is connected to the cavity where the electrostatic suction cup is located, and the other end is connected to the vacuum pump group.

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

[0019] Preferably, the base plate is made of stainless steel.

[0020] The sensor can detect whether a wafer is placed on the electrostatic chuck, thereby determining whether the helium supply process is in progress; adding the sensor can also allow the host computer to check and control the entire system at any time, thereby modularly controlling 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 being performed by the helium supply device for the electrostatic chuck according to the first aspect, the helium supply method comprising 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 enters the electrostatic chuck for purging. The first pneumatic valve and the second pneumatic valve are interlocked. When the following conditions are met, the first pneumatic valve and the second pneumatic valve are opened at the same time: (1) the pressure in the cavity where the electrostatic chuck is located is ≤20Torr; (2) a wafer is placed on the electrostatic chuck; (3) the initial helium inlet pressure is 9-11PSI; when no wafer is placed on the electrostatic chuck, the first pneumatic valve and the second pneumatic valve are closed, and the third pneumatic valve is opened to evacuate the gas in the pipeline of the vacuum pump group.

[0023] The helium supply method for 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 the gas inflow and outflow are objective and effective at any time during the process; by setting three layers of front-stage 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 is ≤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 values ​​not listed within the numerical range are also applicable.

[0025] The initial helium inlet pressure is 9-11 PSI, for example, 9 PSI, 9.5 PSI, 10 PSI, 10.5 PSI or 11 PSI, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the pressure in the cavity where the electrostatic chuck is located is controlled by a vacuum pump group connected by a vacuum pump group pipeline.

[0027] Before the helium supply process is carried out, the vacuum pump group composed of the dry pump, molecular pump and other front-stage pump bodies needs to evacuate the cavity where the electrostatic chuck is located to meet the basic process pressure as quickly as possible.

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

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

[0030] The range of the pressure adjustment after entering the mass pressure controller is ≤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, and other values ​​not listed in the numerical range are also applicable.

[0031] The temperature of the helium gas introduced into the electrostatic chuck for purging is 20-30°C, for example, 20°C, 22°C, 25°C, 28°C or 30°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] When the helium enters the helium supply device, the pressure at the field service end cannot be controlled. Excessive pressure will damage the quality pressure controller and cause inaccurate readings. Therefore, a pressure control valve is used to read the reading of the electronic pressure gauge through the host computer, and the intake pressure is manually adjusted to meet the intake protection requirements.

[0033] When helium is passed into the electrostatic chuck, the stable and constant flow pressure keeps the wafer on the electrostatic chuck in the best micro-suspension state. Excessive gas will blow up the wafer, causing damage risk, while too little helium will not be able to blow the electrostatic chuck, so 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, thereby effectively improving the process effect.

[0035] Preferably, the helium gas is filtered before passing 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 for the electrostatic chuck provided by the present invention can intuitively and effectively perform uniform heat blowing and temperature control on the bottom of the electrostatic chuck in a pneumatic and electrically controlled manner; when helium is introduced into the electrostatic chuck, the stable and constant flow pressure makes the wafer on the electrostatic chuck in an optimal micro-suspension state. At the same time, the introduction of helium can stabilize the pressure in the cavity where the electrostatic chuck is located, thereby maintaining process stability; since the temperature of the 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, thereby effectively improving the process effect.

[0038] (2) The helium supply method for the electrostatic suction cup provided by the present invention, by setting the interlocking 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 the manual valve and the three-layer front-stage conditions, the reliability of the whole system can be effectively protected and the mass pressure controller can be protected from damage; by adding sensors and electronic pressure gauges, the whole system can be checked and controlled at any time by the host computer, thereby modularly controlling the helium supply device. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0041] Among them: 1, base plate; 2, helium inlet pipeline; 3, mass pressure controller; 4, electrostatic suction cup purge pipeline; 5, vacuum pump group 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 pipeline; 14, sensor. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0043] Example 1

[0044] This embodiment provides a helium supply device for an electrostatic chuck, the structural diagram of which is shown in FIG. Figure 1 As shown, the connection diagram is as follows Figure 2As shown, the helium supply device includes a base 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 through a mass pressure controller 3, and the helium outlet pipeline includes an electrostatic chuck purge pipeline 4 and an air pump group 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 air inlet direction; a second pneumatic valve 11 is arranged on the electrostatic chuck purge pipeline 4, and a third pneumatic valve 12 is arranged on the air pump group pipeline 5; the outlet of the electrostatic chuck purge pipeline 4 is connected to the bottom of the electrostatic chuck; the outlet of the air pump group pipeline 5 is connected to a vacuum pipeline 13, one end of the vacuum pipeline 13 is connected to the cavity where the electrostatic chuck is located, and the other end is connected to the air pump group; a sensor 14 is arranged in the cavity where the electrostatic chuck is located.

[0045] The method of supplying helium to an electrostatic chuck using the helium supply device comprises 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 a closed state, and the third pneumatic valve 12 is opened to evacuate the gas in the vacuum pump group pipeline 5; the first pneumatic valve 10 and the second pneumatic valve 11 are in an interlocking relationship. When the vacuum pump group controls the pressure in the cavity where the electrostatic chuck is located to be 20 Torr, the sensor 14 detects that a wafer is placed on the electrostatic chuck, and the pressure regulating valve 8 controls the initial helium intake pressure so that the electronic pressure gauge 9 reads 10PSI, the first pneumatic valve 10 and the second pneumatic valve 11 are opened at the same time. At this time, the helium flows through the pressure regulating valve 8 and the first pneumatic valve 10 in turn after being filtered, and then enters the mass pressure controller 3. After the pressure is adjusted to 20 Torr, it flows through the second pneumatic valve 11, and then passes into the electrostatic chuck for purging. The helium temperature is 20°C.

[0047] The helium gas introduced in this embodiment has a stable flow pressure and temperature, which can keep the wafer on the electrostatic chuck in an optimal micro-suspension state and a constant temperature state, effectively improving the process effect.

[0048] Example 2

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

[0050] In this embodiment, no manual valve is provided, and in case of emergency or when a problem occurs with the electric-controlled pneumatic valve, the pipeline cannot be closed, thereby increasing damage to the pipeline.

[0051] Example 3

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

[0053] In this embodiment, no sensor is provided, and it is impossible to automatically detect in real time whether a wafer is placed on the electrostatic chuck, thereby making it difficult to achieve the condition that the first pneumatic valve and the second pneumatic valve are opened at the same time, 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 method of supplying helium to the electrostatic chuck using the helium supply device is different from that in Example 1 in that, when no wafer is placed on the electrostatic chuck, the third pneumatic valve 12 is not opened to evacuate the gas in the vacuum pump group pipeline 5, and the rest is the same as in Example 1.

[0056] In this comparative example, no gas evacuation treatment is performed. During the process, helium gas 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 method of supplying helium to the electrostatic chuck using the helium supply device is different from that in Example 1 in that the first pneumatic valve 10 and the second pneumatic valve 11 are not in an interlocking relationship, and the three-layer front-stage condition is not set. The rest is the same as in Example 1.

[0059] In this comparative example, an interlocking relationship between the first pneumatic valve and the second pneumatic valve is not established and three-layer pre-stage conditions are not set, so that the gas inflow and outflow cannot be objectively and effectively achieved 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 blowing and temperature control on the bottom of the electrostatic chuck in a pneumatic and electrically controlled manner; when helium is introduced into the electrostatic chuck, the stable and constant flow pressure makes the wafer on the electrostatic chuck in an optimal micro-suspension state, and at the same time, the introduction of helium can stabilize the pressure in the cavity where the electrostatic chuck is located, maintaining process stability; since the temperature of the 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 supply method for the electrostatic chuck provided by the present invention, by setting the interlocking 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 the manual valve and the three-layer front-stage conditions, the reliability of the whole system can be effectively protected and the mass pressure controller can be protected from damage; by adding the sensor and the electronic pressure gauge, the whole system can be checked and controlled at any time by the host computer, so as to modularly control the helium supply device.

[0062] The above description is only a specific implementation mode 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 those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A helium supply device for an electrostatic chuck, It is characterized in that The helium supply device comprises 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 via a mass pressure controller, and the helium outlet pipeline comprises an electrostatic chuck purge pipeline and a vacuum pump group 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; the electrostatic chuck purge pipeline is provided with a second pneumatic valve, and the vacuum pump group pipeline is provided with a third pneumatic valve.

2. The helium supply device according to claim 1, It is characterized in that A manual valve is arranged on the pipeline before the pressure regulating valve.

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

4. The helium supply device according to claim 1, It is characterized in that The outlet of the electrostatic chuck purge pipeline is connected to the bottom of the electrostatic chuck; The outlet of the vacuum pump group pipeline is connected to a vacuum pipe, one end of the vacuum pipe is connected to the cavity where the electrostatic suction cup is located, and the other end is connected to the vacuum pump group.

5. The helium supply device according to claim 1, It is characterized in that A sensor is arranged in the cavity where the electrostatic chuck is located.

6. A helium supply method for an electrostatic chuck, It is characterized in that The helium supply method is performed by the helium supply device of the electrostatic chuck according to any one of claims 1 to 5, and the helium supply method comprises the following steps: The helium gas 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 enters the electrostatic chuck for purging. The first pneumatic valve and the second pneumatic valve are interlocked. When the following conditions are met, the first pneumatic valve and the second pneumatic valve are opened simultaneously: (1) the pressure in the chamber where the electrostatic chuck is located is ≤20 Torr; (2) a wafer is placed on the electrostatic chuck; (3) the initial helium inlet pressure 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 vacuum pump group.

7. The helium supply method according to claim 6, It is characterized in that The pressure in the cavity where the electrostatic chuck is located is controlled by a vacuum pump group connected by a vacuum pump group pipeline.

8. The helium supply method according to claim 6, It is characterized in that The detection of whether a wafer is placed on the electrostatic chuck or not is performed by a sensor arranged in the cavity where the electrostatic chuck is located.

9. The helium supply method according to claim 6, It is characterized in that The initial helium inlet pressure is controlled by a pressure regulating valve and read by an electronic pressure gauge; The pressure range after entering the mass pressure controller is ≤100Torr; The temperature of the helium gas introduced into the electrostatic chuck for purging is 20-30°C.

10. The helium supply method according to claim 6, It is characterized in that The helium flow is filtered before passing through the pressure regulating valve.

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