Method of controlling a cooling gas line, process chamber and semiconductor process apparatus

Abstract

The application discloses a kind of cooling gas pipeline control method, process chamber and semiconductor process equipment.The method comprises: in the continuous process using process chamber, keep dry pump, first valve, third valve and fourth valve in open state, while main pipeline is connected with cooling gas, control pressure controller is controlled according to set pressure, when needing to be electrostatic adsorption to wafer, the following steps are executed: step S1: control electrostatic chuck to be electrostatic adsorption to wafer;Step S2: open second valve;Step S3: control pressure controller is controlled according to set pressure, so that part of cooling gas flows into electrostatic chuck through first branch pipeline, to cool wafer.The application can shorten the time of wafer adsorption process, and reduce the probability of wafer adsorption wafer deviation in long time continuous process.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing equipment, and more specifically, relates to a method for controlling a cooling gas pipeline, a process chamber, and semiconductor process equipment. Background Technology

[0002] In the normal process of semiconductor etching, the wafer is first electrostatically held onto the surface of an electrostatic chuck (ESC) by the internal electrodes. Since the etching process involves bombarding the wafer surface with plasma, a significant amount of heat is generated. If this heat is not removed promptly, the wafer temperature will rise rapidly, ultimately causing the etching rate and uniformity to deviate from specifications. Therefore, helium gas is introduced into the ESC. This gas is evenly blown onto the back of the wafer through helium orifices in the ESC (back helium), carrying away the heat generated by the plasma bombardment.

[0003] The specific principle is as follows: Figure 1 As shown, helium gas introduced through the helium pipeline is evenly blown onto the back of the wafer (back helium) through a ring of helium holes around the edge of the electrostatic chuck. Since helium is lighter than air and etching gas, its molecular motion speed is faster, and its thermal conductivity is about 6 times that of air. After contacting the wafer, it is drawn away by the vacuum pipeline connected to the chamber, thereby carrying away the heat generated by the plasma bombarding the wafer.

[0004] Currently, existing etching machines only introduce helium and control the pressure in the helium pipeline when using the Chuck process. During the process of introducing helium and controlling the pressure to a stable flow, the airflow in the helium pipeline will fluctuate significantly, resulting in a long time for the pressure and airflow to stabilize. Furthermore, there is a risk that helium may blow the wafer away from its intended position through the helium orifice in the ESC, causing wafer deflection. Summary of the Invention

[0005] The purpose of this invention is to propose a control method for cooling gas pipelines, a process chamber, and semiconductor process equipment to shorten the wafer adsorption process time and reduce the probability of wafer displacement during long-term continuous processes.

[0006] In a first aspect, the present invention proposes a control method for a cooling gas pipeline in a semiconductor process chamber. The cooling gas pipeline includes a main pipeline, a first branch pipeline, a second branch pipeline, and a third branch pipeline. One end of the first branch pipeline is connected to the main pipeline, and the other end is connected to an electrostatic chuck inside the process chamber. One end of the second branch pipeline is connected to the main pipeline, and the other end is connected to a dry pump. The main pipeline is equipped with a first valve and a pressure controller. The first branch pipeline is equipped with a second valve, and the second branch pipeline is equipped with a third valve and a fourth valve. One end of the third branch pipeline is connected to the first branch pipeline between the electrostatic chuck and the second valve, and the other end of the third branch pipeline is connected to the second branch pipeline between the dry pump and the fourth valve. The third branch pipeline is equipped with a fifth valve. The method includes:

[0007] During continuous processing in the process chamber, the dry pump, the first valve, the third valve, and the fourth valve are kept open, while cooling gas is supplied to the main pipeline. The pressure controller is controlled to maintain pressure according to a set pressure. When electrostatic adsorption of the wafer is required, the following steps are performed:

[0008] Step S1: Control the electrostatic chuck to electrostatically adsorb the wafer;

[0009] Step S2: Open the second valve;

[0010] Step S3: Control the pressure controller to control the pressure according to the set pressure, so that part of the cooling gas flows into the electrostatic chuck through the first branch pipe to cool the wafer.

[0011] Optionally, during the continuous process in the process chamber, the method further includes:

[0012] Step S4: Monitor in real time whether the second valve is in the open state. If the second valve is in the open state, no operation is performed. If the second valve is in the closed state, proceed to step 5.

[0013] Step S5: Wait for the set duration;

[0014] Step S6: Determine again whether the second valve is in the open state. If it is in the open state, no operation is performed. If it is in the closed state, close the third valve and the first valve.

[0015] Optionally, it further includes: after a process is completed in the process chamber and before the next process is performed, performing the following steps:

[0016] Step S7: Determine whether the pressure in the main pipeline is the set pressure. If yes, proceed with steps S1-S3. If the pressure in the main pipeline is zero, proceed with the following steps:

[0017] Step 21: Open the third valve;

[0018] Step S22: Control the electrostatic chuck to electrostatically adsorb the wafer;

[0019] Step S23: Open the first valve;

[0020] Step S24: Open the second valve;

[0021] Step S25: Control the pressure controller to regulate the pressure according to the set pressure, so that a portion of the cooling gas flows into the electrostatic chuck through the first branch pipe to cool the wafer. Optionally, the set pressure is 8 Torr.

[0022] Optionally, the cooling gas is helium.

[0023] Optionally, the first valve, the second valve, the third valve, and the fifth valve are all pneumatic solenoid valves, and the fourth valve is a needle valve.

[0024] Optionally, the pressure controller integrates a capacitive pressure gauge and a flow controller.

[0025] Optionally, on the main pipeline, a pressure reducing valve and a pressure gauge are sequentially installed between the air inlet of the main pipeline and the first valve.

[0026] In a second aspect, the present invention provides a semiconductor process chamber, including an electrostatic chuck, a cooling gas pipeline for introducing cooling gas into the electrostatic chuck, and a control unit, wherein the control unit is used to execute the control method for the cooling gas pipeline of the semiconductor process chamber described in the first aspect.

[0027] Thirdly, the present invention provides a semiconductor process apparatus, including the semiconductor process chamber described in the second aspect.

[0028] The beneficial effects of this invention are as follows:

[0029] The method of this invention, during continuous processing in a process chamber, keeps the dry pump, first valve, third valve, and fourth valve open, and the pressure controller in a pressure-controlled state according to a set pressure. When electrostatic adsorption of the wafer is required, the electrostatic chuck is first controlled to electrostatically adsorb the wafer, then the second valve is opened, and then the pressure controller is controlled to control the pressure according to the set pressure, allowing some cooling gas to flow into the electrostatic chuck through the second branch pipeline to cool the wafer. This improves the control method of the cooling gas pipeline in the existing wafer adsorption process. Under long-term continuous processing in the process chamber, it can effectively shorten the time to control the pressure to the set pressure during wafer adsorption, and avoid the problem of large flow rate fluctuations during the process of stabilizing the pressure to the set pressure during wafer adsorption. It can effectively reduce the probability of wafer deflection during each wafer adsorption.

[0030] The system of the present invention has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0031] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0032] Figure 1 This diagram shows the structure of the existing semiconductor etching machine process chamber and helium gas pipeline.

[0033] Figure 2 A schematic diagram of the helium pipeline structure of a conventional semiconductor etching machine process chamber is shown.

[0034] Figure 3 A flowchart illustrating wafer adsorption in the prior art is shown.

[0035] Figure 4 The diagram shows the gas pressure and flow rate fluctuations during the wafer adsorption process in the prior art.

[0036] Figure 5 A structural diagram of a cooling gas pipeline in a control method for a semiconductor process chamber cooling gas pipeline according to an embodiment of the present invention is shown.

[0037] Figure 6 A flowchart of a control method for a semiconductor process chamber cooling gas pipeline according to an embodiment of the present invention is shown.

[0038] Figure 7 A flowchart illustrating the control method for a semiconductor process chamber cooling gas pipeline according to an embodiment of the present invention is shown, in which control is performed based on the state of a second valve.

[0039] Figure 8 A control flowchart for re-processing is shown in a control method for a semiconductor process chamber cooling gas pipeline according to an embodiment of the present invention.

[0040] Figure 9 The diagram illustrates the gas pressure and flow rate fluctuations during a wafer adsorption process in a control method for a semiconductor process chamber cooling gas pipeline according to an embodiment of the present invention. Detailed Implementation

[0041] Figure 2 A schematic diagram of the helium pipeline in the existing etching machine process chamber is shown. A pressure reducing valve regulates the helium pressure from the plant to the required range. The flow direction of air and helium is controlled by four pneumatic solenoid valves: the Primary valve, Stabilize valve, Secondary valve, and EVAC valve. A needle valve is used to regulate the helium flow rate. The pressure controller includes a capacitive pressure gauge and a flow meter, allowing different flow rates to pass through at the same set pressure.

[0042] During the current commissioning process, the controller pressure is set to a stable 8T. The Primary and Stabilize valves are opened, and the flow rate is stabilized at 1 sccm by adjusting the needle valve and using a dry pump. Excessive flow rate can cause the wafer to shift due to electrostatic attraction from the electrodes. During the process, the Secondary valve is opened. Since the controller is set to 8T, the flow rate will slightly increase to 1.2 sccm. This extra 0.2 sccm is considered as back helium introduced into the ESC to participate in wafer cooling. After the process is complete, the Primary, Secondary, and Stabilize valves are closed. Then, the EVAC valve is opened to remove any residual helium between the Secondary and ESC valves.

[0043] Currently, the existing Chuck process is as follows: Figure 3 As shown, first, the Stabilize valve is opened to connect the pipeline to the dry pump, removing any residual helium gas in the pipeline. Then, the ESC is used to electrostatically adsorb the wafer. After that, the Primary and Secondary valves are opened in sequence, and the pressure controller is set to 8T. Once the controller stabilizes the helium pressure at 8T, the process ends, and plasma bombardment etching can begin.

[0044] Before the process, all valves are closed; at the start of the process, they are opened sequentially according to the flow chart to control the pressure at 8T; after the process, the EVAC valve is opened to remove the residual helium, and it automatically closes after 10 seconds.

[0045] The existing technology has the following drawbacks:

[0046] Currently, helium is only introduced and pressure controlled when using the Chuck process, at which point... Figure 4 As shown, the flow rate fluctuates significantly during the process of stabilizing the pressure to 8T, eventually settling at 1.2 sccm. The maximum fluctuation can reach 10 sccm, and the process of stabilizing the pressure and flow rate takes approximately 92 units of time. Furthermore, a flow rate of 10 sccm of helium passing through the helium orifice in the ESC poses a risk of blowing the wafer away from its intended position, causing wafer deflection.

[0047] This invention, by changing the control method of the cooling gas pipeline, can avoid the helium flow fluctuations in the prior art, shorten the pressure control time, and reduce the risk of wafer deflection.

[0048] The invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0049] Example 1

[0050] This embodiment proposes a control method for a cooling gas pipeline in a semiconductor process chamber. The cooling gas pipeline involved in this invention has the same structure as the existing helium pipeline for etching machines, specifically as follows: Figure 5 As shown, the cooling gas pipeline includes a main pipeline 1, a first branch pipeline 2, a second branch pipeline 3, and a third branch pipeline 4. One end of the first branch pipeline 2 is connected to the main pipeline 1, and the other end is connected to an electrostatic chuck 11 in the process chamber. One end of the second branch pipeline 3 is connected to the main pipeline 1, and the other end is connected to a dry pump 12. The main pipeline 1 is equipped with a first valve 5 and a pressure controller 10. The first branch pipeline 2 is equipped with a second valve 6, and the second branch pipeline 3 is equipped with a third valve 7 and a fourth valve 8 in sequence. One end of the third branch pipeline 4 is connected to the first branch pipeline 2 between the electrostatic chuck 11 and the second valve 6, and the other end of the third branch pipeline 4 is connected to the second branch pipeline 3 between the dry pump 12 and the fourth valve 8. The third branch pipeline 4 is equipped with a fifth valve 9. Optionally, a pressure reducing valve 13 and a pressure gauge 14 are also sequentially installed between the air inlet of the main pipeline 1 and the first valve 5.

[0051] based on Figure 5 The cooling gas piping shown is as follows: Figure 6 As shown, the control method for the cooling gas pipeline in this embodiment includes:

[0052] Step S100: During continuous processing in the process chamber, keep the dry pump 12, first valve 5, third valve 7, and fourth valve 8 open, while simultaneously supplying cooling gas to the main pipeline 1. Control the pressure controller 10 to regulate the pressure according to the set pressure. When electrostatic adsorption of the wafer is required, perform the following steps:

[0053] Step S101: Control the electrostatic chuck 11 to electrostatically adsorb the wafer;

[0054] Step S102: Open the second valve 6;

[0055] Step S103: Control the pressure controller 10 to control the pressure according to the set pressure, so that part of the cooling gas flows into the electrostatic chuck 11 through the first branch pipe 2 to cool the wafer.

[0056] Preferably, the set pressure of the pressure controller in this embodiment is 8 Torr. The pressure controller 10 integrates a capacitive pressure gauge and a flow controller. The cooling gas is helium. The first valve 5, the second valve 6, the third valve 7 and the fifth valve 9 are all pneumatic solenoid valves, and the fourth valve 8 is a needle valve.

[0057] Specifically, if the existing control method is used, the flow rate fluctuation of the cooling gas occurs at the very beginning of pressure control. At this time, the cooling gas needs to reach the ESC through the second valve 6, and also through the third valve 7 to reach the needle valve, and finally be drawn away by the dry pump 12. Flow rate fluctuations are inevitable when the cooling gas fills such a long pipeline. Based on the control method of this embodiment, during use, the first valve 5 and the third valve 7 can be kept open at all times, and the pressure controller 10 is also in a pressure control state at the set pressure. When performing the wafer adsorption process, it can be simplified as follows: Figure 6 The process is shown below.

[0058] At this point, the Chuck process is simplified to the ESC (electrostatic chuck 11) electrostatically attracting the wafer, then opening the second valve 7 (while keeping the first valve 5, third valve 7, and fourth valve 8 open), and maintaining the pressure controller 10 at 8 Torr. This significantly reduces the time required for controlling each valve and stabilizing the controller at 8 Torr during the Chuck process.

[0059] During prolonged continuous processes, if the first valve 5 and the third valve 7 remain open for extended periods without any processing activity, helium will be wasted, increasing operating costs. Therefore, if... Figure 8As shown, in this embodiment, during the continuous process in the process chamber, the following further steps are included:

[0060] Step S104: Monitor in real time whether the second valve 6 is in the open state. If the second valve 6 is in the open state, no operation is performed. If the second valve 6 is in the closed state, proceed to step 105.

[0061] Step S105: Wait for the set duration;

[0062] Step S106: Determine again whether the second valve 6 is in the open state. If it is in the open state, no operation is performed. If it is in the closed state, close the third valve 7 and the first valve 5.

[0063] Specifically, the status of the second valve 6 can be used to determine whether helium is being used for cooling in the process chamber. When the wafer is being chucked, the second valve 6 will be opened, and after the process is completed, the second valve 6 will be closed.

[0064] The specific process is as follows: Figure 7 As shown in the diagram, the timing can be set by the user according to the machine's busy status. If the second valve 6 is detected to be open, the machine is in the process state, and the process ends; if the second valve 6 is detected to be closed, the machine is in the non-process state. At this time, according to the set timing time, after the time is up, the opening and closing status of the second valve 6 is determined: if it is open, it means that the machine has re-entered the process, and the process ends; if it is closed, the machine is always in the non-process state. At this time, the first valve 5 and the third valve 7 are closed to save helium.

[0065] like Figure 8 As shown, the control method in this embodiment further includes: after a process chamber finishes one process and before the next process begins, performing the following steps:

[0066] Step S107: Determine if the pressure in main pipe 1 is the set pressure. If yes, proceed to steps S101-S103. If the pressure in main pipe 1 is zero, proceed to the following steps:

[0067] Step 201: Open the third valve 7;

[0068] Step S202: Control the electrostatic chuck 11 to electrostatically attract the wafer;

[0069] Step S203: Open the first valve 5;

[0070] Step S204: Open the second valve 6;

[0071] Step S205: Control the pressure controller 10 to control the pressure according to the set pressure, so that part of the cooling gas flows into the electrostatic chuck through the first branch pipe 2 to cool the wafer.

[0072] Specifically, according to steps S104-S106, during two consecutive process intervals, the cooling gas pipeline may be in two states: the first valve 5 and the third valve 7 may be open or closed simultaneously. Therefore, it is necessary to determine the state of the pressure controller 10 during the Chuck process: if the pressure is maintained at 8 Torr, it means that the cooling gas pipeline is in the state where the first valve 5 and the third valve 7 are open simultaneously. At this time, it is only necessary to perform Chuck according to the process of steps S101-S103; if the pressure is not maintained at 8 Torr (i.e., 0 Torr), it means that the cooling gas pipeline is in the state where the first valve 5 and the third valve 7 are closed simultaneously, indicating that the machine has been idle for a long time. When performing a new process Chuck, it is necessary to perform Chuck operation according to the process of steps 201-S205.

[0073] Taking an etching machine as an example, the process is executed according to the control method of this embodiment (the updated process program can be written into the lower-level machine of the etching machine). The pressure and flow fluctuations during the Chuck process are as follows: Figure 9 As shown, the pressure controller 10 stabilizes at 8T in approximately 43 time units, with a maximum flow rate of only 1.8 sccm. This saves half the controller stabilization time while maintaining stable gas flow, effectively reducing the probability of wafer shift.

[0074] In summary, the cooling pipeline control method of this embodiment improves the control of cooling gas, reducing the time to reach the set pressure during the Chuck process to half that of the existing process. It also adds a method for judging the process progress, avoiding unnecessary helium waste. At the same time, it is compatible with the Chuck process when the machine is idle for a long time and then resumes the process. This satisfies the requirement that the machine is in the process state for a long time, reduces the Chuck time and lowers the probability of wafer shift.

[0075] Example 2

[0076] This embodiment proposes a semiconductor process chamber, including an electrostatic chuck, a cooling gas pipeline for introducing cooling gas into the electrostatic chuck, and a control unit. The control unit is used to execute the control method of the cooling gas pipeline of the semiconductor process chamber in Embodiment 1.

[0077] The cooling gas piping is as described in the above embodiment. Figure 5The cooling gas pipeline shown can be controlled by a lower-level computer. All pneumatic solenoid valves are controlled by the lower-level computer sending DO commands to the relevant pneumatic solenoid valves to open or close them.

[0078] Example 3

[0079] This embodiment proposes a semiconductor process apparatus, including the semiconductor process chamber of Embodiment 2.

[0080] Among them, semiconductor process equipment can be semiconductor process equipment with cooling gas pipelines, such as etching machines.

[0081] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A control method for a cooling gas pipeline in a semiconductor process chamber, the cooling gas pipeline comprising a main pipeline, a first branch pipeline, a second branch pipeline, and a third branch pipeline, wherein one end of the first branch pipeline is connected to the main pipeline and the other end is connected to an electrostatic chuck inside the process chamber, one end of the second branch pipeline is connected to the main pipeline and the other end is connected to a dry pump, the main pipeline is provided with a first valve and a pressure controller, the first branch pipeline is provided with a second valve, the second branch pipeline is provided with a third valve and a fourth valve in sequence, one end of the third branch pipeline is connected to the first branch pipeline between the electrostatic chuck and the second valve, the other end of the third branch pipeline is connected to the second branch pipeline between the dry pump and the fourth valve, and the third branch pipeline is provided with a fifth valve, characterized in that... The method includes: Step S0: During the continuous process in the process chamber, the dry pump, the first valve, the third valve, and the fourth valve are kept open, while cooling gas is introduced into the main pipeline. The pressure controller is controlled to maintain the pressure according to the set pressure. When electrostatic adsorption of the wafer is required, the following steps are performed: Step S1: Control the electrostatic chuck to electrostatically adsorb the wafer; Step S2: Open the second valve, while keeping the first, third, and fourth valves open; Step S3: Control the pressure controller to control the pressure according to the set pressure, so that part of the cooling gas flows into the electrostatic chuck through the first branch pipe to cool the wafer.

2. The control method for the cooling gas pipeline of the semiconductor process chamber according to claim 1, characterized in that, During the continuous process in the process chamber, the following is also included: Step S4: Monitor in real time whether the second valve is in the open state. If the second valve is in the open state, no operation is performed. If the second valve is in the closed state, proceed to step 5. Step S5: Wait for the set duration; Step S6: Determine again whether the second valve is in the open state. If it is in the open state, no operation is performed. If it is in the closed state, close the third valve and the first valve.

3. The control method for the cooling gas pipeline of the semiconductor process chamber according to claim 2, characterized in that, It also includes: after a process is completed in the process chamber and before the next process is performed, performing the following steps: Step S7: Determine whether the pressure in the main pipeline is the set pressure. If yes, proceed with steps S1-S3. If the pressure in the main pipeline is zero, proceed with the following steps: Step 21: Open the third valve; Step S22: Control the electrostatic chuck to electrostatically adsorb the wafer; Step S23: Open the first valve; Step S24: Open the second valve; Step S25: Control the pressure controller to control the pressure according to the set pressure, so that part of the cooling gas flows into the electrostatic chuck through the first branch pipe to cool the wafer.

4. The control method for the cooling gas pipeline of a semiconductor process chamber according to any one of claims 1-3, characterized in that, The set pressure is 8 Torr.

5. The control method for the cooling gas pipeline of a semiconductor process chamber according to any one of claims 1-3, characterized in that, The cooling gas is helium.

6. The control method for the cooling gas pipeline of a semiconductor process chamber according to any one of claims 1-3, characterized in that, The first valve, the second valve, the third valve, and the fifth valve are all pneumatic solenoid valves, and the fourth valve is a needle valve.

7. The control method for the cooling gas pipeline of a semiconductor process chamber according to any one of claims 1-3, characterized in that, The pressure controller integrates a capacitive pressure gauge and a flow controller.

8. The control method for the cooling gas pipeline of a semiconductor process chamber according to any one of claims 1-3, characterized in that, On the main pipeline, a pressure reducing valve and a pressure gauge are sequentially installed between the air inlet of the main pipeline and the first valve.

9. A semiconductor process chamber, characterized in that, The device includes an electrostatic chuck, a cooling gas pipeline for introducing cooling gas into the electrostatic chuck, and a control unit, wherein the control unit is used to execute the control method for the cooling gas pipeline of the semiconductor process chamber according to any one of claims 1-8.

10. A semiconductor process apparatus, characterized in that, Includes the semiconductor process chamber as described in claim 9.

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