TWI849660B - Plasma etching apparatus - Google Patents

Abstract

A plasma etching apparatus includes a cooling device, a lower electrode plate, an upper electrode plate, a radio frequency source, a flow sensor, and a controller. The cooling device has a cooling pipe group. The lower electrode plate has a coolant channel. The coolant channel has an inlet and an outlet and is connected to the cooling device through the cooling pipe group. The coolant channel is configured for a coolant to flow from the cooling device into the cooling channel through the inlet, flow out through the outlet, and then return to the cooling device through the cooling pipe group. The flow sensor is disposed in the cooling pipe group and between the cooling device and the inlet. The flow sensor is configured to obtain the flow rate of the coolant. The controller is communicatively connected to the flow sensor, configured to receive a signal about the flow value from the flow sensor and switch off a power supply of the plasma etching apparatus according to the signal.

Description

Plasma Etching Machine

The present disclosure relates to a plasma etching machine.

The technologies used for wafer etching can be divided into dry etching process and wet etching process. Compared with the wafer etching machine used for wet etching process, the wafer etching machine used for dry etching process has better process control and can transfer the pattern on the photoresist more completely, which is more suitable for the manufacture of varied large scale integrated circuit (VLSI) and ultra large scale integrated circuit (ULSI).

Among them, the most common dry etching process is the plasma etching process. In the plasma etching process, in addition to controlling the temperature in the process chamber, properly controlling the temperature range of both the electrode plate and the wafer helps maintain a higher yield.

Therefore, how to come up with a plasma etching machine that can achieve the above-mentioned purpose is one of the problems that the industry is eager to invest R&D resources to solve.

In view of this, one purpose of the present disclosure is to provide a plasma etching machine that can achieve the above-mentioned purpose.

According to some embodiments of the present disclosure, a plasma etching machine includes a cooling device, a lower electrode plate, an upper electrode plate, a radio frequency source, a flow sensor, and a controller. The cooling device has a cooling tube. The lower electrode plate is configured to carry a semiconductor workpiece. The lower electrode plate has a cooling liquid flow channel. The cooling liquid flow channel has an inlet and an outlet, and is connected to the cooling device through the cooling tube. The cooling liquid flow channel is configured to allow cooling liquid to flow from the cooling device into the cooling liquid flow channel through the inlet, flow out through the outlet, and then return to the cooling device through the cooling tube. The upper electrode plate is above the lower electrode plate. The radio frequency source is configured to generate a bias between the lower electrode plate and the upper electrode plate. The flow sensor is disposed in the cooling pipe and between the cooling device and the inlet. The flow sensor is configured to obtain the flow value of the cooling liquid. The controller is signal-connected to the flow sensor, configured to receive a signal about the flow value from the flow sensor, and cut off the power supply of the plasma etching machine according to the signal.

In some implementations, the controller is a relay configured to cut off the power supply of the plasma etching machine by disconnecting contacts of the relay.

In some embodiments, the relay is configured to disconnect the contact and cut off the power supply of the plasma etching machine when receiving a signal from the flow sensor indicating that the flow value is greater than 15 liters per minute or less than 2 liters per minute.

In some embodiments, the flow sensor further includes an alarm configured to send an alarm signal when the flow value obtained by the flow sensor is greater than 15 liters per minute or less than 2 liters per minute.

According to other embodiments of the present disclosure, a plasma etching machine includes a cooling device, an upper electrode plate, a lower electrode plate, a radio frequency source, a flow sensor, and a first controller. The cooling device has a cooling pipe. The upper electrode plate includes a gas input channel and a cooling liquid flow channel. The gas input channel passes through the upper electrode plate and is configured to allow process gas to flow through. The cooling liquid flow channel is distributed in the upper electrode plate. The cooling liquid flow channel has an inlet and an outlet, and is connected to the cooling device through the cooling pipe. The cooling liquid flow channel is configured to allow cooling liquid to flow from the cooling device through the inlet into the cooling liquid flow channel, flow out through the outlet, and then return to the cooling device through the cooling pipe. The lower electrode plate is below the upper electrode plate. The radio frequency source is configured to generate a bias voltage between the upper electrode plate and the lower electrode plate. The flow sensor is disposed in the cooling pipe and is located between the cooling device and the inlet, and is configured to obtain the flow value of the cooling liquid. The first controller is signal-connected to the flow sensor, and is configured to receive a signal about the flow value from the flow sensor, and cut off the power supply of the plasma etching machine according to the signal.

In some embodiments, the first controller is a relay configured to cut off the power supply of the plasma etching machine by disconnecting the contacts of the relay.

In some embodiments, the relay is configured to disconnect the contact and cut off the power supply of the plasma etching machine when receiving a signal from the flow sensor that the flow value is greater than 15 liters per minute or less than 2 liters per minute.

In some embodiments, the flow sensor further includes an alarm configured to send a warning signal when the flow value obtained by the flow sensor is greater than 15 liters per minute or less than 2 liters per minute.

In some embodiments, the plasma etching machine further includes a second controller disposed in the gas input channel of the upper electrode plate and signal-connected to the flow sensor. The second controller is configured to receive a signal about the flow value from the flow sensor and close the gas input channel according to the signal.

In some implementations, the second controller is a solenoid valve.

In summary, in some embodiments of the present disclosure, by adding a flow sensor and a controller, it is possible to grasp at any time whether the cooling liquid circulation system of the electrode plate is operating normally, and before the temperature of the electrode plate changes significantly due to the abnormality of the cooling liquid circulation system, the operation of the plasma etching machine is suspended in time to avoid the etching process failing to achieve the expected effect due to temperature changes, resulting in the workpiece having to be scrapped. In addition, by using an alarm connected to the flow sensor signal, when the flow of the cooling liquid is abnormal, the user can be reminded that there is an abnormality in the operation of the plasma etching machine. Compared with the common plasma etching machines currently available, it can achieve early warning and stop damage when the temperature of the plasma etching process is abnormal, reducing the probability of workpiece scrapping.

These and other aspects of the present disclosure will become apparent from the following description of preferred embodiments in conjunction with the drawings, but variations and modifications may be made therein without departing from the spirit and scope of the novel concepts of the present disclosure.

The following disclosure will now be more fully described here through drawings and references, and some exemplary embodiments are illustrated in the drawings. The disclosure can be implemented in different forms and should not be limited by the embodiments mentioned below. However, these embodiments are provided to help a more complete understanding of the content of the disclosure and fully convey the scope of the invention to those skilled in the art. The same reference numerals will refer to similar elements throughout the text.

Please refer to FIG. 1 , which is a schematic diagram of a plasma etching machine 100 according to some embodiments of the present disclosure. As shown in FIG. 1 , the plasma etching machine 100 includes a process chamber 110 , a cooling device 140 , a process gas source 150 , a power source 170 , and a radio frequency source 180 .

As shown in FIG. 1 , a plasma etching machine 100 is provided with two parallel plate electrodes for plasma processing. A lower electrode plate 120 and an upper electrode plate 130 are provided in a process chamber 110. The upper electrode plate 130 is located above the lower electrode plate 120. The lower electrode plate 120 and the upper electrode plate 130 are parallel to and opposite to each other. Specifically, the lower electrode plate 120 has a first plane 120a and a second plane 120b opposite to each other, and the upper electrode plate 130 has a first plane 130a and a second plane 130b opposite to each other, wherein the first plane 120a of the lower electrode plate 120 is located on a side of the lower electrode plate 120 away from the upper electrode plate 130, and the second plane 130b of the upper electrode plate 130 is located on a side of the upper electrode plate 130 away from the lower electrode plate 120.

The lower electrode plate 120 and the upper electrode plate 130 are provided with cooling liquid channels 121 and 131 for the cooling liquid WF1 and the cooling liquid WF2 to flow, respectively. In other words, both ends of the cooling liquid channel 121 are connected to the cooling device 140 through the cooling pipe 141-1 of the cooling device 140 located outside the process chamber 110, forming a closed loop (as shown by the arrow in FIG. 1). In other words, the cooling liquid WF1 flows out from the cooling device 140 to the cooling pipe 141-1, enters the lower electrode plate 120 through the inlet 121a of the cooling liquid flow channel 121, and the cooling liquid WF1 performs heat exchange in the cooling liquid flow channel 121, and then leaves the lower electrode plate 120 through the outlet 121b of the cooling liquid flow channel 121, re-enters the cooling pipe 141-1, and returns to the cooling device 140 for heat exchange.

Similarly, both ends of the cooling liquid flow channel 131 are connected to the cooling device 140 through the cooling pipe 141-2 of the cooling device 140 located outside the process chamber 110, forming a closed loop (as shown by the arrow in FIG. 1). In other words, the cooling liquid WF2 flows out of the cooling device 140 to the cooling pipe 141-2, enters the upper electrode plate 130 through the inlet 131a of the cooling liquid flow channel 131, and the cooling liquid WF2 performs heat exchange in the cooling liquid flow channel 131, and then leaves the upper electrode plate 130 through the outlet 131b of the cooling liquid flow channel 131, re-enters the cooling pipe 141-2, and returns to the cooling device 140 for heat exchange.

The second plane 120b of the lower electrode plate 120 is configured to carry the semiconductor workpiece 900. For example, the semiconductor workpiece 900 may be a semiconductor material, a wafer or a chip.

The upper electrode plate 130 is provided with a gas input channel 132. As shown in FIG. 1 , the gas input channel 132 passes through the electrode plate 130, so that the process gas G (as shown by the arrow in FIG. 1 ) can enter the process chamber 110 from the process gas source 150 through the gas input channel 132. In some embodiments, the gas input channel 132 has a branch 132a at one end close to the first plane 130a of the upper electrode plate 130, and the process gas G is divided through the branch 132a and enters the process chamber 110.

After the process gas G enters the process chamber 110, the radio frequency source 180 generates an electric field and provides a bias voltage between the lower electrode plate 120 and the upper electrode plate 130. The process gas G forms plasma and, under the acceleration of the bias voltage, performs ion bombardment on the semiconductor workpiece 900. For example, the process gas G includes argon (Ar), which ionizes or dissociates into positive argon ions (Ar+), which perform ion bombardment on the semiconductor workpiece 900.

Since the lower electrode plate 120, the upper electrode plate 130 and the semiconductor workpiece 900 may generate high temperatures due to ion bombardment during the plasma etching process, the circulation of cooling liquid helps to avoid damage to the semiconductor workpiece 900 caused by excessive temperature. In addition, reducing the temperature gradient on the electrode plate helps to increase the etching uniformity to avoid different chemical reaction rates between ions and different parts of the semiconductor workpiece 900. In particular, for high aspect ratio etching processes, it helps to ensure the uniformity of etching depth and improve the product yield.

Furthermore, knowing whether the circulation of the coolant WF1 and the coolant WF2 is operating normally at any time helps ensure that the lower electrode plate 120 and the upper electrode plate 130 are stably maintained within a specific temperature range. Furthermore, if the abnormal operation of the cooling device 140 can be discovered immediately, such as the flow rate of the coolant WF1 or the coolant WF2 is too low, the operation of the machine may be suspended before the cooling effect decreases and the temperature of the lower electrode plate 120 or the upper electrode plate 130 changes significantly, so as to avoid the ion bombardment or the chemical reaction on the surface of the workpiece failing to achieve the expected effect after the temperature of the lower electrode plate 120 or the upper electrode plate 130 exceeds the ideal range, thereby causing the current workpiece to be directly scrapped.

Therefore, in some embodiments, a flow sensor 142-1 is disposed in the cooling tube 141-1 between the cooling device 140 and the inlet 121a of the cooling liquid flow channel 121. Similarly, a flow sensor 142-2 is disposed in the cooling tube 141-2 between the cooling device 140 and the inlet 131a of the cooling liquid flow channel 131, as shown in FIG. 1 .

In this way, the flow sensors 142-1 and 142-2 respectively detect whether the flow rates of the coolant WF1 and the coolant WF2 flowing out of the cooling device 140 are within a preset range. If any of the detected flow values is not within the preset flow range, it may indicate that there is an abnormality in the cooling device 140 or the cooling pipes 141-1 and 141-2.

At this stage, the temperature of the lower electrode plate 120 and the upper electrode plate 130 has not been affected by the abnormal circulation of the cooling liquid, but is still maintained within the normal temperature range, that is, the etching process is still proceeding normally. At this time, immediately stopping the machine helps to prevent the semiconductor workpiece 900 being etched from experiencing an unexpected etching process. In some embodiments, the machine may be stopped by shutting down the RF source 180, cutting off the power supply 170 of the machine, and/or stopping the supply of the process gas G.

In some embodiments, the flow rate of the cooling liquid WF1 is controlled within a range of 15 liters per minute (L/min) to 2 L/min to maintain the temperature of the lower electrode plate 120 between -20°C and 85°C. In some embodiments, the flow rate of the cooling liquid WF2 is controlled within a range of 15 L/min to 2 L/min to maintain the temperature of the upper electrode plate 130 between 35°C and 45°C.

As shown in FIG. 1 , in some embodiments, the plasma etching machine 100 further includes a controller 160-1. The controller 160-1 is signal-connected to the flow sensor 142-1 and the power supply 170 of the machine. When the flow value of the cooling liquid WF1 flowing out of the cooling device 140 is not within the preset range, the flow sensor 142-1 transmits an abnormal signal to the controller 160-1, and the controller 160-1 further cuts off the power supply 170. Similarly, the plasma etching machine 100 further includes a controller 160-2. The controller 160-2 is signal-connected to the flow sensor 142-2 and the power supply 170.

In some embodiments, the controller 160-1 and the controller 160-2 may be relays. For example, the controller 160-1 and the controller 160-2 are normally closed single pole single throw (SPST) relays, which disconnect the contact mechanism of the relay and cut off the power supply 170 after receiving an abnormal signal from the flow sensor 142-1 or the flow sensor 142-2.

In some embodiments, suspending the machine further includes stopping the supply of process gas G. As shown in FIG. 1 , the plasma etching machine 100 further includes a controller 133. The controller 133 is disposed in the gas input channel 132. The controller 133 is signal-connected to the flow sensor 142-2. When the flow value of the coolant WF2 flowing out of the cooling device 140 is not within a preset range, the flow sensor 142-2 transmits an abnormal signal to the controller 160-2 and also transmits an abnormal signal to the controller 133. The controller 133 then closes the gas input channel 132 and stops inputting the process gas G into the process chamber 110. Similarly, the controller 133 can also be signal-connected to the flow sensor 142-1 (not shown).

In some embodiments, the controller 133 may be a solenoid valve. For example, the controller 133 is a normally open two-position, two-way solenoid valve. After receiving an abnormal signal from the flow sensor 142-1 or the flow sensor 142-2, the solenoid valve is energized to control the movement of its internal valve body to close the passage of the gas input channel 132. At the same time, after the power supply 170 is cut off, the supply of the process gas source 150 is also suspended, and the input of the process gas G into the process chamber 110 is stopped.

As shown in FIG. 1 , in some embodiments, the plasma etching machine 100 further includes an alarm 143-1. The alarm 143-1 signal is connected to the flow sensor 142-1. When the flow value of the coolant WF1 flowing out of the cooling device 140 is not within the preset range, the flow sensor 142-1 transmits an abnormal signal to the alarm 143-1, and the alarm 143-1 further sends a warning signal, such as an alarm sound, to remind the user that the operation of the plasma etching machine 100 is abnormal. Similarly, the plasma etching machine 100 further includes an alarm 143-2. The alarm 143-2 signal is connected to the flow sensor 142-2.

In addition, a pedestal 123 is provided below the lower electrode plate 120, and a backside helium cooling system 122 is provided in the pedestal 123. As shown in FIG. 1 , helium enters the pedestal 123 from the backside helium cooling system 122, and the temperature distribution of the semiconductor workpiece 900 is made uniform through the high heat conduction property of helium.

In some embodiments, the process chamber 110 is grounded, the lower electrode plate 120 is grounded via the base 123, and the upper electrode plate 130 is coupled to the RF source 180.

When the etching process is started, the process gas G flows out from the process gas source 150 and is input into the process chamber 110 through the gas input channel 132. Then, the RF source 180 is turned on and a fixed power is applied to complete the warm-up. Then, the power of the RF source 180 is converted, and a bias is applied between the upper electrode plate 130 and the lower electrode plate 120 to accelerate ions and etch the semiconductor workpiece 900. In some embodiments, the RF source 180 can provide mixed frequency power. For example, the RF source 180 can have a single or multiple frequencies in the range of 400kHz to 2MHz.

In some embodiments, the process gas G may be a single gas or a gas mixture of multiple gases, for example, Ar, octafluorocyclobutane (C ₄ F ₈ ) and oxygen (O ₂ ) for high-aspect-ratio etching processes, or Ar, carbon tetrafluoride (CF ₄ ), trifluoromethane (CHF ₃ ) and O ₂ for oxide etching.

In some embodiments, the plasma etching machine 100 further includes a byproduct exhaust system 190, which is disposed below the process chamber 110 for exhausting the byproducts. Specifically, the byproduct exhaust system 190 may include an exhaust pump, an exhaust pipe, etc. For example, the exhaust pump is located outside the process chamber 110, and the exhaust pipe connects the process chamber 110 and the exhaust pump. The exhaust pump is used to extract impurities and contaminants in the process chamber 110 into the exhaust pipe, so that the semiconductor workpiece 900 is free from contamination.

From the above detailed description of the specific implementation of the present disclosure, it can be clearly seen that in the plasma etching machine of some implementations of the present disclosure, by adding a flow sensor and a controller, it is possible to grasp at any time whether the cooling liquid circulation system of the electrode plate is operating normally, and before the temperature of the electrode plate changes significantly due to the abnormality of the cooling liquid circulation system, the operation of the plasma etching machine is suspended in time to avoid the etching process failing to achieve the expected effect due to temperature changes, resulting in the workpiece having to be scrapped. In addition, through the alarm connected to the flow sensor signal, when the flow of the cooling liquid is abnormal, the user can be reminded that there is an abnormality in the operation of the plasma etching machine. Compared with the common plasma etching machines currently available, it can achieve early warning and stop damage when the temperature of the plasma etching process is abnormal, reducing the probability of workpiece scrapping.

The foregoing description is only provided to illustrate and describe the exemplary embodiments of the present disclosure, and is not intended to limit the precise form of the invention disclosed by the present disclosure. The above teachings may be modified or varied.

The embodiments selected and described are used to explain the content of the present disclosure and their practical applications to inspire other technical personnel in the field to utilize the present disclosure and various embodiments, and to make various modifications to meet the expected specific use. Alternative embodiments will be obvious to technical personnel in the field to which the present disclosure belongs without departing from the spirit and scope of the present disclosure. Therefore, the scope of the present invention is determined according to the scope of the attached invention application, rather than being limited by the above specification and the exemplary embodiments described therein.

100: Plasma etching machine 110: Process chamber 120: Lower electrode plate 120a, 130a: First plane 120b, 130b: Second plane 121, 131: Cooling liquid flow channel 121a, 131a: Inlet 121b, 131b: Outlet 122: Back helium cooling system 123: Base 130: Upper electrode plate 132: Gas input channel 132a: Branch 133: Controller 140: Cooling device 141-1, 141-2: Cooling pipe 142-1, 142-2: Flow sensor 143-1, 143-2: Alarm 150: Process gas source 160-1, 160-2: Controller 170: Power supply 180: RF source 190: Byproduct exhaust system 900: Semiconductor workpiece WF1, WF2: Coolant G: Process gas

The drawings illustrate one or more embodiments of the present disclosure and are used together with the written description to explain the principles of the present disclosure. In all drawings, the same figure labels are used to refer to similar or identical elements of the embodiments as much as possible, wherein: FIG. 1 is a schematic diagram of a plasma etching machine according to some embodiments of the present disclosure.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

100: Plasma etching machine 110: Process chamber 120: Lower electrode plate 120a, 130a: First plane 120b, 130b: Second plane 121, 131: Cooling liquid flow channel 121a, 131a: Inlet 121b, 131b: Outlet 122: Back helium cooling system 123: Base 130: Upper electrode plate 132: Gas input channel 132a: Branch 133: Controller 140: Cooling device 141-1, 141-2: Cooling pipe 142-1, 142-2: Flow sensor 143-1, 143-2: Alarm 150: Process gas source 160-1, 160-2: Controller 170: Power supply 180: RF source 190: Byproduct exhaust system 900: Semiconductor workpiece WF1, WF2: Coolant G: Process gas

Claims (8)

A plasma etching machine comprises: a cooling device having a cooling pipe; a lower electrode plate configured to carry a semiconductor workpiece, the lower electrode plate having a cooling liquid flow channel, the cooling liquid flow channel having an inlet and an outlet, and connected to the cooling device through the cooling pipe, configured to allow a cooling liquid to flow from the cooling device into the cooling liquid flow channel through the inlet, flow out through the outlet, and then return to the cooling device through the cooling pipe; an upper electrode plate above the lower electrode plate; an RF A source configured to generate a bias between the lower electrode plate and the upper electrode plate; a flow sensor disposed in the cooling tube and located between the cooling device and the inlet of the cooling liquid flow channel, configured to obtain a flow value of the cooling liquid; and a relay signal-connected to the flow sensor, configured to receive a signal about the flow value from the flow sensor, and disconnect a contact of the relay when the flow value exceeds a preset range, thereby cutting off a power supply of the plasma etching machine. A plasma etching machine as described in claim 1, wherein the preset range is between 2 liters per minute and 15 liters per minute. The plasma etching machine as described in claim 1, wherein the flow sensor further comprises an alarm, which is configured to send out an alarm signal when the flow value obtained by the flow sensor is greater than 15 liters per minute or less than 2 liters per minute. A plasma etching machine comprises: a cooling device having a cooling pipe; an upper electrode plate comprising: a gas input channel penetrating the upper electrode plate and configured to allow a process gas to flow through; and a cooling liquid flow channel distributed in the upper electrode plate, the cooling liquid flow channel having an inlet and an outlet, and connected to the cooling device through the cooling pipe, configured to allow a cooling liquid to flow from the cooling device through the inlet into the cooling liquid flow channel, and flow out through the outlet, and then return to the cooling device through the cooling pipe; a lower electrode plate having a gas input channel penetrating the upper electrode plate and configured to allow a process gas to flow through the upper electrode plate; and a cooling liquid flow channel disposed in the upper electrode plate. Below the upper electrode plate; an RF source configured to generate a bias between the upper electrode plate and the lower electrode plate; a flow sensor disposed in the cooling tube and located between the cooling device and the inlet of the cooling liquid flow channel, configured to obtain a flow value of the cooling liquid; and a relay, signal-connected to the flow sensor, configured to receive a signal about the flow value from the flow sensor, and disconnect a contact of the relay when the flow value exceeds a preset range, thereby cutting off a power supply of the plasma etching machine. A plasma etching machine as described in claim 4, wherein the preset range is between 2 liters per minute and 15 liters per minute. The plasma etching machine as described in claim 4, wherein the flow sensor further comprises an alarm, which is configured to send out an alarm signal when the flow value obtained by the flow sensor is greater than 15 liters per minute or less than 2 liters per minute. The plasma etching machine as described in claim 4 further comprises a controller disposed in the gas input channel of the upper electrode plate, and the signal is connected to the flow sensor, and the controller is configured to receive the signal about the flow value from the flow sensor and close the gas input channel according to the signal. A plasma etching machine as described in claim 7, wherein the controller is an electromagnetic valve.

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