WO2020228407A1

WO2020228407A1 - Charge transport apparatus and related plasma system

Info

Publication number: WO2020228407A1
Application number: PCT/CN2020/079535
Authority: WO
Inventors: 刘建; 韦刚
Original assignee: 北京北方华创微电子装备有限公司
Priority date: 2019-05-14
Filing date: 2020-03-16
Publication date: 2020-11-19
Also published as: CN111952231A; TW202109681A; TWI738250B

Abstract

Disclosed is a charge transport apparatus applied to a plasma system. The plasma system comprises a chamber and a lower electrode provided in the chamber, and the plasma system is used for processing a working piece placed on the lower electrode. The lower electrode comprises an electrode and a heater, wherein the electrode is used for generating, when the working piece is being processed, a suction force for fixing the working piece; and the heater is used for providing, when the working piece is being processed, a heat source for the working piece by means of an alternating-current power source and by means of an alternating-current voltage provided by a filtering apparatus coupled between the alternating-current power source and the heater. The charge transport apparatus is used for selectively transferring charges on a heater, and the charge transport apparatus comprises a first end point and a second end point, wherein the first end point is coupled between an alternating-current power source and the heater, and the second end point is coupled to a reference voltage end.

Description

Charge transfer device and related plasma system

Technical field

The present invention relates to a device, specifically, a charge transfer device and related plasma system.

Background technique

During wafer processing, electrostatic chucks are widely used to support, fix and cool the wafer. When processing the wafer, the electrostatic chuck will use a DC voltage to generate electrostatic attraction to the wafer to achieve a fixed effect. However, when the process is over, the residual charge on the electrostatic chuck will also affect the wafer The electrostatic adsorption force causes the sticking phenomenon, so that when the processed wafer is taken away, the electrostatic adsorption force will cause the wafer to shift and tilt, and even fail to take the wafer.

Summary of the invention

The present invention discloses a charge transfer device and a related plasma system to solve the problems in the background art, such as improper bonding of a wafer on an electrostatic chuck.

According to an embodiment of the present invention, a charge transfer device applied to a plasma system is disclosed. The plasma system includes a chamber and a lower electrode placed in the chamber, and the plasma system is configured to be opposed to The work piece on the lower electrode is processed, and the lower electrode includes an electrode and a heater, wherein the electrode is used to generate adsorption force to fix the work piece when the work piece is processed, and the heater is used for When the work piece is processed, a heat source is provided to the work piece through an AC power supply and an AC voltage provided by a filter device coupled between the AC power supply and the heater, and the charge transfer A device for selectively transferring the charge on the heater, the charge transfer device includes a first terminal and a second terminal, the first terminal is coupled between the AC power source and the heater , The second terminal is coupled to the reference voltage terminal.

According to an embodiment of the present invention, a plasma system including a chamber is disclosed. The plasma system is used to process a work piece placed in the chamber and includes an AC power supply, a filter device, a lower electrode, and Charge transfer device. The AC power supply is used to provide AC voltage. The filtering device is coupled to the AC power source and used to filter the AC voltage. The lower electrode is coupled to the AC power source and the filter device, and includes an electrode and a heater. The electrode is used to generate adsorption force when processing the work piece to fix the work piece. The heater is used for receiving the AC voltage filtered by the filtering device to provide a heat source. The charge transfer device is coupled to the heater and is used to selectively transfer the charge on the heater, and the charge transfer device includes a first terminal and a second terminal. The first terminal is coupled between the AC power source and the heater, and the second terminal is coupled to a reference voltage terminal.

Description of the drawings

FIG. 1 is a schematic diagram of a plasma system according to an embodiment of the invention.

2A is a schematic diagram of the lower electrode according to an embodiment of the invention.

2B is a schematic diagram of the ceramic layer in the lower electrode according to an embodiment of the invention.

2C is a schematic diagram of the heating layer in the lower electrode according to an embodiment of the invention.

FIG. 3 is a schematic diagram of a charge transfer device according to an embodiment of the invention.

4 is a schematic diagram of the operation of a charge transfer device according to an embodiment of the invention.

FIG. 5 is a schematic diagram of a plasma system according to another embodiment of the present invention.

Detailed ways

The following disclosure provides various embodiments or examples, which can be used to realize different features of the disclosure. The specific examples of components and configurations described below are used to simplify the present disclosure. When it is conceivable, these narratives are only examples and are not intended to limit the content of this disclosure. For example, in the following description, forming a first feature on or on a second feature may include some embodiments where the first and second features are in direct contact with each other; and may also include In some embodiments, additional components are formed between the above-mentioned first and second features, so that the first and second features may not be in direct contact. In addition, the present disclosure may reuse component symbols and/or labels in multiple embodiments. Such repeated use is based on the purpose of brevity and clarity, and does not in itself represent the relationship between the different embodiments and/or configurations discussed.

Furthermore, the use of spatially relative terms here, such as "below", "below", "below", "above", "above" and similar, may be used to facilitate the description of the drawing The relationship between one component or feature relative to another component or feature is shown. In addition to the orientation shown in the figure, these spatially relative terms also cover a variety of different orientations in which the device is in use or operation. The device may be placed in other orientations (for example, rotated by 90 degrees or in other orientations), and these spatially-relative description words should be explained accordingly.

Although the numerical ranges and parameters used to define the broader scope of the present application are approximate numerical values, the relevant numerical values in the specific embodiments have been presented here as accurately as possible. However, any value inherently inevitably contains the standard deviation due to individual test methods. Here, "about" usually means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range. Or, the word "about" means that the actual value falls within the acceptable standard error of the average value, depending on the consideration of a person with ordinary knowledge in the technical field to which this application belongs. It should be understood that all ranges, quantities, values and percentages used herein (for example, to describe the amount of material, time length, temperature, operating conditions, quantity ratio and other Similar ones) have been modified by "about". Therefore, unless otherwise stated to the contrary, the numerical parameters disclosed in this specification and the accompanying patent scope are approximate values and can be changed according to requirements. At least these numerical parameters should be understood as the indicated effective number of digits and the value obtained by applying the general carry method. Here, the numerical range is expressed from one end point to the other end point or between the two end points; unless otherwise specified, the numerical range described here includes the end points.

When the plasma system needs to process the work piece (such as wafer), for example, when the work piece (such as wafer) is etched, the work piece (such as wafer) will be placed in the plasma system through the robot arm On top of the lower electrode. The lower electrode usually has an electrostatic chuck. The plasma system will transmit a DC voltage of about one thousand to five thousand volts to the electrostatic chuck, and the DC voltage on the electrostatic chuck will cause electrostatic adsorption to the work piece (such as wafer) The force allows the work piece (such as wafer) to be fixed on the lower electrode during processing. When the processing is finished, the plasma system will perform de-chuck operation. In detail, the plasma system will transfer the reverse DC voltage to the electrostatic chuck to remove the charge in the lower electrode from the work piece ( Such as wafer) adsorption.

However, the desorption operation can only neutralize part of the charge, and the desorption operation is difficult to control. If the removal time is too long, reverse pressure may be generated. Therefore, as the mass production progresses, the internal charge of the electrostatic chuck continues to accumulate and the uneven distribution gradually becomes obvious, resulting in local work pieces (such as wafers) The attraction of the residual charge continues to increase. In this way, after the processing of the work piece (such as wafer) is completed, when the plasma system controls the ejector pin in the lower electrode to lift the work piece (such as wafer), it is easy to cause the work piece (such as wafer) to be attracted by the residual electric charge. (Wafer) deviation occurs, if it is serious, it will lead to failure in picking. The invention discloses a charge transfer device applied to a plasma system and a related plasma system to avoid possible offsets when taking out a work piece (such as a wafer) after processing is completed.

FIG. 1 is a schematic diagram of a plasma system 1 according to an embodiment of the invention. In this embodiment, the plasma system 1 is used to process a work piece (such as a wafer). For example, the plasma system 1 may be an etching device that uses plasma to process a work piece (such as a wafer). Etching. As shown in FIG. 1, the plasma system 1 includes a chamber 10, a lower electrode 11 placed in the chamber 10, an AC power supply 12, a filter device 13 and a charge transfer device 14. A work piece (such as a wafer) is placed on the lower electrode 11 for processing.

Referring to FIG. 2A, FIG. 2A is a schematic diagram of the lower electrode 11 according to an embodiment of the present invention. The lower electrode 11 may optionally include a ceramic layer 21, a heating layer 22, and a base 23. The ceramic layer 21 contains the aforementioned electrostatic chuck for fixing a work piece (such as a wafer) during processing; the heating layer 22 Used to control the temperature of work pieces (such as wafers). The susceptor 23 has a cooling liquid inside, which is used to implement temperature control of the work piece (such as a wafer) together with the heating layer 22, and one end of the susceptor 23 is grounded. The ceramic layer 21, the heating layer 22 and the base 23 are bonded with an adhesive. For example, the ceramic layer 21, the heating layer 22 and the base 23 are bonded with silica gel. Those skilled in the art should be able to easily understand that the components included in the lower electrode 11 are only examples and not a limitation of the present invention.

2B, FIG. 2B is a schematic diagram of a ceramic layer 21 according to an embodiment of the present invention. The ceramic layer 21 includes

ceramics

211 and 213 and electrodes 212. When the plasma system 1 transmits a DC voltage of one thousand to five thousand volts to the electrode 212, the electrode 212 generates electrostatic adsorption force to fix the work piece (such as a wafer). Referring to FIG. 2C, FIG. 2C is a schematic diagram of the heating layer 22 according to an embodiment of the present invention. The heating layer 22 includes a uniform heat plate 221, insulating

layers

222 and 224 and a heater 223. The uniform heat plate 221 is used to make the temperature distribution of the heating layer 22 more uniform. The heater 223 generates heat as a heat source under the action of AC voltage. The insulating

layers

222 and 224 are used as high-temperature resistant protective layers to avoid damage to other accessories or devices in the plasma system 1 when the heat generated by the heater 223 is too high. In some embodiments, the insulating

layers

222 and 224 include polyamide. In this embodiment, the uniform heat plate 221 and the insulating layer 222 are bonded with an adhesive. For example, the uniform heat plate 221 and the insulating layer 222 are bonded with silica gel.

During the processing of a work piece (such as a wafer), the electrode 212 is applied with a direct current voltage, and the direct current voltage is applied to each layer in the ceramic layer 21 (including the

ceramics

211 and 213 and the electrode 212) and each layer in the heating layer 22 ( The equivalent capacitance formed by the uniform heat plate 221, the insulating

layers

222 and 224, and the heater 223) is continuously charged, and different polarization voltages are generated between the layers, and there are polarization charges. Since the heating layer 22 uses more glue layers and thermal resistance resin materials, it has a larger thickness and a smaller capacitance. Correspondingly, the voltage division generated on the heater 223 is larger and the polarization charges are larger. Even if the removal and adsorption operation is performed at the end of processing, the polarized charges formed cannot be completely removed, which causes the aforementioned electrostatic adsorption force, which causes the risk of shifting of the ejector pin of the lower electrode 11 when the work piece (such as a wafer) is lifted. . The charge transfer device 14 disclosed in the present invention can effectively remove the residual charge and avoid the above situation.

Continuing to refer to FIG. 1, the AC power supply 12 is used to generate an AC voltage AC, and the filtered AC voltage AC′ is transmitted to the heater 223 through the filter device 13 coupled between the AC power supply 12 and the heater 223. 223 generates heat after receiving the alternating voltage AC'. The filter device 13 includes an inductor. Since the lower electrode 11 is in a radio frequency environment when the work piece (such as a wafer) is processed, the inductance inside the filter device 13 can filter the radio frequency electric field on the electrode 212, preventing the radio frequency electric field from interfering with the AC power supply 12 Voltage AC. The charge transfer device 14 is used to selectively transfer the charge on the heater 223. The charge transfer device 14 includes a first terminal N1 and a second terminal N2. The first terminal N1 can be coupled to the AC power supply 12 and the heater 223 between. In this embodiment, the first terminal N1 is coupled between the AC power source 12 and the filter device 13. The second terminal N2 is coupled to the reference voltage terminal 15. In this embodiment, the reference voltage terminal 15 is a ground terminal. Through the charge transfer device 14 to form a discharge path between the heater 223 and the ground terminal, the residual charge on the heater 223 can be effectively removed.

Those with ordinary knowledge in the art should be able to easily understand that the plasma system 1 should have other necessary devices and components to process work pieces (such as wafers). For example, the plasma system 1 should have an upper radio frequency power supply and a lower radio frequency power supply to excite the reaction gas in the chamber 10 into plasma to process a work piece (such as a wafer). For example, the lower electrode 11 also includes a thimble, which is used to control the raising of the thimble to lift the work piece (such as wafer) after the plasma system 1 finishes processing the work piece (such as wafer) to facilitate the robot arm to enter the chamber 10 Take out the work piece (such as wafer). For the sake of simplicity, FIG. 1 only depicts devices and components related to the spirit of the present invention.

FIG. 3 is a schematic diagram of a charge transfer device 14 according to an embodiment of the invention. The charge transfer device 14 includes an impedance 141 and a switch 142. The impedance 141 is coupled between the first terminal N1 and the second terminal N2. To be precise, one terminal of the impedance 141 is coupled to the first terminal through the switch 142 N1, and the other end of the impedance 141 is coupled to the second end N2. In this embodiment, the impedance 141 may be a resistance. The resistance value of the impedance 141 can be greater than a specific value, so that the AC current AC output by the AC power supply 12 will not be too large to cause damage to the device. In some embodiments, the resistance of the impedance 141 is greater than 200 kiloohms. In detail, after the processing of the work piece (such as a wafer) is completed, the electrode 212 cuts off the adsorption effect of the DC voltage. At this time, the switch 142 is activated, and the residual interlayer polarization charge on the heater 223 can pass through the charge transfer device The path composed of 14 leads directly to the ground. Therefore, through the activation of the switch 142, the charge transfer device 14 conducts the residual charge on the heater 223 to the reference voltage terminal 15 through the impedance 141, which greatly reduces the residual amount of polarized charge on the heater 223. Those skilled in the art should easily understand that whether the switch 142 is activated or not enables the charge transfer device 14 to selectively conduct the charge on the electrode 212 to the reference voltage terminal 15 through the impedance 141.

However, the activation timing of the switch 142 is not limited to the processing of the work piece (such as a wafer). For example, during the processing of a work piece (such as a wafer), the electrode 212 is loaded with a DC voltage for adsorption. At this time, the start switch 142 can also make the polarized charge on the heater 223 be at the negative phase voltage of the AC power supply 12. During this period, the path formed by the charge transfer device 14 is conducted to the reference voltage terminal 15.

It should be noted that in other embodiments, the charge transfer device 14 may not include the switch 142. As a result, during the processing of the work piece (such as a wafer) or after the processing of the work piece (such as a wafer) is completed, The charge transfer device 14 can conduct the polarized charge on the heater 223 to the reference voltage terminal 15 through the impedance 141.

4 is a schematic diagram of the operation of the charge transfer device 14 according to an embodiment of the invention. In the embodiment of FIG. 4, the switch 142 is in an activated state. In FIG. 4, the equivalent capacitance of the ceramic layer 21 is labeled C21, and the equivalent capacitances of the uniform heat plate 221, the insulating layer 222, and the heater 223 in the heating layer 22 are labeled C221, C222, and C223, respectively. By coupling the charge transfer device 14 between the heater 223 and the ground terminal, the insulating layer 224 at the bottom of the heater 223 and the glue layer capacitance between the heating layer 22 and the base 23 are located between the heater 223 and the grounding terminal. Between the bases 23, the insulating layer 224 and the adhesive layer capacitance between the heating layer 22 and the base 23 can be shielded. In other words, the overall equivalent thickness of the heating layer 22 becomes thinner. The equivalent capacitance of the heating layer 22 will only be formed by the series connection of the capacitance C221, the capacitance C222 and the capacitance C223, the equivalent capacitance of the heating layer 22 will therefore become larger, and the partial voltage received by the heating layer 22 will become smaller. As a result, during the processing of the work piece (such as a wafer), the polarized charge formed by the DC voltage applied by the electrode 212 to the heater 223 will be reduced. In addition, the charge transfer device 14 forms a discharge path between the heater 223 of the heating layer 22 and the ground terminal. As a result, after the processing of the work piece (such as a wafer) is completed, the electrode 212 cuts off the adsorption effect of the DC voltage. . At this time, the residual polarized charge on the heater 223 can be directly connected to the reference voltage terminal, preferably the ground terminal, through the path formed by the charge transfer device 14. And as shown in the embodiment in FIG. 3, not only after the processing is completed, but also when the work piece (such as a wafer) is being processed, the polarized charge on the heater 223 can also pass the charge during the negative phase voltage of the AC power supply 12. The path formed by the transmission device 14 is conducted to the ground terminal.

Those with ordinary knowledge in the field should be able to easily understand after reading the above paragraphs, as long as a discharge path can be formed between the heater 223 and the ground terminal, the charge transfer device 14 is not limited to being coupled to the AC voltage 12 and the filter. Between devices 13. FIG. 5 is a schematic diagram of a plasma system 5 according to another embodiment of the invention. As in the embodiment of FIG. 1, the plasma system 5 is used to process a work piece (such as a wafer). For example, the plasma system 5 may be an etching device that uses plasma to process a work piece (such as a wafer). ) Perform etching. As shown in FIG. 5, the plasma system 5 includes a chamber 50, a lower electrode 51 placed in the chamber 50, an AC power supply 52, a filter device 53 and a charge transfer device 54. A work piece (such as a wafer) is placed on the lower electrode 51 for processing. The plasma system 5 shown in FIG. 5 is roughly the same as the plasma system 1, the only difference is that the charge transfer device 54 includes a first terminal N1' and a second terminal N2', wherein the first terminal N1' is coupled to the filter device Between 53 and the heater 523 of the lower electrode 51, the second terminal N2 ′ is coupled to the reference voltage terminal 55. Similarly, in this embodiment, the reference voltage terminal 55 is a ground terminal. Those with ordinary knowledge in the art should be able to easily understand how the charge transfer device 54 forms a discharge path between the heater 523 and the ground terminal to remove residual charges after reading the above paragraphs. The detailed description is omitted here to save space.

Summarizing the present invention simply, the present invention discloses a charge transfer device and related plasma system. The charge transfer device disclosed in the present invention can effectively shield the insulating layer at the bottom of the heater and the glue layer between the heating layer and the base. Capacitance, in other words, the overall equivalent thickness of the heating layer becomes thinner, and the equivalent capacitance of the heating layer becomes larger, and the partial pressure received by the heating layer becomes smaller. As a result, during the processing of the work piece (such as a wafer), the polarized charge formed by the DC voltage applied by the electrode to the heater will be reduced. In addition, the charge transfer device disclosed in the present invention is used to form a discharge path between the heater and the ground terminal. In this way, the polarized charge on the heater can be directly connected to the ground through the path formed by the charge transfer device. Effectively reduce the risk of offset when the ejector pin of the lower electrode lifts the work piece (such as a wafer).

Claims

A charge transfer device applied to a plasma system. The plasma system includes a chamber and a lower electrode placed in the chamber. The plasma system is used to perform processing on a work piece placed on the lower electrode. For processing, the lower electrode includes an electrode and a heater, wherein the electrode is used to generate an adsorption force to fix the work piece when the work piece is processed, and the heater is used when the work piece is processed , The heat source is provided to the workpiece through the AC power supply and the AC voltage provided by the filter device coupled between the AC power supply and the heater, wherein the charge transfer device is used for selective Ground transfer of the electric charge on the heater, the charge transfer device includes a first terminal and a second terminal, the first terminal is coupled between the AC power source and the heater, the second The terminal is coupled to the reference voltage terminal.
The charge transfer device of claim 1, further comprising:

The resistor is coupled between the first terminal and the second terminal.
The charge transfer device of claim 2, further comprising:

A switch is coupled between the first terminal and the resistor. When the switch is activated, the charge transfer device transfers the charge on the heater to the reference voltage terminal.
8. The charge transfer device of claim 1, wherein the first terminal is coupled between the heater and the filter device.
8. The charge transfer device of claim 1, wherein the first terminal is coupled between the AC power source and the filter device.
A plasma system including a chamber is characterized in that it is used to process a work piece placed in the chamber and includes:

AC power supply, used to provide AC voltage;

A filter device, coupled to the AC power source, for filtering the AC voltage;

The lower electrode, coupled to the AC power supply and the filter device, includes:

An electrode, wherein the electrode is used to generate adsorption force when processing the work piece to fix the work piece; and

A heater for receiving the AC voltage filtered by the filtering device to provide a heat source; and

A charge transfer device, coupled to the heater, for selectively transferring the charge on the heater, the charge transfer device includes a first terminal and a second terminal, the first terminal is coupled to Between the AC power supply and the heater, the second terminal is coupled to a reference voltage terminal.
7. The plasma system of claim 6, wherein said charge transfer device further comprises:

The resistor is coupled between the first terminal and the second terminal.
8. The plasma system of claim 7, wherein the charge transfer device further comprises:

A switch is coupled between the first terminal and the resistor. When the switch is activated, the charge transfer device transfers the charge on the heater to the reference voltage terminal.
7. The plasma system of claim 6, wherein the first terminal is coupled between the heater and the filter device.
7. The plasma system of claim 6, wherein the first terminal is coupled between the AC power source and the filter device.