CN112345814A - DC bias detection method, device, jig and lower electrode system - Google Patents

DC bias detection method, device, jig and lower electrode system Download PDF

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CN112345814A
CN112345814A CN202011194899.7A CN202011194899A CN112345814A CN 112345814 A CN112345814 A CN 112345814A CN 202011194899 A CN202011194899 A CN 202011194899A CN 112345814 A CN112345814 A CN 112345814A
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bias
peak voltage
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张璐
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Beijing Naura Microelectronics Equipment Co Ltd
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Beijing Naura Microelectronics Equipment Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/04—Measuring peak values or amplitude or envelope of ac or of pulses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/244—Detectors; Associated components or circuits therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32532—Electrodes

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  • Testing Or Measuring Of Semiconductors Or The Like (AREA)

Abstract

The embodiment of the invention provides a direct current bias voltage detection method, a direct current bias voltage detection device, a jig and a lower electrode system. The method comprises the following steps: adjusting the impedance of a radio frequency path formed between the output end of the matcher electrically connected with the tested component and the tested component so as to enable the variation trend of the first peak voltage to be consistent with that of the second peak voltage; the peak value of the alternating voltage output by a matcher electrically connected with a tested component is the first peak voltage, and the peak value of the alternating voltage at the tested component is the second peak voltage; detecting the actual value of the first peak voltage in real time when a process chamber where the detected component is located is processed; and calculating to obtain the actual value of the direct current bias voltage according to the prestored actual value of the first peak voltage and the corresponding relation between the direct current bias voltage and the first peak voltage. The direct current bias voltage detection method, the direct current bias voltage detection device, the jig and the lower electrode system provided by the embodiment of the invention can accurately detect the direct current bias voltage of the detected component in real time.

Description

DC bias detection method, device, jig and lower electrode system
Technical Field
The invention relates to the technical field of semiconductor processing, in particular to a direct current bias voltage detection method, a direct current bias voltage detection device, a direct current bias voltage detection jig and a lower electrode system.
Background
In plasma etching or deposition systems, a radio frequency power supply is typically used to power a process chamber to generate a plasma. The plasma contains a large number of reactive species, such as electrons, ions, excited atoms, molecules, and radicals, which interact with the wafer disposed in the process chamber and exposed to the plasma environment to cause various physical and chemical reactions to occur on the surface of the wafer material, thereby completing the etching, deposition, or other processes of the wafer.
In a plasma environment, a dc negative bias is formed on the wafer surface. This dc bias attracts the positively charged ions and reactive radicals in the plasma to accelerate toward the wafer surface and act on the wafer surface to achieve the desired process results. The magnitude of the dc bias voltage affects the bombardment energy of the positive ions and, in turn, the associated process parameters (e.g., etch rate, deposition rate, etc.). Currently, an rf power source is usually used to apply an rf signal to the bottom electrode through a matching unit to form a dc negative bias on the wafer surface. However, the fluctuations of the RF signal applied to the bottom electrode may cause fluctuations of the DC negative bias on the wafer, which may affect the stability of the process, and therefore, the DC bias needs to be monitored.
However, at present, it is impossible to monitor the dc bias accurately and in real time.
Disclosure of Invention
The embodiment of the invention aims to solve at least one technical problem in the prior art, and provides a direct current bias voltage detection method, a device, a jig and a lower electrode system, which are used for accurately detecting the direct current bias voltage of a detected component in real time.
In order to achieve the above object, an embodiment of the present invention provides a dc bias detection method for detecting a dc bias value of a device under test in a process chamber, including:
adjusting impedance of a radio frequency path formed between an output end of a matcher electrically connected with a tested component and the tested component so as to enable variation trends of a first peak voltage and a second peak voltage to be consistent, wherein the first peak voltage is a peak value of alternating current voltage output by the matcher electrically connected with the tested component, and the second peak voltage is a peak value of the alternating current voltage at the tested component;
detecting the actual value of the first peak voltage in real time when a process chamber where the tested part is located is processed;
and calculating in real time to obtain the actual value of the direct current bias voltage according to the prestored actual value of the first peak voltage and the corresponding relation between the direct current bias voltage and the first peak voltage.
Optionally, the adjusting the impedance of the radio frequency path formed between the output end of the matcher electrically connected to the component to be tested and the component to be tested specifically includes:
and adjusting the capacitance value of a variable capacitor and/or the inductance value of a variable inductor arranged on the radio frequency path so as to enable the impedance of the radio frequency path to approach zero.
Optionally, the adjusting the impedance of the radio frequency path formed between the output end of the matcher electrically connected to the component to be tested and the component to be tested specifically includes:
and adjusting the distributed capacitance and the distributed inductance on the radio frequency path to enable the impedance of the radio frequency path to approach zero.
Optionally, the method for adjusting the distributed capacitance and the distributed inductance specifically includes:
adjusting the length of the radio frequency path; and/or adjusting the distance between the radio frequency power supply and the ground; and/or different dielectric materials are arranged between the radio frequency power supply and the ground, wherein the radio frequency power supply is electrically connected with the matcher.
Optionally, the method for obtaining the corresponding relationship between the dc bias voltage on the measured component and the first peak voltage specifically includes:
the process chamber carries out a process under preset process parameters, and detection values of the direct current bias voltages and the first peak voltage values which correspond to the set values of the preset process parameters one to one are obtained through detection in the process;
and fitting according to the detection value of each direct current bias voltage and the detection value of each first peak voltage to obtain the corresponding relation between the direct current bias voltage and the first peak voltage.
Optionally, the fitting according to the detected value of each dc bias voltage and the detected value of each first peak voltage to obtain the corresponding relationship between the dc bias voltage and the first peak voltage specifically includes:
obtaining the following functional relation between the DC bias voltage and the first peak voltage by adopting a linear fitting mode:
V0＝aV1+b
wherein, V0Biasing the DC bias voltage; v1Is the first peak voltage; a. and b is a fitting coefficient.
As another technical solution, an embodiment of the present invention further provides a dc bias detection apparatus, including:
the impedance adjusting element is arranged on a radio frequency path formed between the output end of the matcher electrically connected with the tested component and the tested component;
the controller is electrically connected with the impedance adjusting element and is used for controlling the impedance adjusting element to adjust the impedance of the radio frequency channel so as to enable the variation trend of a first peak voltage and a second peak voltage to be consistent, wherein the first peak voltage is the peak value of alternating current voltage output by a matcher electrically connected with a tested component, and the second peak voltage is the peak value of the alternating current voltage at the tested component;
the memory is used for storing the corresponding relation between the direct current bias voltage on the tested component and the first peak voltage;
the peak voltage detection element is arranged at the output end of the matcher and used for detecting the actual value of the first peak voltage in real time when a process chamber where the detected part is located is used for carrying out a process;
the controller is further configured to calculate in real time to obtain an actual value of the dc bias voltage according to the actual value of the first peak voltage and a corresponding relationship between the dc bias voltage and the first peak voltage.
Optionally, the impedance adjusting element comprises a variable capacitance and/or a variable inductance.
As another technical solution, an embodiment of the present invention further provides a dc bias detection fixture, which is applied to the dc bias detection method provided in the embodiment of the present invention, and the dc bias detection fixture includes a probe and a voltage reading device, where the probe has a detection end and an output end, where the detection end is used to electrically contact the component to be detected in the process chamber during a process, and is used to detect and obtain detection values of the dc biases corresponding to the respective set values of the preset process parameters one to one; the output end is electrically connected with the voltage reading device.
Optionally, the probe comprises a housing, a voltage dividing element arranged in the housing, and an adapter structure arranged outside the housing; wherein the voltage dividing element has a first lead and a second lead, wherein one end of the first lead serves as the detection end and extends to the outside of the case; one end of the second lead is used as the output end to be electrically connected with the switching structure; the switching structure is used for leading the second lead out of the process chamber and is electrically connected with the voltage reading device.
Optionally, the adapting structure includes a first adapter, a second adapter, and a shielding wire, where the first adapter is disposed on the housing; the second adapter is electrically connected with the voltage reading device and is used for being installed on the outer wall of the process chamber; one end of the shielding wire is electrically connected with the first adapter, and the other end of the shielding wire is electrically connected with the second adapter; an insulating layer is coated on the shield wire.
Optionally, the probe further comprises an insulating part and an insulating medium layer, wherein the insulating part is arranged in the casing and covers the part of the first lead wire in the casing and at least covers the connection part of the first lead wire and the voltage dividing element; the insulating medium layer covers the outer surface of the shell.
As another technical solution, an embodiment of the present invention further provides a bottom electrode system, which includes a susceptor disposed in a process chamber, a matcher electrically connected to the susceptor, and a dc bias detection device for detecting a dc bias of a wafer disposed on the susceptor, where the dc bias detection device employs the dc bias detection device provided in the embodiment of the present invention.
The embodiment of the invention has the following beneficial effects:
in the technical solution of the dc bias detection method and apparatus provided in the embodiments of the present invention, according to a pre-stored correspondence between a dc bias on a measured component and a first peak voltage (a peak value of an ac voltage output by a matcher electrically connected to the measured component), the dc bias on the measured component can be represented by using the first peak voltage, that is, when a process chamber in which the measured component is located is used for a process, an actual value of the first peak voltage is detected in real time, and an actual value of the dc bias is obtained by calculating in real time according to the actual value and the correspondence. Therefore, the direct current bias voltage of the tested component can be accurately detected in real time, so that the direct current bias voltage can be controlled within a set range, and the process stability can be improved.
The direct current bias detection jig provided by the embodiment of the invention is applied to the direct current bias detection method provided by the embodiment of the invention, and can realize accurate and real-time detection of the direct current bias of the detected component, so that the direct current bias can be controlled within a set range, and the process stability can be further improved.
By adopting the direct current bias detection device provided by the embodiment of the invention, the direct current bias of the detected component can be accurately detected in real time, so that the direct current bias can be controlled within a set range, and the process stability can be improved.
Drawings
FIG. 1A is a schematic diagram of a conventional bottom electrode system;
FIG. 1B is an equivalent circuit diagram of a conventional RF path;
FIG. 2 is a block diagram of a DC bias detection method according to an embodiment of the present invention;
FIG. 3 is a graph showing the relationship between the absolute value of the DC bias voltage applied to the device under test and the peak voltage of the AC voltage output from the matching unit;
FIG. 4 is a graph of a fit in an embodiment of the invention;
FIG. 5 is a schematic block diagram of a DC bias detection apparatus according to an embodiment of the present invention;
FIG. 6 is a block diagram of a lower electrode system provided in accordance with an embodiment of the present invention;
fig. 7 is a structural diagram of a probe of the dc bias detection fixture in the embodiment of the invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the dc bias detection method, apparatus, fixture and bottom electrode system provided in the embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Referring to fig. 1A, the conventional bottom electrode system includes a susceptor 71 disposed in a process chamber 7 for carrying a wafer; the base 71 is electrically connected to the matching unit 5 through a shield 72, and the matching unit 5 is electrically connected to the radio frequency power supply 8. The RF power source 8 applies an RF signal to the susceptor 71 through the matcher 5 to form a DC bias on the wafer 4. In addition, two variable devices (usually, variable capacitors) 52 and 53 are provided inside the matching unit 5 to ensure the maximum power output of the rf power supply 8.
The wafer placed on the susceptor 71 serves as the part 4 to be measured, and the dc bias voltage thereon needs to be monitored in real time while the process chamber 7 is performing the process to be controlled within a set range, thereby ensuring process stability. In the conventional method for detecting the dc bias, a dc detection module 51 is installed at an output terminal of the matcher 5 for detecting the dc voltage. However, in practical application, there is a problem that Vdc is an rf bias voltage on the wafer, as shown in fig. 1B, between the rf bias voltage Vdc and the detection position of the dc detection module 51Presence of a capacitance CdAnd a capacitor CdsThe presence of the two will make the dc bias voltage detected by the dc detecting module 51 smaller than the actual value of the rf bias voltage on the wafer, and the dc bias voltage detected by different wafers will be different, so that the dc detecting module 51 cannot accurately detect the dc bias voltage on the wafer.
In order to solve the above problem, as shown in fig. 2, an embodiment of the present invention provides a dc bias detection method, which includes the following steps:
s1, adjusting the impedance of a radio frequency path formed between the output end of the matcher electrically connected with the tested component and the tested component so as to enable the variation trends of the first peak voltage and the second peak voltage to be consistent; the first peak voltage is a peak value of an ac voltage output from a matching device electrically connected to the component to be measured, and the second peak voltage is a peak value of an ac voltage at the component to be measured.
The peak value of the ac voltage is a maximum value of the instantaneous voltage.
The consistent trend of the changes means that the first peak voltage and the second peak voltage have a corresponding relationship in changes, so that the first peak voltage and the second peak voltage can be mutually characterized.
S2, detecting the actual value of the first peak voltage in real time when the process chamber where the tested part is located is processed;
and S3, calculating in real time to obtain the actual value of the direct current bias voltage according to the prestored actual value of the first peak voltage and the corresponding relation between the direct current bias voltage and the first peak voltage.
The component to be measured may be, for example, a wafer, or may be any component in a process chamber.
In the plasma environment of a process chamber, alternating current on the surface of a component under test (e.g., a wafer) in the rf path attracts electrons at positive voltages and ions at negative voltages, which eventually form a dc bias on the surface of the component under test over time due to the much higher electron mobility than ion mobility. In this process, the larger the second peak voltage on the device under test, the larger the number of electrons attracted per unit time, and thus the larger the absolute value of the dc bias voltage on the device under test. Therefore, the absolute value of the direct current bias voltage on the tested component and the magnitude change trend of the second peak voltage are the same, namely, the absolute value of the direct current bias voltage on the tested component and the magnitude change trend of the second peak voltage are in a corresponding relation, so that the direct current bias voltage can be represented by the second peak voltage on the tested component, and the direct current bias voltage can be obtained through calculation according to the corresponding relation by detecting the second peak voltage.
However, when a normal process is performed, the second peak voltage cannot be directly obtained from the measured component in the process chamber in real time, but only the peak voltage output by the matching device located outside the process chamber can be detected in real time, which causes a problem that the impedance of the rf path is large due to a distribution parameter (which may be equivalent to a distributed inductance or a distributed capacitance) existing on the rf path formed between the matching device and the measured component, which is relatively far from the measured component, and thus the absolute value of the dc bias and the variation trend of the peak voltage output by the matching device are inconsistent, for example, as shown in fig. 3, the variation curve of the absolute value of the dc bias has a monotonous decreasing trend, and the variation curve of the peak voltage output by the matching device has an inflection point. Therefore, in step S1, by adjusting the impedance of the rf path, the first peak voltage and the second peak voltage may be made to coincide with each other, that is, the first peak voltage and the second peak voltage may have a correspondence relationship with each other, so that the dc bias voltage on the device under test may be characterized by using the first peak voltage.
Therefore, when the process chamber where the tested part is located is used for carrying out the process, the actual value of the first peak voltage is detected in real time, and the actual value of the direct current bias voltage is obtained through real-time calculation according to the actual value and the corresponding relation between the first peak voltage and the direct current bias voltage, so that the direct current bias voltage of the tested part can be accurately detected in real time, the direct current bias voltage can be controlled within a set range, and the process stability can be improved.
In the step S1, there may be a plurality of ways to adjust the impedance of the rf path, for example, the step S1 specifically includes:
the capacitance value of the variable capacitor and/or the inductance value of the variable inductor arranged on the radio frequency path are adjusted so as to enable the impedance of the radio frequency path to approach zero.
Taking the example of arranging the variable capacitor on the radio frequency path, the capacitance value of the variable capacitor is adjusted to realize series resonance with the distributed inductance on the radio frequency path, and at the moment, the total impedance on the radio frequency path is minimum, so that the change trends of the first peak voltage and the second peak voltage tend to be consistent. Of course, in practical applications, a variable inductor may be provided in the rf path, or both a variable capacitor and a variable inductor may be provided.
For another example, step S1 further includes:
the distributed capacitance and distributed inductance on the radio frequency path are adjusted so that the impedance of the radio frequency path approaches zero.
In some embodiments, the method for adjusting distributed capacitance and distributed inductance specifically includes:
adjusting the length of the radio frequency path; and/or adjusting the distance between the radio frequency power supply (electrically connected with the matcher) and the ground; and/or different dielectric materials are arranged between the radio frequency power supply and the ground.
When the variation trends of the first peak voltage and the second peak voltage are consistent, the absolute value of the dc bias voltage is also consistent with the variation trend of the first peak voltage, and there are many ways to obtain the corresponding relationship, for example, the dc bias voltage of the tested component can be directly detected by a dedicated dc bias voltage detection jig, and the corresponding relationship can be obtained by calculation, and the corresponding relationship is stored in advance before the formal process is performed.
For example, the method for acquiring the correspondence relationship specifically includes:
step 101, performing a process under a preset process parameter by using a process chamber, and detecting and obtaining detection values of each dc bias voltage and each first peak voltage corresponding to each set value of the preset process parameter one to one in the process.
The preset process parameters include, for example, upper electrode power, lower electrode power, chamber pressure, etc.
Taking the preset process parameters including the upper electrode power and the lower electrode power as an example, the following table 1 shows the detected values of the dc biases corresponding to the set values of the preset process parameters (the upper electrode power Source and the lower electrode power Bias) obtained by detection. Table 2 below shows detected values of the first peak voltages, which correspond to the respective set values of the preset process parameters (the upper electrode power Source and the lower electrode power Bias) obtained by detection one to one.
Table 1 shows the detected values of the dc bias.
Figure BDA0002753749640000081
Table 2 shows the detected value of the first peak voltage.
Figure BDA0002753749640000082
Figure BDA0002753749640000091
And 102, fitting according to the detection values of the direct current bias voltages and the detection values of the first peak voltages to obtain the corresponding relation between the direct current bias voltages and the first peak voltages.
In the step 102, there may be a plurality of fitting methods, and for example, the step 102 specifically includes:
obtaining the following functional relation between the DC bias voltage and the first peak voltage by adopting a linear fitting mode:
V0＝aV1+b
wherein, V0Is a DC bias voltage; v1Is a first peak voltage; a. and b is a fitting coefficient.
By substituting the detected values of the dc bias voltages and the first peak voltages in tables 1 and 2 into the functional relation, fitting coefficients a and b can be calculated as:
a＝-0.8532，b＝-35.908；
thereby, a fitted straight line as shown in fig. 4, i.e. a straight-line functional relationship between the dc bias and the first peak voltage, may be obtained.
It should be noted that the corresponding relationship between the dc bias and the first peak voltage is obtained in an off-line manner, and by storing the corresponding relationship in advance, the corresponding relationship can be directly called when a formal process is performed, so that online monitoring of the dc bias can be realized.
In summary, according to the dc bias detection method provided in the embodiment of the present invention, the pre-stored corresponding relationship between the dc bias on the tested component and the first peak voltage (the peak value of the ac voltage output by the matcher electrically connected to the tested component) can be used to characterize the dc bias on the tested component by using the first peak voltage, that is, when the process chamber where the tested component is located performs a process, the actual value of the first peak voltage is detected in real time, and the actual value of the dc bias is obtained by calculating in real time according to the actual value and the corresponding relationship. Therefore, the direct current bias voltage of the tested component can be accurately detected in real time, so that the direct current bias voltage can be controlled within a set range, and the process stability can be improved.
As another technical solution, referring to fig. 5, an embodiment of the present invention further provides a dc bias detection apparatus, which includes an impedance adjusting element 1, a memory 13, a peak voltage detecting element 2, and a controller 3, wherein the impedance adjusting element 1 is disposed on a radio frequency path 6 formed between an output end of a matcher 5 electrically connected to a tested component 4 and the tested component 4, and is configured to adjust an impedance of the radio frequency path 6;
the memory 13 is used for storing the corresponding relation between the dc bias voltage on the tested component 4 and the first peak voltage. The first peak voltage is a peak value of the ac voltage output from the matching unit 5 electrically connected to the device under test 4, and the second peak voltage is a peak value of the ac voltage at the device under test 4. The memory 13 is, for example, an upper computer or a memory element in the matching unit 5.
The peak voltage detecting element 2 is disposed at an output end of the matcher 5, and is configured to detect an actual value of the first peak voltage in real time when a process is performed in a process chamber in which the component 4 to be detected is located.
The controller 3 is electrically connected with the impedance adjusting element 1 and is used for controlling the impedance adjusting element 1 to adjust the impedance of the radio frequency path 6 so as to enable the variation trend of the first peak voltage to be consistent with that of the second peak voltage; and the controller is also used for calculating in real time to obtain the actual value of the direct current bias voltage according to the actual value of the first peak voltage and the corresponding relation between the direct current bias voltage and the first peak voltage.
In the present embodiment, as shown in fig. 6, the impedance adjusting element 1 is disposed on the rf path 6, specifically between the shield 72 and the output end of the matching unit 5, and is used for adjusting the impedance of the rf path 6 formed between the output end of the matching unit 5 and the tested component 4, so as to make the variation trends of the first peak voltage and the second peak voltage consistent. The impedance adjusting element 1 comprises, for example, a variable capacitance and/or a variable inductance arranged in the radio frequency path to cause the impedance of the radio frequency path 6 to approach zero.
In summary, the dc bias detection apparatus provided in the embodiment of the present invention can use the first peak voltage to characterize the dc bias on the tested component through the pre-stored corresponding relationship between the dc bias on the tested component and the first peak voltage (the peak value of the ac voltage output by the matcher electrically connected to the tested component), that is, when the process chamber where the tested component is located is performing a process, the actual value of the first peak voltage is detected in real time, and the actual value of the dc bias is obtained through real-time calculation according to the actual value and the corresponding relationship. Therefore, the direct current bias voltage of the tested component can be accurately detected in real time, so that the direct current bias voltage can be controlled within a set range, and the process stability can be improved.
As described above, when the variation trends of the first peak voltage and the second peak voltage are the same, the absolute value of the dc bias voltage is also the same as the variation trend of the first peak voltage, and there are many ways to obtain the corresponding relationship, for example, a dedicated dc bias voltage detection jig 12 may be used to directly detect the dc bias voltage of the component 4 to be tested, and the corresponding relationship may be obtained by calculation, and the corresponding relationship may be stored in advance before performing a formal process.
Based on this, as another technical solution, as shown in fig. 7, an embodiment of the present invention further provides a dc bias detection fixture 12, which is applied to the dc bias detection method provided in the embodiment of the present invention, and is specifically configured to electrically contact the tested component 4 when the process chamber 7 is used for performing a process under a preset process parameter, and detect and obtain detection values of the dc biases corresponding to respective set values of the preset process parameter one to one in a process.
Meanwhile, when the process is carried out under the preset process parameters, the peak voltage detection element 2 is used for detecting and obtaining the detection value of each first peak voltage, and then the corresponding relation between the direct current bias voltage and the first peak voltage is obtained through fitting according to the detection value of each direct current bias voltage and the detection value of each first peak voltage.
The following describes the specific structure of the dc bias detection tool 12 according to the embodiment of the present invention in detail. Specifically, the dc bias detection jig 12 includes a probe having a detection end for electrically contacting the component 4 to be measured (for example, a wafer disposed on the susceptor 71) at the time of performing the process, for detecting and obtaining detection values of respective dc biases corresponding one-to-one to respective set values of preset process parameters, and an output end, specifically, attached to the surface of the component 4 to be measured, for example, with a conductive adhesive, to maintain the electrical contact; the output terminal is electrically connected to a voltage reading device (not shown). The voltage reading device is used for reading the detection values of the direct current bias voltages obtained by the detection of the probe.
In the present embodiment, as shown in fig. 7, the probe of the dc bias detection fixture 12 includes, for example, a housing 121, a voltage dividing element 122 (for example, a resistor with a higher resistance value) disposed in the housing 121, and an adapting structure 123 disposed outside the housing 121; wherein the voltage dividing element 122 has a first lead 122a and a second lead 122b, wherein one end of the first lead 122a is used as the above-mentioned detection end and extends to the outside of the casing 121 so as to be able to electrically contact with the component 4 to be detected; one end of the second lead 122b is used as the output end to be electrically connected to the adapting structure 123; the adapting structure 123 is used for leading the second lead 122b out of the process chamber 7 and electrically connecting with the voltage reading device.
The structure of the adapting structure 123 may be various, for example, as shown in fig. 7, the adapting structure 123 includes a first adapter 123a, a second adapter 123b and a shielding wire 123c, wherein the first adapter 123a is disposed on the housing 121; the second adapter 123b is electrically connected to the voltage reading device and is configured to be mounted on the outer wall of the process chamber 7; one end of the shielding wire 123c is electrically connected to the first adapter 123a, and the other end of the shielding wire 123c is electrically connected to the second adapter 123 b; an insulating layer 123d is coated on the second adapter 123 b. The insulating layer 123d may be selected to completely or partially cover the second adapter 123b according to specific situations.
In this embodiment, the probe further includes an insulating member 124 and an insulating medium layer 125, wherein the insulating member 124 is disposed in the casing 121 and covers a portion of the first lead 122a located in the casing 121 and at least a connection portion of the first lead 122a and the voltage dividing element 122, so as to prevent the first lead 122a from being ignited between high voltage and the casing 121. An insulating dielectric layer 125 covers the outer surface of the housing 121. In addition, the housing 121 may be made of a metal material and grounded to reduce the bombardment of plasma.
The dc bias detection jig 12 is used to detect the detection value of each dc bias in a test process performed in advance to obtain the correspondence relationship before the normal process is performed, and is not used when the main process is performed.
As another technical solution, an embodiment of the present invention further provides a bottom electrode system, as shown in fig. 6, which includes a pedestal 71 disposed in a process chamber 7, an adapter 5 electrically connected to the pedestal 71, and a dc bias detection device for detecting a dc bias of a wafer (i.e., a device under test 4) placed on the pedestal 71, wherein the dc bias detection device employs the above-mentioned dc bias detection device provided in the embodiment of the present invention.
By adopting the direct current bias detection device provided by the embodiment of the invention, the direct current bias of the detected component can be accurately detected in real time, so that the direct current bias can be controlled within a set range, and the process stability can be improved.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims (13)

1. A DC bias detection method for detecting a DC bias value of a tested part in a process chamber during a process, comprising:
adjusting impedance of a radio frequency path formed between an output end of a matcher electrically connected with a tested component and the tested component so as to enable variation trends of a first peak voltage and a second peak voltage to be consistent, wherein the first peak voltage is a peak value of alternating current voltage output by the matcher electrically connected with the tested component, and the second peak voltage is a peak value of the alternating current voltage at the tested component;
detecting the actual value of the first peak voltage in real time when a process chamber where the tested part is located is processed;
and calculating in real time to obtain the actual value of the direct current bias voltage according to the prestored actual value of the first peak voltage and the corresponding relation between the direct current bias voltage and the first peak voltage.
2. The method according to claim 1, wherein the adjusting the impedance of the rf path formed between the output terminal of the matcher electrically connected to the device under test and the device under test specifically comprises:
and adjusting the capacitance value of a variable capacitor and/or the inductance value of a variable inductor arranged on the radio frequency path so as to enable the impedance of the radio frequency path to approach zero.
3. The method according to claim 1 or 2, wherein the adjusting of the impedance of the rf path formed between the output terminal of the matcher electrically connected to the device under test and the device under test further comprises:
and adjusting the distributed capacitance and the distributed inductance on the radio frequency path to enable the impedance of the radio frequency path to approach zero.
4. The method according to claim 3, wherein the method for adjusting the distributed capacitance and the distributed inductance comprises:
adjusting the length of the radio frequency path; and/or adjusting the distance between the radio frequency power supply and the ground; and/or different dielectric materials are arranged between the radio frequency power supply and the ground, wherein the radio frequency power supply is electrically connected with the matcher.
5. The method according to claim 1, wherein the method for obtaining the correspondence between the dc bias voltage on the device under test and the first peak voltage specifically comprises:
the process chamber carries out a process under preset process parameters, and detection values of the direct current bias voltages and the first peak voltage values which correspond to the set values of the preset process parameters one to one are obtained through detection in the process;
and fitting according to the detection value of each direct current bias voltage and the detection value of each first peak voltage to obtain the corresponding relation between the direct current bias voltage and the first peak voltage.
6. The method according to claim 5, wherein the fitting of the corresponding relationship between the dc bias voltage and the first peak voltage according to the detected value of each dc bias voltage and the detected value of each first peak voltage specifically comprises:
obtaining the following functional relation between the DC bias voltage and the first peak voltage by adopting a linear fitting mode:
V0＝aV1+b
wherein, V0Biasing the DC bias voltage; v1Is the first peak voltage; a. and b is a fitting coefficient.
7. A dc bias voltage detection device, comprising:
the impedance adjusting element is arranged on a radio frequency path formed between the output end of the matcher electrically connected with the tested component and the tested component;
the controller is electrically connected with the impedance adjusting element and is used for controlling the impedance adjusting element to adjust the impedance of the radio frequency channel so as to enable the variation trend of a first peak voltage and a second peak voltage to be consistent, wherein the first peak voltage is the peak value of alternating current voltage output by a matcher electrically connected with a tested component, and the second peak voltage is the peak value of the alternating current voltage at the tested component;
the memory is used for storing the corresponding relation between the direct current bias voltage on the tested component and the first peak voltage;
the peak voltage detection element is arranged at the output end of the matcher and used for detecting the actual value of the first peak voltage in real time when a process chamber where the detected part is located is used for carrying out a process;
the controller is further configured to calculate in real time to obtain an actual value of the dc bias voltage according to the actual value of the first peak voltage and a corresponding relationship between the dc bias voltage and the first peak voltage.
8. The dc bias voltage detection device according to claim 7, wherein the impedance adjustment element comprises a variable capacitor and/or a variable inductor.
9. A dc bias detection fixture, applied to the dc bias detection method according to claim 5 or 6, wherein the dc bias detection fixture comprises a probe and a voltage reading device, wherein the probe has a detection end and an output end, wherein the detection end is used for electrically contacting the component to be detected in the process chamber during the process, and is used for detecting and obtaining detection values of the dc biases corresponding to the set values of the preset process parameters one to one; the output end is electrically connected with the voltage reading device.
10. The dc bias voltage detection jig of claim 9, wherein the probe comprises a housing, a voltage dividing element disposed in the housing, and an adapting structure disposed outside the housing; wherein the voltage dividing element has a first lead and a second lead, wherein one end of the first lead serves as the detection end and extends to the outside of the case; one end of the second lead is used as the output end to be electrically connected with the switching structure; the switching structure is used for leading the second lead out of the process chamber and is electrically connected with the voltage reading device.
11. The dc bias voltage detection jig of claim 10, wherein the adapter structure comprises a first adapter, a second adapter and a shielding wire, wherein the first adapter is disposed on the housing; the second adapter is electrically connected with the voltage reading device and is used for being installed on the outer wall of the process chamber; one end of the shielding wire is electrically connected with the first adapter, and the other end of the shielding wire is electrically connected with the second adapter; an insulating layer is coated on the shield wire.
12. The dc bias voltage detection jig according to claim 10, wherein the probe further comprises an insulating member and an insulating medium layer, wherein the insulating member is disposed in the housing and covers a portion of the first lead wire located in the housing and at least a connection portion of the first lead wire and the voltage dividing element; the insulating medium layer covers the outer surface of the shell.
13. A bottom electrode system comprising a susceptor disposed in a process chamber, a matcher electrically connected to the susceptor, and a dc bias detecting device for detecting a dc bias of a wafer placed on the susceptor, the dc bias detecting device employing the dc bias detecting device of claim 7 or 8.
CN202011194899.7A 2020-10-30 2020-10-30 DC bias detection method, device, jig and lower electrode system Pending CN112345814A (en)

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