CN212207647U

CN212207647U - Test circuit of Langmuir probe

Info

Publication number: CN212207647U
Application number: CN202020756997.4U
Authority: CN
Inventors: 陈海清; 陈文聪
Original assignee: Shenzhen Aike Technology Co ltd
Current assignee: Shenzhen Aike Technology Co ltd
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2020-12-22
Anticipated expiration: 2030-05-09

Abstract

The utility model discloses a Langmuir probe test circuit, which comprises an active load circuit, a passive load circuit and a coaxial interface connected with the active load circuit and the passive load circuit; the coaxial interface is electrically connected with the Langmuir probe; the active load circuit comprises a voltage-stabilized power supply module, a current source module and a diode array module. The utility model discloses have the advantage that stability is high, the noise is low, repeatability is high to the detection of Langmuir probe.

Description

Test circuit of Langmuir probe

Technical Field

The utility model relates to a measuring equipment technical field, the more specifically test circuit of langmuir probe that says so.

Background

The low-temperature plasma is widely applied to semiconductor manufacturing process links such as etching, deposition, film coating and the like. As semiconductor processing technology gradually moves into 7 nm and even 5 nm processes, device manufacturers need to adjust manufacturing equipment control parameters to provide fine control over the plasma state inside the semiconductor equipment. These controls must be based on a large number of experimental data measurements, i.e. experimental diagnostics of information on plasma density, electron temperature, plasma potential and spatial distribution of these parameters.

The Langmuir probe is a key device for measurement and diagnosis of low-temperature plasma, and works by biasing the probe tip to a set voltage and simultaneously measuring the weak current collected by the tip. Typically, the current collected by the probe tip depends on three different intervals in which the tip voltage is present: (1) when the voltage of the needle point is lower than the suspension potential of the plasma, the current collected by the probe is microampere-level ion saturation current; (2) when the voltage of the needle point is higher than the plasma potential, the current collected by the probe is electron saturation current in milliampere level; (3) when the tip voltage is in the blocking region between the floating potential and the plasma potential, the current collected by the probe gradually transitions from ion saturation current in the microampere range to electron saturation current in the milliamp range, and the current exponentially spans multiple orders of magnitude with voltage.

The voltage and current curve of the needle point voltage in the blocking area can obtain the most abundant plasma parameter information, such as an electron energy distribution function, electron temperature, electron density and the like. Therefore, a high-precision langmuir probe must have a precise measurement capability to measure the exponential form current signal across multiple orders of magnitude within the blocking region.

In order to guarantee the measurement accuracy of the Langmuir probe, the nonlinear voltage-current curve measurement capability of the probe needs to be regularly detected by using an analog load. Probes are typically tested using resistors or diodes as analog loads. The voltage and current obtained by using the resistance load are in a linear relation, and curve characteristics of a saturation region and a retardation region are lacked; the voltage-current curve obtained by using the diode load only has a reverse cut-off region and a forward conduction region, the reverse cut-off region has almost no current, the forward conduction region has no current saturation characteristic, and the testable voltage range is usually less than 1V. Therefore, the resistive load and the diode load are only suitable for low-precision test of the probe, and a test calibration instrument with high stability, low noise and high repetition precision aiming at the Langmuir probe is lacked at present.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome prior art's not enough, provide a test circuit of langmuir probe.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a test circuit of a Langmuir probe comprises an active load circuit, a passive load circuit and a coaxial interface connected with the active load circuit and the passive load circuit; the coaxial interface is electrically connected with the Langmuir probe; the active load circuit comprises a voltage-stabilized power supply module, a current source module and a diode array module.

The further technical scheme is as follows: the current source module comprises a triode Q1 and a triode Q2; the base electrode of the triode Q1 is electrically connected with the base electrode of the triode Q2; the emitting electrodes of the triode Q1 and the triode Q2 are grounded; the collector of the triode Q1 is electrically connected with the voltage-stabilized power supply module; the collector of the triode Q2 is electrically connected with the diode array module; the triode Q1 is electrically connected with the voltage-stabilized power supply module through a plurality of pull-up resistors connected in parallel.

The further technical scheme is as follows: the pull-up resistor comprises a pull-up resistor R1, a pull-up resistor R2 and a pull-up resistor R3; the pull-up resistor R1, the pull-up resistor R2 and the pull-up resistor R3 are connected in parallel and electrically connected with the voltage-stabilized power supply module through the switch S1.

The further technical scheme is as follows: the diode array module comprises a plurality of diode unit groups; the anode input end of the diode unit group is electrically connected with the coaxial interface, and the cathode input end of the diode unit group is electrically connected with the collector electrode of the triode Q2; the diode unit group is formed by connecting a plurality of diodes in series.

The further technical scheme is as follows: the number of the diode unit groups is three, and the diode unit groups are a diode unit group, a diode unit group and a diode unit group; the diode unit group, the diode unit group and the diode unit group are connected in series; a first contact is arranged between the anode end of the diode unit group and the cathode end of the diode unit group; a second contact is arranged between the anode ends of the two groups of diode units and the cathode ends of the three groups of diode units; the anode ends of the three groups of the diode units are provided with third contacts; the coaxial interface is provided with a gear switch S2, and the gear switch S2 is electrically contacted with the first contact, the second contact and the third contact respectively.

The further technical scheme is as follows: the diode unit group comprises a diode D1, a diode D2, a diode D3, a diode D4 and a diode D5; the diode D1, the diode D2, the diode D3, the diode D4 and the diode D5 are sequentially connected in series; the two groups of diode units comprise a diode D6, a diode D7, a diode D8, a diode D9 and a diode D10; the diode D6, the diode D7, the diode D8, the diode D9 and the diode D10 are sequentially connected in series; the three groups of diode units comprise a diode D11, a diode D12, a diode D13, a diode D14 and a diode D15; the diode D11, the diode D12, the diode D13, the diode D14 and the diode D15 are sequentially connected in series; the first contact is connected between the anode of the diode D5 and the cathode of the diode D6; the second contact is connected between the anode of the diode D10 and the cathode of the diode D11; the third contact is connected to the anode terminal of the diode D15.

The further technical scheme is as follows: the voltage-stabilized power supply module comprises a transformer T1, a bridge rectifier DR1, a capacitor and a voltage stabilizer U1; the transformer T1 is used for transforming the input voltage; the bridge rectifier DR1 is used for rectifying the input voltage; the capacitor is used for filtering voltage; the regulator U1 is used to regulate the rectified and filtered voltage.

The further technical scheme is as follows: the triode Q1 and the triode Q2 are NPN bipolar triodes with the same model.

The further technical scheme is as follows: the passive load circuit comprises a bypass resistance module; the bypass resistor module comprises a switch S3, a resistor R4, a resistor R5 and a resistor R6; the resistor R4, the resistor R5 and the resistor R6 are connected in parallel; one ends of the resistor R4, the resistor R5 and the resistor R6 are electrically connected with the switch S3, and the other ends are grounded.

Compared with the prior art, the utility model beneficial effect be: the utility model discloses have the advantage that stability is high, the noise is low, repeatability is high to the detection of Langmuir probe.

The foregoing is a summary of the present invention, and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments, which is provided for the purpose of illustration and understanding of the present invention.

Drawings

Figure 1 is a block diagram of a langmuir probe test circuit according to the present invention;

fig. 2 is a schematic circuit diagram of a test circuit of a langmuir probe according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in further detail with reference to the accompanying drawings and the following detailed description.

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and to simplify the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "secured" are to be construed broadly and can, for example, be connected or detachably connected or integrated; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above should not be understood to necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by one skilled in the art.

Drawings 1 to 2 are the utility model discloses a drawing.

The present embodiment provides a circuit for testing a langmuir probe, as shown in fig. 1 and 2, including an active load circuit 10, a passive load circuit 20, and a coaxial interface J1(30) connected to the active load circuit 10 and the passive load circuit 20. The coaxial interface J1(30) electrically connects to the langmuir probe. The active load circuit 10 includes a regulated power supply module 11, a current source module 12 and a diode array module 13. The active load circuit 10 and the passive load circuit 20 are connected in parallel to a coaxial interface J1(30) so that the active load circuit 10 and the passive load circuit 20 are connected in parallel to form an analog load, and the coaxial interface J1(30) is connected to the langmuir probe to receive the probe scanning voltage and feed back the probe current.

The regulated power supply module 11 generates a stable low ripple voltage to supply power to the current source module 12.

The current source module 12 includes a transistor Q1 and a transistor Q2. The base of transistor Q1 is electrically connected to the base of transistor Q2. The emitters of the transistor Q1 and the transistor Q2 are grounded. The collector of the transistor Q1 is electrically connected to the regulated power supply module 11. The collector of the transistor Q2 is electrically connected to the diode array module 13. The transistor Q1 is electrically connected to the regulated power supply module 11 through a plurality of pull-up resistors connected in parallel. The triode Q1 and the triode Q2 are NPN bipolar triodes with the same model.

The pull-up resistor comprises a pull-up resistor R1, a pull-up resistor R2 and a pull-up resistor R3. The pull-up resistor R1, the pull-up resistor R2 and the pull-up resistor R3 are connected in parallel and electrically connected with the regulated power supply module 11 through the switch S1.

The diode array module 13 includes a plurality of diode cell groups. The anode input end of the diode unit group is electrically connected with the coaxial interface J1(30), and the cathode input end of the diode unit group is electrically connected with the collector of the triode Q2. The diode unit group is formed by connecting a plurality of diodes in series.

Specifically, the number of the diode unit groups is three, and the diode unit groups are a diode unit group, a diode unit group and a diode unit group. The diode unit group, the diode unit group and the diode unit group are mutually connected in series. A first contact is arranged between the anode end of the diode unit group and the cathode end of the diode unit group. And a second contact is arranged between the anode ends of the two groups of diode units and the cathode ends of the three groups of diode units. And the anode ends of the three groups of the diode units are provided with third contacts. The coaxial interface J1(30) is provided with a position switch S2, and the position switch S2 is electrically contacted with the first contact, the second contact and the third contact respectively.

More specifically, the diode unit group includes a diode D1, a diode D2, a diode D3, a diode D4, and a diode D5. The diode D1, the diode D2, the diode D3, the diode D4 and the diode D5 are sequentially connected in series. The diode unit set comprises a diode D6, a diode D7, a diode D8, a diode D9 and a diode D10. The diode D6, the diode D7, the diode D8, the diode D9 and the diode D10 are sequentially connected in series; the three groups of diode units comprise a diode D11, a diode D12, a diode D13, a diode D14 and a diode D15. The diode D11, the diode D12, the diode D13, the diode D14 and the diode D15 are sequentially connected in series. The first contact is connected between the anode of diode D5 and the cathode of diode D6. A second contact is connected between the anode of diode D10 and the cathode of diode D11; the third contact is connected to the anode terminal of the diode D15.

Regulated power supply module 11 includes transformer T1, bridge rectifier DR1, capacitor and regulator U1. The transformer T1 is used to transform the input voltage. The bridge rectifier DR1 is used to rectify the input voltage. The capacitor is used for filtering the voltage. Regulator U1 is used to regulate the rectified and filtered voltage.

Preferably, the voltage regulator U1 is a three-terminal voltage regulator.

The passive load circuit 20 comprises a shunt resistance module 21. The bypass resistor module 21 includes a switch S3, a resistor R4, a resistor R5, and a resistor R6. The resistor R4, the resistor R5 and the resistor R6 are connected in parallel. One ends of the resistor R4, the resistor R5 and the resistor R6 are electrically connected with the switch S3, and the other ends are grounded.

The active load circuit 10 can generate currents similar to the electron saturation current and the ion saturation current of the langmuir probe driven by the probe scan voltage, the load current is mainly the reverse blocking current of the diodes (diode D1 to diode D15) under negative high voltage, the load current is mainly the linear amplification current of the transistor (transistor Q1 or transistor Q2) under positive high voltage, and the load current is mainly the superposition of the forward conduction current of the diodes (diode D1 to diode D15) and the saturation region current of the transistor (transistor Q1 or transistor Q2) in the transition region.

In the present embodiment, the specific working principle is as follows: the voltage-stabilized power supply module 11 transforms the power frequency AC220V through a transformer T1, performs bridge rectification DR1, performs filtering through a capacitor C1, a capacitor C2, a capacitor C3, and performs voltage stabilization through a three-terminal regulator U1 to generate a direct-current voltage:

Vcc＝+5V，

the voltage Vcc supplies power to the current source module 12, so that one NPN transistor Q2 is in an amplification state, and the base current of the other NPN transistor Q1 is stabilized as follows:

IB＝(Vcc-VBE)/RB/2

VBE is the base emitter turn-on voltage of NPN transistor (transistor Q1 or transistor Q2), and RB is the resistance of pull-up resistor (R1, R2, R3) selected by the multi-band switch S1. The NPN transistor Q2 is connected to the cathode of the diode array module 13. When the langmuir probe to be tested generates a positive high voltage, a plurality of diodes (one group of diode units, two groups of diode units, or three groups of diode units connected in series) connected into a loop are all turned on in the forward direction, and the current of the active load circuit 10 is as follows:

IC＝IB*hf

hf is the current amplification factor of the NPN transistor (transistor Q1 or transistor Q2). When the langmuir probe to be tested generates a negative high voltage, the diodes (one group of diode units, two groups of diode units, or three groups of diode units connected in series) connected into the loop are all turned off in the reverse direction, and the current of the active load circuit 10 is as follows:

IC＝Is

is the reverse cut-off saturation current of diodes (one group of diode units, two groups of diode units, three groups of diode units or a plurality of groups of diode units are connected in series).

When the langmuir probe voltage to be tested is Vprobe, the current flowing through the shunt resistance module 21 is:

IL＝Vprobe/RL

RL is the resistance value of the resistor (R4, R5, R6) selected to be connected to the loop by the bypass resistor module 21 through the multi-level band switch S3.

The current collected by the probe through the coaxial interface 30 is the sum of the currents of the active load circuit 10 and the passive load circuit 20. When the langmuir probe to be tested generates a positive high voltage, the current collected by the probe through the coaxial interface 30 is:

IP＝(Vcc-VBE)/RB/2*hf+Vprobe/RL

when the langmuir probe to be tested generates a negative high voltage, the current collected by the probe through the coaxial interface 30 is:

IP＝Is+Vprobe/RL

when the voltage of the langmuir probe to be tested is gradually increased from the negative high voltage to the positive high voltage, the current collected by the probe through the coaxial interface 30 is a current which is between the two currents and exponentially increases with the probe voltage. By selecting the proper type of the transistor (transistor Q1 and transistor Q2) and the diode (diode D1 to diode D15), the detectable Langmuir probe voltage range is-200 and 200V, and the probe current range is 0-200 mA.

The utility model discloses a circuit has realized the adjustable function of the langmuir probe current of awaiting measuring through adjusting a plurality of many grades of wave band switches (switch S1, switch S2, switch S3) select to connect the different resistance (resistance R1 to resistance R6) resistances that get into the return circuit.

The utility model discloses a plasma Langmuir probe characteristic voltage current curve's accurate analog function produces microampere level's reverse saturation current in the negative high-pressure ion saturation region of probe, and the positive high-voltage electron saturation region of probe produces milliampere level's forward saturation current, produces the exponential form electric current between the two in the transition retardation region. The utility model discloses a simple and easy feasible technical scheme that the measuring capability of accurate test plasma Langmuir probe and provide.

Compared with the prior art, the utility model discloses detection to the langmuir probe has that stability is high, the noise is low, advantage that repetition precision is high.

The technical content of the present invention is further described by the embodiments only, so that the reader can understand it more easily, but the embodiments of the present invention are not limited thereto, and any technical extension or re-creation according to the present invention is protected by the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A test circuit of a Langmuir probe is characterized by comprising an active load circuit, a passive load circuit and a coaxial interface connected with the active load circuit and the passive load circuit; the coaxial interface is electrically connected with the Langmuir probe; the active load circuit comprises a voltage-stabilized power supply module, a current source module and a diode array module.

2. The Langmuir probe test circuit of claim 1, wherein the current source module comprises a transistor Q1, a transistor Q2; the base electrode of the triode Q1 is electrically connected with the base electrode of the triode Q2; the emitting electrodes of the triode Q1 and the triode Q2 are grounded; the collector of the triode Q1 is electrically connected with the voltage-stabilized power supply module; the collector of the triode Q2 is electrically connected with the diode array module; the triode Q1 is electrically connected with the voltage-stabilized power supply module through a plurality of pull-up resistors connected in parallel.

3. The circuit for testing a langmuir probe as claimed in claim 2, wherein the pull-up resistors comprise a pull-up resistor R1, a pull-up resistor R2, a pull-up resistor R3; the pull-up resistor R1, the pull-up resistor R2 and the pull-up resistor R3 are connected in parallel and electrically connected with the voltage-stabilized power supply module through the switch S1.

4. The circuit for testing a langmuir probe as claimed in claim 3, wherein the diode array module comprises a plurality of diode cell groups; the anode input end of the diode unit group is electrically connected with the coaxial interface, and the cathode input end of the diode unit group is electrically connected with the collector electrode of the triode Q2; the diode unit group is formed by connecting a plurality of diodes in series.

5. The circuit for testing a langmuir probe as claimed in claim 4, wherein the number of the diode units is three, namely one diode unit group, two diode units group and three diode units group; the diode unit group, the diode unit group and the diode unit group are connected in series; a first contact is arranged between the anode end of the diode unit group and the cathode end of the diode unit group; a second contact is arranged between the anode ends of the two groups of diode units and the cathode ends of the three groups of diode units; the anode ends of the three groups of the diode units are provided with third contacts; the coaxial interface is provided with a gear switch S2, and the gear switch S2 is electrically contacted with the first contact, the second contact and the third contact respectively.

6. The Langmuir probe test circuit of claim 5, wherein the diode unit group comprises a diode D1, a diode D2, a diode D3, a diode D4, and a diode D5; the diode D1, the diode D2, the diode D3, the diode D4 and the diode D5 are sequentially connected in series; the two groups of diode units comprise a diode D6, a diode D7, a diode D8, a diode D9 and a diode D10; the diode D6, the diode D7, the diode D8, the diode D9 and the diode D10 are sequentially connected in series; the three groups of diode units comprise a diode D11, a diode D12, a diode D13, a diode D14 and a diode D15; the diode D11, the diode D12, the diode D13, the diode D14 and the diode D15 are sequentially connected in series; the first contact is connected between the anode of the diode D5 and the cathode of the diode D6; the second contact is connected between the anode of the diode D10 and the cathode of the diode D11; the third contact is connected to the anode terminal of the diode D15.

7. The Langmuir probe test circuit of claim 1, wherein the regulated power supply module comprises a transformer T1, a bridge rectifier DR1, a capacitor and regulator U1; the transformer T1 is used for transforming the input voltage; the bridge rectifier DR1 is used for rectifying the input voltage; the capacitor is used for filtering voltage; the regulator U1 is used to regulate the rectified and filtered voltage.

8. The Langmuir probe test circuit of claim 2, wherein the transistor Q1 and the transistor Q2 are the same type NPN bipolar transistor.

9. The circuit for testing a langmuir probe as claimed in claim 1, wherein the passive load circuit comprises a shunt resistance module; the bypass resistor module comprises a switch S3, a resistor R4, a resistor R5 and a resistor R6; the resistor R4, the resistor R5 and the resistor R6 are connected in parallel; one ends of the resistor R4, the resistor R5 and the resistor R6 are electrically connected with the switch S3, and the other ends are grounded.