SPV method non-contact silicon wafer PN type measuring device

Abstract

The utility model relates to the technical field of silicon wafer detection, specifically, to a SPV method non -contact silicon wafer PN type measuring device, including power module, controller module, LED module, amplifier circuit and condenser plate. In the utility model, the product life is improved by replacing laser tube with narrowband LED, and the energy of light can be adjusted, the utilization of light source can be improved, the attenuation problem is effectively solved, in addition, by adjusting the frequency of the light source of collection and emission, through the pulse control of controllable different frequency, the surrounding interference can be effectively avoided.

Description

Technical Field

[0001] This utility model relates to the field of silicon wafer testing technology, specifically to a non-contact silicon wafer PN type measuring device using the SPV method. Background Technology

[0002] Silicon wafer inspection includes quality inspection, thickness inspection, microcrack inspection, industrial problem diagnosis, surface organic matter inspection, resistivity inspection, etc. Silicon wafer inspection ensures the quality, performance and consistency of silicon wafers. Its operation process includes multiple aspects such as appearance inspection and defect inspection of silicon wafers. Among them, measuring the PN type of silicon wafers can determine the conversion efficiency of silicon wafers.

[0003] For example, CN209878940U discloses a novel silicon material PN type detection device, including a lower base, with support feet fixedly connected to the four corners of the upper end of the lower base, an upper base fixedly connected to the upper end of the four support feet, a pair of fixing blocks fixedly connected to the upper end of the lower base, threaded holes on the left end of each pair of fixing blocks, a first screw threadedly connected to the inner wall of each pair of threaded holes, a clamping block fixedly connected to the near end of each pair of first screws, a connecting block fixedly connected to the far end of each pair of first screws, a rotating block fixedly connected to the far end of each pair of connecting blocks, a first connecting block fixedly connected to the lower end of the upper base, a first internal thread groove on the lower end of the first connecting block, a second screw threadedly connected to the inner wall of the first internal thread groove, and a second connecting block fixedly connected to the lower end of the second screw. This device is suitable for PN type detection of silicon materials of different specifications and is easy to operate.

[0004] The detection device uses a detection body for detection. In existing technologies, the detection body generally uses a laser tube as the light source. Electrons and holes in the space charge region on the silicon wafer surface are separated by a built-in electric field, forming a photovoltage. P-type silicon exhibits a positive charge due to the doping of trivalent elements, while N-type silicon exhibits a negative charge due to the doping of pentavalent elements. At the same time, the polarity of the photovoltage can be directly measured using a contact probe to determine the conductivity type, or the conductivity type can be determined by non-contact measurement of the induced electromotive force using the capacitance effect. However, the lifespan of a laser tube is generally 5,000-10,000 hours. Using a laser tube as the light source has a certain impact on the product's lifespan. Furthermore, the energy of the light source is fixed and decreases with use. Therefore, the maximum energy is generally used initially, but high energy also affects the lifespan. In addition, the generation and recombination of surface photovoltage occur transiently, and the electromotive force generated by the charge is also small. Therefore, there are certain requirements for the acquisition to resist interference. Currently, the acquisition and illumination frequencies of existing products are generally fixed. If there is interference at a specific frequency, there is a possibility of failure.

[0005] To improve product lifespan and avoid test interference, a non-contact silicon wafer PN type measurement device using the SPV method is proposed. Utility Model Content

[0006] The purpose of this invention is to provide a non-contact silicon wafer PN type measurement device using the SPV method to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides a non-contact silicon wafer PN type measurement device using the SPV method, comprising a power supply module, a controller module, an LED module, an amplifier circuit, and a capacitor board. The power supply module is connected to the controller module, the controller module is connected to the LED module, the capacitor board is connected to the amplifier circuit, and the amplifier circuit is connected to the controller module.

[0008] The controller module drives and adjusts the LED module to excite the sample under test. The amplifier circuit amplifies the surface photovoltage signal collected by the capacitor plate and is then collected by the controller module.

[0009] As a further improvement to this technical solution, the controller module includes a controller unit, which is equipped with a DAC module, timer 1, timer 2, a data processing module, an ADC module, and a communication interface.

[0010] As a further improvement to this technical solution, the LED module includes an LED driving circuit and an LED light source connected to the LED driving circuit, and the DAC module is connected to the LED driving circuit.

[0011] As a further improvement to this technical solution, the LED driving circuit includes a microcontroller U5, a chip U7, and terminals CN1 and CN5, wherein...

[0012] The VDDA, VDD_4, VDD_1, VDD_2, and VDD_3 pins of the microcontroller U5 are all connected to the +VCC terminal;

[0013] The VSSA, VSS_4, VSS_2, and VSS_3 pins of the microcontroller U5 are all grounded;

[0014] The PB9 pin of the microcontroller U5 is connected to resistor R22, the resistor R22 is connected to the G terminal of transistor Q2, the D terminal of transistor Q2 is connected to pin 1 of terminal CN1, the S terminal of transistor Q2 is connected to the S terminal of chip U2, the D terminal of chip U2 is connected to resistor R1, and the resistor R1 is connected to the +VCC terminal.

[0015] The PC4 pin of the microcontroller U5 is connected to the V3 pin of the chip U7, the PC5 pin is connected to the RXD pin of the chip U7, the VSS_1 pin is connected to capacitor C37 and grounded, and the capacitor C37 is connected to the VCC pin of the chip U7.

[0016] The UD+ pin of the chip U7 is connected to potentiometer R21 and then to pin 2 of terminal CN5. Potentiometer R21 is grounded.

[0017] The UD-pin of the chip U7 is connected to potentiometer R20 and then to pin 3 of terminal CN5, and pin 4 of terminal CN5 is grounded;

[0018] The GND pin of the chip U7 is grounded, and the TXD pin is connected to the +VCC terminal.

[0019] As a further improvement to this technical solution, the LED driving circuit also includes an operational amplifier U8.1.

[0020] Pin 1 of the operational amplifier U8.1 is connected to resistor R2 and capacitor C3, and resistor R2 is connected to the G terminal of the chip U2;

[0021] Pin 2 of the operational amplifier U8.1 is connected to resistor R4 and capacitor C5, and then connected to the other end of capacitor C3. Resistor R4 is connected to resistor R3, and resistor R3 is connected to pin PC12 of the microcontroller U7.

[0022] Pin 3 of the operational amplifier U8.1 is connected to resistor R6. Resistor R6 is connected to diode ZD1, resistors R7 and R8 and connected to pin 2 of terminal CN1. Diode ZD1 is connected to the other end of resistor R7 and the other end of resistor R8 and connected to pin 3 of terminal CN1.

[0023] Pin 4 of the operational amplifier U8.1 is connected to the other end of the resistor R5 and grounded;

[0024] The operational amplifier U8.1 has a capacitor C4 connected to pin 8 and connected to the +VCC terminal, and the capacitor C4 is grounded.

[0025] As a further improvement to this technical solution, the amplification circuit includes operational amplifier U4.1.

[0026] Pin 1 of the operational amplifier U4.1 is connected to resistors R10 and R12 and capacitors C11 and C12. Resistor R10 is connected to resistor R9 and capacitor C8 and diode ZD2. Capacitor C8 is connected to the other end of diode ZD2 and grounded. Resistor R9 is connected to pin PB15 of the microcontroller U7.

[0027] Pin 2 of the operational amplifier U4.1 is connected to resistor R11. Resistor R11 is connected to the other end of resistor R12, the other end of capacitor C11, the other end of capacitor C12, diodes D1 and D2 are connected in parallel to pin 4 of terminal CN1.

[0028] The operational amplifier U4.1 has capacitors C6 and C7 connected to pin 3 and grounded.

[0029] Pin 4 of the operational amplifier U4.1 is connected to the other end of capacitor C6, and the other end of capacitor C7 is connected in parallel to the -VCC terminal;

[0030] The operational amplifier U4.1 has its 8th pin connected to capacitors C9 and C10 and connected to the +VCC terminal. Both capacitors C9 and C10 are connected to the other end of diodes D1 and D2 and grounded.

[0031] As a further improvement to this technical solution, the LED light source is an LED lamp with a narrow band illumination wavelength range of 660nm.

[0032] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0033] In this SPV method non-contact silicon wafer PN type measurement device, the product life is improved by replacing the laser tube with a narrow-band LED, and the light energy is adjustable, which can improve the utilization rate of the light source and effectively solve the attenuation problem. In addition, by adjusting the frequency of the acquisition and emission light source, and through controllable pulse control of different frequencies, the surrounding interference can be effectively avoided. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0035] Figure 2 This is a flowchart of the testing process for this utility model;

[0036] Figure 3 The LED driver circuit of this utility model Figure 1 ;

[0037] Figure 4 The LED driver circuit of this utility model Figure 2 ;

[0038] Figure 5 The amplifier circuit of this utility model Figure 1 . Detailed Implementation

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0040] Currently, foreign products generally use laser tubes as light sources. Electrons and holes in the space charge region on the silicon wafer surface will be separated by a self-built electric field to form a photovoltage. P-type silicon exhibits a positive charge due to the doping of trivalent elements, while N-type silicon exhibits a negative charge due to the doping of pentavalent elements. At the same time, the polarity of the photovoltage can be directly measured using a contact probe to determine the conductivity type, or the induced electromotive force can be measured non-contactly using the capacitance effect to determine the conductivity type.

[0041] However, laser tubes are currently used as the light source, but the lifespan of laser tubes is limited, which has a certain impact on the lifespan of the product. In addition, the generation and recombination of surface photovoltage occur transiently, and the electromotive force generated by the charge is also very small. Therefore, there are certain requirements for the acquisition and anti-interference capabilities. Currently, the acquisition and illumination frequencies of existing products are generally fixed. If there is interference at a specific frequency, there is a possibility of failure.

[0042] Please see Figures 1-5 As shown, this embodiment provides a non-contact silicon wafer PN type measurement device using the SPV method, including a power supply module, a controller module, an LED module, an amplifier circuit, and a capacitor board. The power supply module is connected to the controller module, the controller module is connected to the LED module, the capacitor board is connected to the amplifier circuit, and the amplifier circuit is connected to the controller module.

[0043] The controller module drives and adjusts the LED module to excite the sample under test. The amplifier circuit amplifies the surface photovoltage signal collected by the capacitor plate, which is then acquired by the controller module.

[0044] The power module provides power to the system, the amplifier circuit mainly amplifies the small electromotive force, and the capacitor plate couples the surface photovoltage through the capacitance effect.

[0045] Principle: The controller module reasonably adjusts the acquisition and light source frequency to avoid interference from other surrounding electronic devices, and reasonably controls the power supply of the LED module. It can be set by program or automatically. The voltage is acquired by the capacitor board and amplified by the amplifier circuit, and then the PN conductivity type is analyzed by voltage analysis.

[0046] The surface photovoltage method (SPV) for testing the conductivity type of a semiconductor is a method that utilizes the photovoltaic effect (photoinduced electron transition) on a solid surface. When monochromatic light with energy greater than the bandgap of a semiconductor material is irradiated onto the surface of the semiconductor material, the surface voltage generated is used to obtain the conductivity type.

[0047] The controller module includes a controller unit, which is equipped with a DAC module for digital-to-analog conversion and adjustment of the LED module, a timer 1 for driving the LED module, a timer 2 for acquiring photovoltaic voltage, a data processing module for collecting data, an ADC module for analog-to-digital conversion, and a communication interface for data communication.

[0048] The LED module includes an LED driver circuit and an LED light source connected to the LED driver circuit. The DAC module is connected to the LED driver circuit. The controller unit controls the LED light source through the LED driver circuit via the DAC module and timer 1.

[0049] The LED driver circuit includes a microcontroller U5, a chip U7, and terminals CN1 and CN5.

[0050] The VDDA, VDD_4, VDD_1, VDD_2, and VDD_3 pins of the microcontroller U5 are all connected to the +VCC terminal;

[0051] The VSSA, VSS_4, VSS_2, and VSS_3 pins of the microcontroller U5 are all grounded;

[0052] Connect resistor R22 to pin PB9 of microcontroller U5. Connect resistor R22 to the gate (G) terminal of transistor Q2. Connect the drain (D) terminal of transistor Q2 to pin 1 of terminal CN1. Connect the source (S) terminal of transistor Q2 to the source (S) terminal of chip U2. Connect the drain (D) terminal of chip U2 to resistor R1. Connect resistor R1 to the +VCC terminal.

[0053] The PC4 pin of the microcontroller U5 is connected to the V3 pin of the chip U7, the PC5 pin is connected to the RXD pin of the chip U7, the VSS_1 pin is connected to capacitor C37 and grounded, and capacitor C37 is connected to the VCC pin of the chip U7.

[0054] The UD+ pin of chip U7 is connected to potentiometer R21 and then to pin 2 of terminal CN5. Potentiometer R21 is grounded.

[0055] The UD-pin of chip U7 is connected to potentiometer R20 and then to pin 3 of terminal CN5. Pin 4 of terminal CN5 is grounded.

[0056] The GND pin of chip U7 is grounded, and the TXD pin is connected to the +VCC terminal.

[0057] In this circuit, transistor Q2 is a MOSFET, and pins 1 and 2 of terminal CN1 are connected to the two pins of the LED light source. The PB9 pin of microcontroller U5 controls transistor Q2 through the PPG function of timer 1 to realize the frequency blinking function of the LED light source.

[0058] The LED driver circuit also includes operational amplifier U8.1.

[0059] Pin 1 of operational amplifier U8.1 is connected to resistor R2 and capacitor C3. Resistor R2 is connected to the gate (G) terminal of chip U2.

[0060] Pin 2 of operational amplifier U8.1 is connected to resistor R4 and capacitor C5, and then connected to the other end of capacitor C3. Resistor R4 is connected to resistor R3, and resistor R3 is connected to pin PC12 of microcontroller U7.

[0061] Pin 3 of operational amplifier U8.1 is connected to resistor R6. Resistor R6 is connected to diode ZD1, resistors R7 and R8 and connected in parallel to pin 2 of terminal CN1. Diode ZD1 is connected to the other end of resistor R7 and the other end of resistor R8 and connected in parallel to pin 3 of terminal CN1.

[0062] Pin 4 of operational amplifier U8.1 is connected to the other end of resistor R5 and grounded;

[0063] The 8th pin of the operational amplifier U8.1 is connected to capacitor C4 and then to the +VCC terminal. Capacitor C4 is grounded.

[0064] The working principle and process of the U7 microcontroller controlling LED energy through DA conversion are as follows:

[0065] LED light sources are current-driven components; the voltage determines the LED's energy, i.e., its brightness. This brightness can be calculated as follows: For example, given a voltage of 3.3V and a driving current of 2V for the LED, the voltage across the resistor is 3.3 - 2 = 1.3V, and the current flowing through it is I = U / R = 1.3 / R. To change the current, the following methods can be used:

[0066] 1. Change the value of U, keep R constant, I = U - ULED(2.0) / R, when U = 3V I = (3-2) / R, when U = 5V I = (5-2) / R, I increases by 3 times;

[0067] 2. Change the value of R while keeping U constant.

[0068] This embodiment uses a microcontroller U7 to control the output voltage of the DA converter, thereby controlling the voltage magnitude to achieve LED light source energy control.

[0069] The PC12 pin of the microcontroller U7 is the DA output pin. The voltage output by the microcontroller U7 through its PC12 pin is converted into a variable constant current source by the operational amplifier U8.1, which can be used to control the intensity of the LED light source.

[0070] The amplifier circuit includes operational amplifier U4.1.

[0071] Pin 1 of operational amplifier U4.1 is connected to resistors R10 and R12 and capacitors C11 and C12. Resistor R10 is connected to resistor R9 and capacitor C8 and diode ZD2. Capacitor C8 is connected to the other end of diode ZD2 and grounded. Resistor R9 is connected to pin PB15 of microcontroller U7.

[0072] Pin 2 of operational amplifier U4.1 is connected to resistor R11. Resistor R11 is connected to the other end of resistor R12, the other end of capacitor C11, the other end of capacitor C12, and diodes D1 and D2 are connected in parallel to pin 4 of terminal CN1.

[0073] Pin 3 of operational amplifier U4.1 is connected to capacitors C6 and C7 and grounded;

[0074] Pin 4 of operational amplifier U4.1 is connected to the other end of capacitor C6 and the other end of capacitor C7, and then connected in parallel to the -VCC terminal.

[0075] Pin 8 of operational amplifier U4.1 is connected to capacitors C9 and C10 and then to the +VCC terminal. Both capacitors C9 and C10 are connected to the other ends of diodes D1 and D2 and then grounded.

[0076] Pin PB15 of the microcontroller U7 is the AD acquisition pin. The signal generated by the capacitor board is introduced through pins 3 and 4 of terminal CN1, amplified by operational amplifier U4.1, and then acquired by the microcontroller U7 through its pin PB15.

[0077] Furthermore, the LED light source is a narrowband LED lamp with a wavelength range of 660nm. Narrowband 660nm LED lamps have the characteristics of long life, low energy consumption, and no ultraviolet radiation.

[0078] When the sample under test is an N-type silicon wafer, the surface of the sample under test is negatively charged, the capacitor induces a positive charge, and the ADC module collects the positive charge; when the sample under test is a P-type silicon wafer, the surface of the sample under test is positively charged, the capacitor induces a negative charge, and the ADC module collects the negative charge.

[0079] In this embodiment, a narrowband LED is used instead of a laser tube. The lifespan of the LED is over 100,000 hours, and the light energy of the LED is sufficient to excite the semiconductor material to generate a surface photovoltage. The magnitude of the surface electromotive force generated is the same as that of the laser tube. The light energy is adjustable, which can improve the utilization rate of the light source, effectively solve the attenuation problem, and adjust the frequency of the light source acquisition and emission. Through controllable pulse control of different frequencies, the surrounding interference can be effectively avoided.

[0080] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A non-contact silicon wafer PN type measurement device using the SPV method, characterized in that: It includes a power supply module, a controller module, an LED module, an amplifier circuit, and a capacitor board. The power supply module is connected to the controller module, the controller module is connected to the LED module, the capacitor board is connected to the amplifier circuit, and the amplifier circuit is connected to the controller module. The controller module drives and adjusts the LED module to excite the sample under test. The amplifier circuit amplifies the surface photovoltage signal collected by the capacitor plate and is then collected by the controller module.

2. The SPV method non-contact silicon wafer PN type measurement device according to claim 1, characterized in that: The controller module includes a controller unit, which is equipped with a DAC module, timer 1, timer 2, a data processing module, an ADC module, and a communication interface.

3. The SPV method non-contact silicon wafer PN type measurement device according to claim 2, characterized in that: The LED module includes an LED driving circuit and an LED light source connected to the LED driving circuit, and the DAC module is connected to the LED driving circuit.

4. The SPV method non-contact silicon wafer PN type measurement device according to claim 3, characterized in that: The LED driving circuit includes a microcontroller U5, a chip U7, and terminals CN1 and CN5, wherein... The VDDA, VDD_4, VDD_1, VDD_2, and VDD_3 pins of the microcontroller U5 are all connected to the +VCC terminal; The VSSA, VSS_4, VSS_2, and VSS_3 pins of the microcontroller U5 are all grounded; The PB9 pin of the microcontroller U5 is connected to resistor R22, the resistor R22 is connected to the G terminal of transistor Q2, the D terminal of transistor Q2 is connected to pin 1 of terminal CN1, the S terminal of transistor Q2 is connected to the S terminal of chip U2, the D terminal of chip U2 is connected to resistor R1, and the resistor R1 is connected to the +VCC terminal. The PC4 pin of the microcontroller U5 is connected to the V3 pin of the chip U7, the PC5 pin is connected to the RXD pin of the chip U7, the VSS_1 pin is connected to capacitor C37 and grounded, and the capacitor C37 is connected to the VCC pin of the chip U7. The UD+ pin of the chip U7 is connected to potentiometer R21 and then to pin 2 of terminal CN5. Potentiometer R21 is grounded. The UD-pin of the chip U7 is connected to potentiometer R20 and then to pin 3 of terminal CN5, and pin 4 of terminal CN5 is grounded; The GND pin of the chip U7 is grounded, and the TXD pin is connected to the +VCC terminal.

5. The SPV method non-contact silicon wafer PN type measurement device according to claim 4, characterized in that: The LED driver circuit also includes an operational amplifier U8.

1. Pin 1 of the operational amplifier U8.1 is connected to resistor R2 and capacitor C3, and resistor R2 is connected to the G terminal of the chip U2; Pin 2 of the operational amplifier U8.1 is connected to resistor R4 and capacitor C5, and then connected to the other end of capacitor C3. Resistor R4 is connected to resistor R3, and resistor R3 is connected to pin PC12 of the microcontroller U7. Pin 3 of the operational amplifier U8.1 is connected to resistor R6. Resistor R6 is connected to diode ZD1, resistors R7 and R8 and connected to pin 2 of terminal CN1. Diode ZD1 is connected to the other end of resistor R7 and the other end of resistor R8 and connected to pin 3 of terminal CN1. Pin 4 of the operational amplifier U8.1 is connected to the other end of the resistor R5 and grounded; The operational amplifier U8.1 has a capacitor C4 connected to pin 8 and connected to the +VCC terminal, and the capacitor C4 is grounded.

6. The SPV method non-contact silicon wafer PN type measurement device according to claim 4, characterized in that: The amplifier circuit includes operational amplifier U4.

1. Pin 1 of the operational amplifier U4.1 is connected to resistors R10 and R12 and capacitors C11 and C12. Resistor R10 is connected to resistor R9 and capacitor C8 and diode ZD2. Capacitor C8 is connected to the other end of diode ZD2 and grounded. Resistor R9 is connected to pin PB15 of the microcontroller U7. Pin 2 of the operational amplifier U4.1 is connected to resistor R11. Resistor R11 is connected to the other end of resistor R12, the other end of capacitor C11, the other end of capacitor C12, diodes D1 and D2 are connected in parallel to pin 4 of terminal CN1. The operational amplifier U4.1 has capacitors C6 and C7 connected to pin 3 and grounded. Pin 4 of the operational amplifier U4.1 is connected to the other end of capacitor C6, and the other end of capacitor C7 is connected in parallel to the -VCC terminal; The operational amplifier U4.1 has its 8th pin connected to capacitors C9 and C10 and connected to the +VCC terminal. Both capacitors C9 and C10 are connected to the other end of diodes D1 and D2 and grounded.

7. The SPV method non-contact silicon wafer PN type measurement device according to claim 1, characterized in that: The LED light source is a narrowband LED lamp with an illumination wavelength range of 660nm.

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