Four-probe measuring instrument, four-probe measuring system and method for measuring wafer to be measured by four-probe measuring instrument

Abstract

The present invention relates to the field of semiconductor detection technology, and provides a four-probe measuring instrument, a four-probe measuring system, and a method for a four-probe measuring instrument to measure a wafer to be measured. The four-probe measuring instrument includes: four probes, the probes having channels penetrating up and down; a laser emitter, the laser emitted by the laser emitter passing through the channels from top to bottom and irradiating the wafer to be measured; a fixing plate, the fixing plate having holes opposite to the probes, the probes passing through the holes, the fixing plate being used for fixing the probes and blocking the laser outside the probes from irradiating the wafer to be measured. In the present invention, a semiconductor is irradiated with a laser to cause electrons to transition to the conduction band, and at the same time generate holes to form electron-hole pairs, thereby improving the contact characteristics, enabling a good ohmic contact to be formed between the probes and the surface of the silicon wafer to be measured, and improving the stability of silicon wafer measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor detection, and in particular to a four-probe measuring instrument, a four-probe measuring system and a method for measuring a wafer to be measured by the four-probe measuring instrument. Background Art

[0002] The four-probe measuring instrument is a special instrument for measuring the resistivity and sheet resistance of semiconductor materials. It is used to measure the resistivity of rod-shaped and block-shaped semiconductor materials (including thick and thin slices) and the sheet resistance of the diffusion layer, ion implantation layer, and epitaxial layer on the silicon wafer. The instrument has the characteristics of high measurement accuracy, high sensitivity, good stability, wide measurement range, compact structure, and the measurement results are directly displayed in digital form, which is easy to use.

[0003] Due to the material properties of IIIV and IIVI compound semiconductors, SiC, gallium nitride, etc., it is difficult for the probe to form a good ohmic contact with the surface to be measured when using four-probe measurement, which makes it difficult to apply the traditional four-probe method in the preparation process of these semiconductors. The reasons why the above materials are difficult to form ohmic contact include 1. Complex band structure: These semiconductor materials usually have a more complex band structure, which is different from common silicon materials. This makes it difficult to match the electronic state and band at the contact interface, and it is difficult to achieve an ideal ohmic contact. For example, the band structure of gallium nitride has a high electron affinity and a wide bandgap, which makes it difficult to find a suitable metal material to form a low-resistance ohmic contact when in contact with metals. 2. Surface state influence: There are often a large number of surface states on the surface of compound semiconductors, which will capture carriers and affect the electrical properties of the contact interface. The surface state can form a potential barrier at the contact interface, hindering the transmission of carriers, thereby increasing the contact resistance and making it difficult to form an ohmic contact.

[0004] Wide bandgap semiconductors usually have high electron affinity and wide bandgap width, which makes it relatively easy for them to form a depletion layer at the surface. The formation of the depletion layer is related to factors such as the surface state of the semiconductor, impurity concentration, and external conditions. In wide bandgap semiconductors, the presence of surface states may lead to a decrease in the carrier concentration near the surface, thereby forming a depletion layer. It is also difficult for the probe to form a good ohmic contact with the surface to be measured when using a four-probe measurement.

[0005] Therefore, how to make the probe and the surface of the wafer under test form a good ohmic contact is a problem that needs to be solved at present. Summary of the invention

[0006] The purpose of the present invention is to provide a four-probe measuring instrument, a four-probe measuring system and a method for measuring a wafer to be measured by a four-probe measuring instrument, which can form good ohmic contact between the probes and the surface of the silicon wafer to be measured and improve the stability of silicon wafer measurement.

[0007] To achieve the above object, the present invention provides a four-probe measuring instrument, comprising:

[0008] Four probes, the probes having a through-channel extending vertically;

[0009] A laser emitter, the laser emitted by the laser emitter passing through the channel from top to bottom and irradiating the wafer to be measured;

[0010] A fixing plate, the fixing plate having a hole opposite to the probe, the probe passing through the hole, the fixing plate being used for fixing the probe and blocking the laser outside the probe from irradiating the wafer to be measured.

[0011] In an alternative embodiment, the four-probe measuring instrument further comprises:

[0012] A host computer, a control denoising module and a preamplifier connected in sequence;

[0013] The host computer sends a collection command to the control denoising module and controls the switching frequency of the laser emitter;

[0014] The control denoising module controls the operation of the preamplifier according to the collection instruction of the host computer;

[0015] The preamplifier is connected to the probes of the four-probe measuring instrument, and is used for applying current to two of the probes according to the collection instruction and receiving the voltage drops of the other two probes; and transmitting the voltage signal to the control denoising module;

[0016] The control denoising module amplifies the voltage signal and performs an operation with the switching frequency of the laser emitter to suppress noise that is not of the same frequency or in-phase as the switching frequency of the laser emitter, and then converts the voltage signal into a digital signal and sends it to the host computer.

[0017] In an alternative embodiment, the number of the channels is one or more.

[0018] The present invention further provides a four-probe measuring system, comprising the above four-probe measuring instrument, and further comprising a soft breakdown circuit structure, the soft breakdown circuit structure being used for connecting to the four-probe measuring instrument during measurement; the soft breakdown circuit structure comprises:

[0019] A capacitor, one end of the capacitor being grounded and the other end being connected to a charging circuit and a discharging circuit;

[0020] The charging circuit is used for charging the capacitor; the charging circuit comprises a plurality of parallel charging branches, each charging branch including a first switch for controlling the connection or disconnection of the current branch; the electric energy provided by each charging branch is different;

[0021] The discharge circuit is used to discharge the capacitor; the discharge circuit includes four parallel discharge branches, each of the discharge branches is connected to one probe of the four-probe measuring instrument, and each of the discharge branches includes a second switch for controlling the connection or disconnection of the current branch.

[0022] In an alternative embodiment, each of the charging branches includes a voltage source, the negative terminal of the voltage source is grounded, the positive terminal is connected to a resistor, the other end of the resistor is connected to the first switch, and the other end of the first switch is connected to the capacitor; the voltage sources of different charging branches provide different voltages.

[0023] In an alternative embodiment, each of the charging branches includes a current source, the negative terminal of the current source is grounded, the positive terminal is connected to a first resistor, the other end of the first resistor is connected to the first switch, the other end of the first switch is connected to the capacitor, and a second resistor is also connected between the positive and negative terminals of the current source; the current sources of different charging branches provide different currents.

[0024] In an alternative embodiment, the charging circuit includes:

[0025] A transformer;

[0026] A plurality of series-connected voltage-dividing resistors connected between the transformer and the reference ground;

[0027] A plurality of the charging branches are connected between different voltage-dividing resistors.

[0028] In an alternative embodiment, the discharge circuit includes:

[0029] A control switch connected to the capacitor;

[0030] A resistor connected to the other end of the control switch;

[0031] The four parallel discharge branches are connected to the other end of the resistor

[0032] The present invention also provides a method for a four-probe measuring instrument to measure a wafer to be measured. Using the above four-probe measuring instrument, the method includes:

[0033] Placing the wafer on the test platform;

[0034] Making physical contact between the probes of the four-probe measuring instrument and the wafer surface;

[0035] Irradiating the contact surface between the probe and the wafer with a laser;

[0036] Applying current to two of the needles of the four-probe measuring instrument and measuring the voltage drop between the other two needles.

[0037] In an alternative embodiment, when irradiating the contact surface between the probe and the wafer with a laser, the laser is irradiated at a set frequency or continuously irradiated.

[0038] The beneficial effects of the present invention are as follows:

[0039] In the present invention, a semiconductor is irradiated with a laser to cause electrons to transition to the conduction band, while holes are generated simultaneously, forming electron-hole pairs, thereby reducing the surface contact barrier of the semiconductor and improving the contact characteristics, enabling a good ohmic contact to be formed between the probe and the surface of the silicon wafer to be measured, and improving the stability of silicon wafer measurement. Description of the Drawings

[0040] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features, and advantages of the present invention will become more apparent. In the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0041] Figure 1 Shows a partial structural schematic diagram of a four-probe measuring instrument in an embodiment of the present invention.

[0042] Figure 2 Shows a schematic diagram of a laser irradiating a wafer through a channel of a probe in an embodiment of the present invention.

[0043] Figure 3 Shows a structural schematic diagram of a four-probe measuring system in an embodiment of the present invention.

[0044] Figure 4 Shows a schematic diagram of an inversion region on the surface of a wafer in the prior art without laser irradiation.

[0045] Figure 5 Shows a schematic diagram of an inversion region on the surface of a wafer in an embodiment of the present invention with laser irradiation.

[0046] Figure 6 Shows a schematic diagram of an inversion region on the surface of a wafer in another embodiment of the present invention with laser irradiation (the wavelength of the laser is longer than the wavelength in Figure 5 )

[0047] Figure 7 Shows a schematic diagram of a soft breakdown circuit structure in an embodiment of the present invention.

[0048] Figure 8 Shows a schematic diagram of a soft breakdown circuit structure in another embodiment of the present invention.

[0049] Figure 9 Shows a schematic diagram of a soft breakdown circuit structure in another embodiment of the present invention.

[0050] Reference Signs

[0051] 1 - Host computer; 2 - Control denoising module; 3 - Preamplifier; 4 - Probe; 5 - Channel; 6 - Fixed plate; 7 - Wafer. Detailed implementation mode

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in many different forms and is not limited to the specific embodiments described herein. The accompanying drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0053] It should be understood that when an element or layer is referred to as "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as the second element, component, region, layer or part.

[0054] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. are used herein for convenience of description to describe the relationship of one element or feature shown in the figure with other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the drawing is flipped, then the element or feature described as "under" or "beneath" or "below" another element or feature will be oriented "above" the other element or feature. Thus, the exemplary terms "under" and "below" can include both the upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are correspondingly interpreted.

[0055] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, identify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the related listed items.

[0056] Embodiment 1

[0057] Referring to Figures 1 to 3 , this embodiment provides a four-probe measuring instrument, comprising:

[0058] Four probes 4, the probes 4 having a through-channel 5 extending vertically;

[0059] A laser emitter, the laser emitted by the laser emitter passing through the channel 5 from top to bottom and irradiating the wafer 7 to be measured;

[0060] A fixing plate 6, the fixing plate 6 having a hole opposite to the probe 4, the probe 4 passing through the hole, the fixing plate 6 being used to fix the probe 4 and block the laser outside the probe from irradiating the wafer 7 to be measured.

[0061] Specifically, in this embodiment, the channel 5 of the probe 4 is one and is located at the central position of the probe. In other embodiments, the number of channels 5 can also be multiple. The laser emitter can be arranged on the frame of the four-probe measuring instrument and can be lifted and lowered simultaneously with the probe 4.

[0062] In this embodiment, the four-probe measuring instrument further comprises: a host computer 1, a control denoising module 2 and a preamplifier 3 connected in sequence; the host computer 1 sends a collection command to the control denoising module 2 and controls the switching frequency of the laser emitter; the control denoising module 2 controls the operation of the preamplifier 3 according to the collection instruction of the host computer 1; the preamplifier 3 is connected to the probe 4 of the four-probe measuring instrument and is used to apply current to two of the probes according to the collection instruction and receive the voltage drop of the other two probes; and transmit the voltage signal to the control denoising module 2; the control denoising module 2 amplifies the voltage signal and performs an operation with the switching frequency of the laser emitter to suppress noise that is not of the same frequency or in-phase as the switching frequency of the laser emitter, and then converts the voltage signal into a digital signal and sends it to the host computer 1.

[0063] In this embodiment, the control denoising module 2 is a lock-in amplifier.

[0064] In this embodiment, when the contact surface between the probe 4 and the wafer 7 is irradiated with laser, the laser is irradiated at a set frequency or continuously. When the contact surface between the probe 4 and the wafer 7 is irradiated with laser, the contact areas between the four probes and the wafer are irradiated simultaneously.

[0065] Referring to Figures 4 to 6 , the reason why ohmic contact can be formed between the probe and the wafer by irradiating the wafer with laser is as follows:

[0066] When a semiconductor is irradiated with laser, the atoms in the semiconductor will absorb the energy of the laser. This energy will cause the electrons in the atoms to transition from a low energy state to a high energy state. In a semiconductor, there are a conduction band and a valence band. Usually, electrons are in the valence band and there are almost no electrons in the conduction band. When an electron absorbs enough energy, it can transition to the conduction band and become a free electron. At the same time, a hole will be left in the valence band, and the hole can be regarded as a particle with a positive charge. In this way, electron-hole pairs, that is, carriers, are generated.

[0067] These carriers can move freely in the semiconductor, thus conducting electricity, making the original poorly contacted measurement become an ohmic contact that is easy for four-probe resistance measurement. Factors such as the energy and wavelength of the laser will affect the generation efficiency and quantity of carriers. Therefore, the selection of the laser should be based on the characteristics of the material to be measured. Based on the current experimental data, lasers with wavelengths between 200 nm and 300 nm are suitable for most third-generation semiconductors or wide-bandgap semiconductors and high-resistance epitaxy.

[0068] Generally speaking, the principle of generating carriers by laser irradiating a semiconductor is to provide energy to cause electrons to transition to the conduction band, and at the same time generate holes, forming electron-hole pairs, thereby improving the contact characteristics and realizing stable four-probe measurement.

[0069] If the wafer is irradiated with laser over a large area, the generated carriers will exist throughout the entire surface, resulting in inaccurate measurement results. The laser in this embodiment is only irradiated on the small area where the probe is located (the effective action area of the laser is the probe channel), which can make the measurement results more accurate.

[0070] Embodiment 2

[0071] This embodiment provides a method for a four-probe measuring instrument to measure a wafer to be measured. Using the four-probe measuring instrument of Embodiment 1, this method includes:

[0072] Placing the wafer on the test platform;

[0073] Making physical contact between the probes of the four-probe measuring instrument and the surface of the wafer;

[0074] Irradiating the contact surface between the probe and the wafer with laser;

[0075] Apply a current to two of the needles of the four-probe measuring instrument and measure the voltage drop between the other two needles.

[0076] Based on the measured current and voltage values, the sheet resistance of the wafer surface can be calculated using the corresponding formula. To improve the measurement accuracy, multiple measurements are usually taken at different positions on the wafer surface and the average value is taken.

[0077] Example 3

[0078] This embodiment provides a four-probe measurement system, including the four-probe measuring instrument of Embodiment 1, and further including a soft breakdown circuit structure, where the soft breakdown circuit structure is used to be connected to the four-probe measuring instrument during measurement; the soft breakdown circuit structure includes:

[0079] A capacitor, one end of the capacitor is grounded, and the other end is connected to a charging circuit and a discharging circuit;

[0080] The charging circuit is used to charge the capacitor; the charging circuit includes multiple parallel charging branches, and each charging branch includes a first switch for controlling the connection or disconnection of the current branch; the electric energy provided by each charging branch is different;

[0081] The discharging circuit is used to discharge the capacitor; the discharging circuit includes four parallel discharging branches, each discharging branch is connected to one probe of the four-probe measuring instrument, and each discharging branch includes a second switch for controlling the connection or disconnection of the current branch.

[0082] Specifically, referring to Figure 7 , the charging circuit is used to charge the capacitor C. The charging circuit includes multiple parallel charging branches. Each charging branch includes a voltage source, the negative terminal of the voltage source is grounded, the positive terminal is connected to a resistor R1, the other end of the resistor R1 is connected to the first switch (the first switches of multiple branches are S1, S2, S3, Sn respectively), and the other end of the first switch is connected to the capacitor C; the voltage sources of different charging branches provide different voltages. Figure 5 The voltages provided by the four voltage sources in are 15V, 10V, 5V, and 0.1V respectively. Multiple charging branches can be set to provide different voltages to adapt to more wafers to be measured with different properties.

[0083] The discharge circuit includes four parallel discharge branches, each discharge branch is connected to one probe of the four-probe measuring instrument, and each of the discharge branches includes a second switch (the second switches on the four discharge branches are SP1, SP2, SP3, and SP4 respectively) for controlling the connection or disconnection of the current branch. Specifically, in this embodiment, the discharge circuit includes: a control switch Son, connected to the capacitor C; a resistor R, connected to the other end of the control switch Son; and the four parallel discharge branches are connected to the other end of the resistor R.

[0084] The form of the charging circuit can be various. Refer to Figure 8 , each charging branch includes a current source, the negative extreme of the current source is grounded, the positive extreme is connected with a first resistor, the other end of the first resistor R1 is connected to the first switch (the first switches of the four branches are S1, S2, S3, and Sn respectively), the other end of the first switch is connected to the capacitor C, and a second resistor R2 is also connected between the positive extreme and the negative extreme of the current source; the current sources of different charging branches provide different currents (the currents provided by the four current sources are 100 mA, 10 mA, 1 mA, and 0.01 A respectively).

[0085] Refer to Figure 9 , the charging circuit includes: a transformer T; a plurality of series-connected voltage-dividing resistors, connected between the transformer T and the reference ground; and a plurality of the charging branches are connected between different voltage-dividing resistors. It can be boosted to a set voltage value (such as 100 V) through the transformer T, and then voltage division is performed through the series-connected voltage-dividing resistors so that each charging branch has a different voltage value.

[0086] In this embodiment, according to the properties of the wafer to be measured, a charging branch with suitable energy is selected to charge the capacitor, and then the capacitor is discharged. The silicon wafer is subjected to soft breakdown through the probe, which can form a good ohmic contact between the probe and the surface of the silicon wafer to be measured and improve the stability of silicon wafer measurement. The energy for charging the capacitor is 1 / 2CU 2 , and the silicon wafer is subjected to soft breakdown by discharging the capacitor, which will not cause harm to the silicon wafer. If directly powered on, it may cause harm to the silicon wafer. The forms of the charging circuit and the discharge circuit of the capacitor can be various as long as the capacitor can be charged and discharged.

[0087] Embodiment 4

[0088] This embodiment provides a method for measuring a silicon wafer to be measured by a four-probe measurement system. Using the four-probe measurement system of Embodiment 3, this method includes:

[0089] Connect the soft breakdown circuit structure to the four-probe measuring instrument for circuit connection;

[0090] Place the four probes of the four-probe measuring instrument on the silicon wafer to be measured;

[0091] According to the properties of the silicon wafer to be measured, select one of the charging branches of the charging circuit to charge the capacitor, and then select one of the discharging branches to discharge the capacitor;

[0092] Repeat the above steps until the four probes have all completed a process of capacitor discharge;

[0093] After that, measure the silicon wafer with the four-probe measuring instrument.

[0094] Normally, when measuring a silicon wafer, the same charging branch can be used for the four charging processes. Multiple charging branches are used to adapt to different silicon wafers.

[0095] Before measuring the silicon wafer in this embodiment, soft breakdown is first performed on the silicon wafer to form a good ohmic contact between the probe and the surface of the silicon wafer to be measured, so as to improve the stability of silicon wafer measurement.

[0096] The method of this embodiment is applicable to the case where there is an oxide layer on the silicon wafer to be measured. The method of Embodiment 2 is applicable to the case where there is no oxide layer on the silicon wafer to be measured or the oxide layer has been punctured by the probe. Embodiment 2 does not use a soft breakdown circuit.

[0097] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention according to the above disclosure are within the protection scope of the claims.

Claims

1. A four-probe measuring instrument, characterized in that: include: Four probes, each probe having a channel passing through from top to bottom; A laser emitter, wherein the laser emitted by the laser emitter passes through the channel from top to bottom; when measuring, the probe is physically contacted with the surface of the wafer, and the contact surface between the probe and the wafer is irradiated with laser, so that electrons are transferred to the conduction band, holes are generated at the same time, and electron-hole pairs are formed, thereby improving contact characteristics; A fixing plate, wherein the fixing plate has a hole opposite to the probe, the probe passes through the hole, and the fixing plate is used to fix the probe and block the laser outside the probe from irradiating the wafer to be tested.

2. The four-probe measuring instrument according to claim 1, characterized in that: The four-probe measuring instrument also includes: The host computer, control denoising module and preamplifier are connected in sequence; The host computer sends an acquisition command to the control denoising module and controls the switching frequency of the laser transmitter; The control denoising module controls the operation of the preamplifier according to the acquisition instruction of the host computer; The preamplifier is connected to the probes of the four-probe measuring instrument, and is used to apply current to two of the probes according to the acquisition instruction, and receive the voltage drop of the other two probes; and transmit the voltage signal to the control denoising module; The control denoising module amplifies the voltage signal and operates it with the switching frequency of the laser transmitter to suppress noise that is out of frequency or out of phase with the switching frequency of the laser transmitter, and then converts the voltage signal into a digital signal and sends it to the host computer.

3. The four-probe measuring instrument according to claim 1, characterized in that: The number of the channels is one or more.

4. A four-probe measurement system, characterized in that: A four-probe measuring instrument according to any one of claims 1 to 3, further comprising a soft breakdown circuit structure, wherein the soft breakdown circuit structure is used to be connected to the four-probe measuring instrument during measurement; The soft breakdown circuit structure comprises: A capacitor, one end of which is grounded, and the other end of which is connected to a charging circuit and a discharging circuit; The charging circuit is used to charge the capacitor; the charging circuit includes a plurality of charging branches connected in parallel, each of the charging branches includes a first switch that controls the connection or disconnection of the current branch; the electric energy provided by each charging branch is different; The discharge circuit is used to discharge the capacitor; the discharge circuit includes four discharge branches connected in parallel, each of which is connected to a probe of the four-probe measuring instrument, and each of which includes a second switch for controlling the connection or disconnection of the current branch.

5. The four-probe measurement system according to claim 4, characterized in that: Each of the charging branches includes a voltage source, a negative terminal of the voltage source is grounded, a positive terminal is connected to a resistor, the other end of the resistor is connected to the first switch, and the other end of the first switch is connected to the capacitor; the voltage sources of different charging branches provide different voltages.

6. The four-probe measurement system according to claim 4, characterized in that: Each of the charging branches includes a current source, a negative terminal of the current source is grounded, a positive terminal is connected to a first resistor, the other end of the first resistor is connected to the first switch, the other end of the first switch is connected to the capacitor, and a second resistor is connected between the positive and negative terminals of the current source; the current sources of different charging branches provide different currents.

7. The four-probe measurement system according to claim 4, characterized in that: The charging circuit comprises: transformer; A plurality of voltage-dividing resistors connected in series, connected between the transformer and a reference ground; A plurality of the charging branches are connected between different voltage-dividing resistors.

8. The four-probe measurement system according to claim 4, characterized in that: The discharge circuit comprises: A control switch connected to the capacitor; a resistor connected to the other end of the control switch; The four parallel discharge branches are connected to the other end of the resistor.

9. A method for measuring a wafer to be tested using a four-probe measuring instrument, characterized in that: Using the four-probe measuring instrument according to any one of claims 1 to 3, the method comprises: placing the wafer on a test platform; Probes of the four-probe measuring instrument are brought into physical contact with a surface of a wafer; irradiating the contact surface between the probe and the wafer with a laser; Current is applied to two of the needles of the four-probe meter, and the voltage drop between the other two needles is measured.

10. The method for measuring a wafer to be tested by a four-probe measuring instrument as claimed in claim 9, characterized in that: When the contact surface between the probe and the wafer is irradiated with laser, the laser is irradiated at a set frequency or continuously.

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