TWM665083U - Wafer impedance measuring system - Google Patents

Abstract

The wafer impedance measuring system includes a carrier, a probe, a probe driving and measuring mechanism, and a controller. The probe moves downward to correspond to a predetermined touching position of a to-be-measured point. The probe conducts a measurement for the to-be-measured point to generate a plurality of measuring values. A probe driving and measuring module judges the measuring values. If all of the measuring values are not constant, the probe moves downward at a first velocity. If at least one of the measuring values is not constant, the probe moves upward at the first velocity and then moves downward at a second velocity. If all of the measuring values are constant but do not fall into a first product range, the probe moves downward at the second velocity. If at least one of the measuring values falls into both of the first product range and a second product range, a measuring result is output. Therefore, the accuracy is increased.

Description

Wafer Impedance Measurement System

The invention relates to a measurement system, and in particular to a wafer impedance measurement system.

When measuring a general wafer, each measurement must rely on the inspector to manually control the probe to touch the test point. In addition to the problem of inaccurate measurement position leading to incorrect measurement results, the manual measurement method also consumes a lot of time and manpower. In addition, when measuring wafers with extremely small die sizes, manual measurement cannot ensure the accuracy of wafer impedance measurement.

Although some manufacturers have developed a method to automatically measure wafers with a probe, the depth of the probe penetrating the wafer cannot be accurately controlled during measurement, resulting in reduced measurement accuracy, so there is still room for improvement.

In order to solve the above problems, the present invention provides a wafer impedance measurement system, which can effectively control the depth of the probe penetrating into the wafer through the configuration of the system architecture, thereby improving the measurement efficiency and measurement accuracy.

According to an embodiment of the present invention, a wafer impedance measurement system is provided, comprising a carrier, at least one probe, a probe driving and measuring mechanism, and a controller. The carrier is used to carry a wafer. The at least one probe is located above the carrier and is used to contact at least one point to be measured on the wafer. The probe driving and measuring mechanism is connected to the at least one probe to drive the at least one probe to move, and the probe driving and measuring mechanism enables the at least one probe to measure the wafer. The controller is electrically connected to the probe driving and measuring mechanism and includes a probe control and measuring module. The probe control and measuring module is used to drive the probe driving and measuring mechanism to drive the at least one probe to move vertically downward to a preset contact position corresponding to the at least one point to be measured, and to make the probe measure the at least one point to be measured to generate a plurality of measurement values. The probe control and measuring module determines the plurality of measurement values. If the plurality of measurement values are not constant, the probe control and measuring module drives the probe driving and measuring mechanism to drive the at least one probe to move vertically downward at a first rate until at least one of the updated plurality of measurement values is constant. If at least one of the plurality of measurement values is is not a constant, the probe control and measurement module drives the probe driving and measurement mechanism to drive the at least one probe to move vertically upward at a first rate for an ascending distance and then downward at a second rate for a first descending distance, until the updated plurality of measurement values are all constants; if the plurality of measurement values are all constants but do not fall into a first product range, the probe control and measurement module drives the probe driving and measurement mechanism to drive the at least one probe to move vertically downward at a second rate for a second descending distance, until at least one of the updated plurality of measurement values falls into the first product range; and if at least one of the plurality of measurement values falls into the first product range and falls into a second product range, a measurement result is output.

Thus, by moving the probe to penetrate the wafer and adjusting the probe movement speed and distance when different measurement values are measured, the depth of the probe penetrating the wafer can be accurately controlled, thereby improving measurement efficiency and measurement accuracy.

According to the wafer impedance measurement system of the aforementioned implementation method, the number of the aforementioned at least one probe can be four and divided into two applicators and two sensors. If at least one of the aforementioned multiple measurement values falls within the first product range but does not fall within the second product range, the probe control and measurement module drives the probe drive and measurement mechanism to drive the two sensors to move vertically downward by a third descent distance at a third rate. If at least one of the updated aforementioned multiple measurement values falls within the second product range, the measurement result is output; if none of the updated aforementioned multiple measurement values fall within the second product range, the probe control and measurement module drives the probe drive and measurement mechanism to drive the two applicators to move vertically downward by a third descent distance at a third rate, then updates the aforementioned multiple measurement values, and outputs the measurement result.

In the wafer impedance measurement system according to the aforementioned implementation method, the first rate may be greater than the second rate.

In the wafer impedance measurement system according to the aforementioned implementation method, the rising distance may be smaller than the first falling distance, and the second falling distance may be smaller than the first falling distance.

The wafer impedance measurement system according to the above-mentioned implementation method may further include a carrier driving mechanism connected to the carrier to drive the carrier to move. The controller further includes a carrier control module, which is electrically connected to the carrier driving mechanism.

The following will describe the embodiments of the present invention with reference to the drawings. For the sake of clarity, many practical details will be described together in the following description. However, the reader should understand that these practical details should not be used to limit the present invention. That is to say, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some commonly known structures and components will be shown in the drawings in a simple schematic manner; and repeated components may be represented by the same number or similar number.

In addition, the terms "first", "second", "third", etc. in this article are only used to describe different elements or components, and do not limit the elements/components themselves. Therefore, the first element/component can also be renamed as the second element/component. Moreover, the combination of elements/components/mechanisms/modules in this article is not a generally known, conventional or familiar combination in this field. Whether the elements/components/mechanisms/modules themselves are known cannot be used to determine whether their combination relationship is easy to be completed by ordinary knowledge in the technical field.

Please refer to FIG. 1 , which shows a system block diagram of a wafer impedance measurement system 100 according to an embodiment of the present invention. The wafer impedance measurement system 100 includes a carrier 160 , at least one probe 140 , a probe driving and measuring mechanism 150 , and a controller 110 .

The carrier 160 is used to carry a wafer. The at least one probe 140 is located above the carrier 160 and is used to contact at least one test point on the wafer (such as the test point P in FIG. 5 ). In this embodiment, the number of the probe 140 and the test point is four, but it is not limited thereto.

The probe driving and measuring mechanism 150 is connected to the four probes 140 to drive the four probes 140 to move, and the probe driving and measuring mechanism 150 enables the four probes 140 to measure the wafer.

The controller 110 is electrically connected to the probe driving and measuring mechanism 150 and includes a probe control and measuring module 113. The probe control and measuring module 113 is used to drive the probe driving and measuring mechanism 150 to drive the four probes 140 to move vertically downward to a preset contact position corresponding to the four test points, and to make the probes 140 measure the four test points to generate a plurality of measurement values. The probe control and measuring module 113 determines the aforementioned plurality of measurement values. If the aforementioned plurality of measurement values are not constant, the probe control and measuring module 113 drives the probe driving and measuring mechanism 150 to drive the four probes 140 to move vertically downward at a first rate until at least one of the updated aforementioned plurality of measurement values is constant. If the aforementioned plurality of measurement values are not constant, the probe control and measuring module 113 drives the probe driving and measuring mechanism 150 to drive the four probes 140 to move vertically downward at a first rate until at least one of the updated aforementioned plurality of measurement values is constant. If the least one of the above-mentioned multiple measurement values is not a constant, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 to move vertically upward for an ascending distance at a first rate and then move downward for a first descending distance at a second rate, until the updated aforementioned multiple measurement values are all constants; if the aforementioned multiple measurement values are all constants but none of them fall into a first product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 to move vertically downward for a second descending distance at a second rate, until at least one of the updated aforementioned multiple measurement values falls into the first product range; and if at least one of the aforementioned multiple measurement values falls into the first product range and falls into a second product range, a measurement result is output.

Thus, by moving the probe 140 to penetrate the wafer and adjusting the moving speed and distance of the probe 140 when different measurement values are measured, the penetration depth of the probe 140 into the wafer can be accurately controlled, thereby improving the measurement efficiency and measurement accuracy.

The carrier 160 may include a plane for placing the wafer, and the probe driving and measuring mechanism 150 may be used to drive the probe 140 to move horizontally or vertically relative to the wafer so as to be aligned with the point to be measured. In this embodiment, the wafer impedance measurement system 100 may further include a carrier driving mechanism 120, which is connected to the carrier 160 to drive the carrier 160 to move, and the controller 110 may further include a carrier control module 111, and the carrier control module 111 is electrically connected to the carrier driving mechanism 120. In other words, in addition to the probe driving and measuring mechanism 150 being able to drive the probe 140 to move, the carrier driving mechanism 120 can also drive the carrier 160 to move, such as vertically, so that the relative position of the wafer and the probe 140 can be moved more conveniently. The probe drive and measurement mechanism 150 may further include a height measuring device such as an optical ruler, so as to accurately control the moving distance of the probe 140. The controller 110 may be a processor, a microprocessor, a central processing unit (CPU), a computer, a wafer inspection machine processor, a mobile device processor, a cloud processor or other electronic computing processor, and may be programmed to achieve the functions of each module.

When measuring the wafer impedance, a preset descending distance may be stored in the controller 110. When the probe 140 has moved to the top of the point to be tested (i.e., the test position, at which time the horizontal coordinates of the probe 140 and the point to be tested are the same), the probe control and measurement module 113 may drive the probe drive and measurement mechanism 150 to drive the probe 140 to move vertically downward by a preset distance, and then reach the preset contact position. In an ideal state, the probe 140 will contact the wafer at this time and can be measured. However, different wafers may have different thicknesses, which may cause the probe 140 to not contact the wafer. Therefore, the displacement of the probe 140 may be further controlled by determining the measured value.

In detail, the probe 140 can obtain multiple measurement values at the same position. If these measurement values are not constants but are all infinite, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 vertically downward at a first rate, and performs a measurement every 5 μm of descent. If the measurement values obtained are all infinite, it means that the test point has not been touched or pierced. If at least one of the newly obtained measurement values is a constant but not all are constants, it means that the test point may be touched or pierced, but the measurement is unstable. Therefore, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 to move up at a first rate and then move down at a second rate to re-obtain the measurement value.

In this embodiment, the first rate can be greater than the second rate. The first rate can be, for example, 10 mm/s, and the second rate can be, for example, 5 mm/s. In this way, it can be helpful to move at a faster rate when the test point has not yet been touched or pierced, which helps to pierce the test point. When the test point may be touched or pierced, the second rate can be used to slowly move downward to avoid causing damage to the wafer. In addition, the rising distance can be less than the first falling distance. The rising distance can be, for example, 5 μm, and the first falling distance can be (1+rising distance)/2, which is 3 μm, but it is not limited to this.

When the measured values are all constant but do not fall within the first product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 to descend the second descent distance at a second rate. For example, if the product specification is 3 μΩ, the first product range may be, for example, 2 μΩ to 5 μΩ. When comparing whether the measured values fall within the first product range, any one of the measured values or the median may be used for judgment. If the median of the measured values falls within the first product range, it is determined that this condition is met. If the measured values are all constant but do not fall within the first product range or the median of the measured values does not fall within the first product range, the second descent distance may continue to be descended until the condition is met. The second drop distance may be smaller than the first drop distance, and the second drop distance may be, for example, 2.5 μm. In other embodiments, it may be set that when the second drop distance is dropped a certain number of times and the measured values do not fall within the first product range, the measurement is determined to be a failure.

The four probes 140 can be divided into two applicators and two sensors. If at least one of the aforementioned multiple measurement values falls within the first product range but does not fall within the second product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the two sensors to move vertically downward by a third descent distance at a third rate. If at least one of the updated aforementioned multiple measurement values falls within the second product range, the measurement result is output; if none of the updated aforementioned multiple measurement values fall within the second product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the two applicators to move vertically downward by a third descent distance at a third rate, then updates the aforementioned multiple measurement values, and outputs the measurement result.

More specifically, wafers that meet product specifications can be further differentiated through measurement. Therefore, if the product specification is 3 μΩ, the first product range is 2 μΩ to 5 μΩ, and the second product range can be set to 3 μΩ to 4 μΩ or 2.5 μΩ to 3.5 μΩ to further differentiate wafers with better standards and quality.

In this embodiment, the four-probe method is used to measure the resistance, so the two applicators of the four probes 140 refer to high potential application (force High) and low potential application (force Low), and the two sensors refer to high potential sensing (sense High) and low potential sensing (sense Low). Since the depth of the two sensors has a greater impact on the measurement result, the two sensors can be moved first, and at this time, the third moving rate can be slower than the second rate, so the third rate can be 2 mm/s, and the third descent distance can be 2 μm, but it is not limited to this. After re-obtaining the measured value, if any of the measured values falls into the second product range, the value can be rounded up.

On the contrary, if the condition is not met, the two applicators are allowed to descend the third descending distance at the third rate. At this time, regardless of whether they fall into the second product range, the value is thrown up. It should be particularly noted that the two sensors and the two applicators can be descended only once or multiple times, depending on the needs.

Furthermore, as shown in FIG. 1 , the wafer impedance measurement system 100 may further include an image capture mechanism 130, and the controller 110 may further include an image control module 112. The image control module 112 may control the image capture mechanism 130 to capture an image frame of the wafer and analyze the image frame. The image capture mechanism 130 may be a charge coupled device (CCD) camera, but is not limited thereto.

Please refer to FIG. 2 and FIG. 3, and refer to FIG. 1 together, wherein FIG. 2 shows a block flow chart of a wafer impedance measurement method S100 according to another embodiment of the present invention, and FIG. 3 shows a step flow chart of the wafer impedance measurement method S100 of the embodiment of FIG. 2. The wafer impedance measurement method S100 includes a probe horizontal movement step S140, an initial probe lowering step S150, and a measurement and probe lowering adjustment step S160. The details of the wafer impedance measurement method S100 will be described below in conjunction with the wafer impedance measurement system 100 of FIG. 1.

In the probe horizontal movement step S140, the probe control and measurement module 113 of the controller 110 drives the probe driving and measurement mechanism 150 to move the probe 140 horizontally, corresponding to at least one test position of the test point P of the wafer (shown in Figure 5). The test position at this time means that the horizontal coordinates of the probe 140 and the test point P are the same.

In the initial probe lowering step S150, the probe control and measurement module 113 drives the probe driving and measurement mechanism 150 to move the four probes 140 vertically downward to the preset contact positions corresponding to the four test points P. The preset contact positions are pre-set according to the thickness of the wafer specification and may not actually contact the wafer.

In the measurement and probe adjustment step S160, the probe control and measurement module 113 causes the four probes 140 to measure the four test points P to generate a plurality of measurement values, and determines the plurality of measurement values. If the plurality of measurement values are not constant, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 vertically downward at a first rate until at least one of the updated plurality of measurement values is constant. If at least one of the plurality of measurement values is not constant, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 vertically downward at a first rate. The probe 140 moves vertically upward for an ascending distance at a first rate and then moves downward for a first descending distance at a second rate until the updated plurality of measurement values are all constants; if the updated plurality of measurement values are all constants but do not fall within the first product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the four probes 140 to move vertically downward for a second descending distance at a second rate until at least one of the updated plurality of measurement values falls within the first product range; and if at least one of the plurality of measurement values falls within the first product range and falls within the second product range, the measurement result is output.

In addition, the four probes 140 can be divided into two applicators and two sensors. In the measurement and needle lowering adjustment step S160, if at least one of the aforementioned multiple measurement values falls within the first product range but does not fall within the second product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the two sensors to move vertically downward at a third rate for a third descent distance. If at least one of the updated aforementioned multiple measurement values falls within the second product range, the measurement result is output; if none of the updated aforementioned multiple measurement values fall within the second product range, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the two applicators to move vertically downward at a third rate for a third descent distance, then updates the aforementioned multiple measurement values, and outputs the measurement result.

That is, when measuring wafer resistance, the probe control and measurement module 113 allows the probe driving and measurement mechanism 150 to drive the probe 140 to descend or ascend at different speeds and different distances, so as to adjust the depth of the probe 140 and obtain more accurate measurement values.

Therefore, in the probe horizontal movement step S140, the horizontal position of the probe 140 is first positioned. In the initial needle lowering step S150, it can first be lowered to a preset contact position. After that, the measurement and needle lowering adjustment step S160 can be entered.

As shown in FIG. 3 , in step S01, the probe control and measurement module 113 of the controller 110 obtains multiple measurement values corresponding to the preset contact position, and enters step S02 to determine whether the measurement values are all infinite. If so, it enters step S03, the probe 140 moves vertically downward at a first speed, re-measures and enters step S02 for determination again.

On the contrary, if at least one of the measured values is not infinite in step S02, the process proceeds to step S04 to determine whether the measured values are all constants. If not, the process proceeds to step S05, where the probe 140 first moves vertically upwards by an ascending distance at a first rate, and then proceeds to step S06, where the probe 140 moves vertically downwards by a first descending distance at a second rate, and then remeasures and proceeds to step S04 for determination.

If step S04 determines that the measured values are all constants, then proceed to step S07 to determine whether at least one of the measured values falls within the first product range. If not, proceed to step S08, where the probe 140 moves vertically downward a second descent distance at a second rate, remeasures, and then proceeds to step S07 for determination.

If step S07 determines that at least one of the measured values falls within the first product range, the process proceeds to step S09 to determine whether at least one of the measured values falls within the second product range. If so, the process proceeds to step S13 to take a value upcast. If not, the process proceeds to step S10, the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the two sensors to move vertically downward at a third rate for a third descending distance, re-measures, and proceeds to step S11 to determine whether at least one of the measured values falls within the second product range. If so, the process proceeds to step S13 to take a value upcast. If not, the process proceeds to step S12, where the probe control and measurement module 113 drives the probe drive and measurement mechanism 150 to drive the two applicators to move vertically downward a third descending distance at a third rate, re-measure, and take the value of the upward throw in step S13.

Please refer to Figures 4, 5 and 6, and also refer to Figures 2 and 3, wherein Figure 4 is a schematic diagram of a positioning point A1, A2 and a cutting line L in an image frame of the wafer impedance measurement method S100 of the embodiment of Figure 2, Figure 5 is a schematic diagram of a point to be measured P in the image frame of the embodiment of Figure 2, and Figure 6 is a schematic diagram of impedance measurement in the image frame of the embodiment of Figure 2. The wafer impedance measurement method S100 may further include a first positioning step S120 and a second positioning step S130.

In the first positioning step S120, the carrier control module 111 of the controller 110 drives the carrier driving mechanism 120 to move the carrier 160 carrying the wafer, and the image control module 112 of the controller 110 enables the image capture mechanism 130 to photograph the wafer to obtain an image frame including an initial positioning point D of the wafer. The controller 110 also stores an initial positioning point position of the carrier driving mechanism 120. In the second positioning step S130, the carrier control module 111 drives the carrier driving mechanism 120 to move the wafer so that the four test points P adjacent to the initial positioning point D are aligned with the image capture mechanism 130, and the controller 110 stores a relative position corresponding to the carrier driving mechanism 120 and four test positions of the four test points P corresponding to the four probes 140. The first positioning step S120 and the second positioning step S130 are performed before the probe horizontal movement step S140.

The wafer impedance measurement method S100 may further include a wafer angle correction step S110, wherein the controller 110 may enable the carrier driving mechanism 120 to drive the wafer to move, so that the cutting path L of the wafer is aligned with the image capture mechanism 130, and two positioning points A1 and A2 are established according to the cutting path L, and the angle positioning of the wafer is completed by the two positioning points A1 and A2.

Specifically, the image capture mechanism 130 can align the wafer and capture the image frame, and the image control module 112 can further analyze the image frame. Therefore, as shown in FIG. 4, in the wafer angle correction step S110, the controller 110 establishes the image frame including the cross-shaped cutting road L as the region of interest (ROI) image, and simultaneously establishes positioning points A1 and A2 in the ROI image, and stores the XY axis values of the positioning points A1 and A2. The controller 110 can subsequently automatically perform compensation correction according to the X axis values of the positioning points A1 and A2 to further complete the wafer angle correction.

As shown in FIG. 5 , in the first positioning step S120, the controller 110 enables the carrier driving mechanism 120 to drive the wafer to move so that the initial positioning point D in the plurality of dies of the wafer can be captured in the image frame by the image capture mechanism 130 to store the initial positioning point position corresponding to the carrier 160. The initial positioning point D is located on one side of the cutting path L of the wafer. In the second positioning step S130, the controller 110 can align the image frame with the test point P adjacent to the initial positioning point D to store a relative position corresponding to the carrier driving mechanism 120 and a test position corresponding to the test point P. The test point P is a point preset by the user to be measured, and the test point P can be located on the die or on a flat surface between the die.

Thus, by first recording the initial positioning point position through the first positioning step S120 and then recording the relative position through the second positioning step S130, the point to be measured P can be positioned a second time, thereby increasing the positioning accuracy of the carrier 160, making the subsequent needle placement position more accurate, and thus ensuring the accuracy of subsequent measurements.

After the second positioning step S130, the probe horizontal movement step S140, the initial needle insertion step S150 and the measurement and needle insertion adjustment step S160 can be performed, as shown in FIG. 6, to measure the point P to be measured.

Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined in the attached patent application.

100: Wafer impedance measurement system 110: Controller 111: Carrier control module 112: Image control module 113: Probe control and measurement module 120: Carrier drive mechanism 130: Image capture mechanism 140: Probe 150: Probe drive and measurement mechanism 160: Carrier A1, A2: Positioning point D: Initial positioning point L: Cutting path P: Point to be measured S100: Wafer impedance measurement method S110: Wafer angle correction step S120: First positioning step S130: Second positioning step S140: Probe horizontal movement step S150: Initial probe placement step S160: Measurement and probe placement adjustment step S01,S02,S03,S04,S05,S06,S07,S08,S09,S10,S11,S12,S13: Steps

FIG. 1 shows a system block diagram of a wafer impedance measurement system according to an embodiment of the present invention; FIG. 2 shows a block flow chart of a wafer impedance measurement method according to another embodiment of the present invention; FIG. 3 shows a step flow chart of the wafer impedance measurement method of the embodiment of FIG. 2; FIG. 4 shows a schematic diagram of a positioning point and a cutting path in an image screen of the wafer impedance measurement method of the embodiment of FIG. 2; FIG. 5 shows a schematic diagram of a point to be measured in the image screen of the embodiment of FIG. 2; and FIG. 6 shows a schematic diagram of impedance measurement in the image screen of the embodiment of FIG. 2.

100: Wafer impedance measurement system

110: Controller

111: Carrier control module

112: Image control module

113: Probe control and measurement module

120: Carrier driving mechanism

130: Image capture mechanism

140:Probe

150: Probe drive and measurement mechanism

160:Carrying parts

Claims (5)

A wafer impedance measurement system comprises: a carrier for carrying a wafer; at least one probe located above the carrier and used to contact at least one point to be measured on the wafer; a probe driving and measuring mechanism connected to the at least one probe to drive the at least one probe to move, and the probe driving and measuring mechanism enables the at least one probe to measure the wafer; and A controller electrically connected to the probe driving and measuring mechanism and including a probe control and measuring module, the probe control and measuring module is used to drive the probe driving and measuring mechanism to drive the at least one probe to move vertically downward to a preset contact position corresponding to the at least one point to be measured, and to make the probe measure the at least one point to be measured to generate a plurality of measurement values, and the probe control and measuring module judges the measurement values, wherein: If the measurement values are not constant, the probe control and measuring module drives the probe driving and measuring mechanism to drive the at least one probe vertically downward at a first rate until at least one of the updated measurement values is a constant; If at least one of the measured values is not a constant, the probe control and measurement module drives the probe drive and measurement mechanism to drive the at least one probe to move vertically upward at the first rate for an ascending distance and then downward at a second rate for a first descending distance until the updated measured values are all constants; If the measured values are all constants but do not fall into a first product range, the probe control and measurement module drives the probe drive and measurement mechanism to drive the at least one probe to move vertically downward at the second rate for a second descending distance until at least one of the updated measured values falls into the first product range; and If at least one of the measured values falls into the first product range and falls into a second product range, a measurement result is output. A wafer impedance measurement system as described in claim 1, wherein the number of the at least one probe is four and is divided into two applicators and two sensors. If at least one of the measurement values falls within the first product range but does not fall within the second product range, the probe control and measurement module drives the probe drive and measurement mechanism to drive the two sensors to move vertically downward by a third descent distance at a third rate. If at least one of the updated measurement values falls within the second product range, the measurement result is output; if none of the updated measurement values fall within the second product range, the probe control and measurement module drives the probe drive and measurement mechanism to drive the two applicators to move vertically downward by the third descent distance at the third rate, then updates the measurement values, and outputs the measurement result. A wafer impedance measurement system as described in claim 1, wherein the first rate is greater than the second rate. A wafer impedance measurement system as described in claim 1, wherein the rising distance is smaller than the first falling distance, and the second falling distance is smaller than the first falling distance. The wafer impedance measurement system as described in claim 1 further comprises: A carrier driving mechanism connected to the carrier to drive the carrier to move; Wherein, the controller further comprises a carrier control module, and the carrier control module is electrically connected to the carrier driving mechanism.