Laser cleaning energy debugging method and wafer measuring device

Abstract

The invention provides a debugging method of laser cleaning energy, which comprises the following steps of: firstly, providing a first optical signal and a second optical signal for a reference wafer, so that the positions of a first light spot and a second light spot coincide, and confirming that the second light spot is qualified; secondly, replacing the reference wafer with a to-be-detected wafer, setting n detection points on the to-be-detected wafer, setting n energy values for the second optical signal, measuring the first thickness of the n detection points before cleaning, cleaning the n detection points in a one-to-one correspondence manner according to the n energy values of the second optical signal, and measuring the second thickness of the n detection points after cleaning; and finally, performing one-to-one correspondence difference on the first thickness and the second thickness, establishing a first function about the n energy values and the n thickness differences, and obtaining an optimal energy value. The invention further provides a wafer measuring device which comprises a measuring module, a cleaning module and imaging equipment. The measuring module is used for measuring the thickness of the wafer; the cleaning module is used for cleaning the wafer; the imaging device is used for observing light spots formed on the wafer.

Description

Technical Field

[0001] This invention relates to the field of optical calibration, and in particular to a method for calibrating laser cleaning energy and a wafer measurement device. Background Technology

[0002] In the semiconductor device manufacturing process, because the film thickness in the front-end process is very thin, it is very easy for AMC (Airborne Molecular Contamination) to adhere to it. Moreover, the presence of AMC will seriously affect the subsequent film measurement results, and incorrect measurement results will seriously affect the product yield.

[0003] Therefore, the industry typically uses wafer heating to remove AMCs. However, the overall wafer heating process is complex. Consequently, major flow measurement equipment manufacturers both domestically and internationally employ laser-based individual heating of the measurement points to remove AMCs, a process known as laser cleaning. During laser cleaning, if the energy is too low, it will not be effective; if the energy is too high, it will damage the product. Therefore, accurately selecting the cleaning energy is extremely important for laser cleaning. Furthermore, with the continuous development of semiconductor technology, the size of measurement pads is becoming increasingly smaller (within 40µm), placing extremely high demands on the alignment accuracy of laser cleaning equipment.

[0004] Therefore, in the case of wafer measurement devices containing many optical modules, how to achieve the accuracy of the laser cleaning module within the wafer measurement device and the consistency between different wafer measurement devices has become one of the technical problems that urgently need to be solved by those skilled in the art.

[0005] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for adjusting laser cleaning energy and a wafer measurement device to solve the problems of complex assembly and adjustment of laser cleaning modules, inconsistent selection of cleaning energy, and inability to accurately select cleaning energy in the prior art.

[0007] To achieve the above and other related objectives, the present invention provides a method for adjusting laser cleaning energy. The method includes at least the following steps: S1: A first optical signal is incident obliquely from one side of a reference wafer, and a second optical signal is incident perpendicularly from directly above the reference wafer; S2: The first optical signal forms a first spot at a reference point on the reference wafer, and the second optical signal forms a second spot at the reference point; the positions of the first spot and the second spot are aligned, and the second spot is confirmed to be qualified; S3: The reference wafer is replaced with a wafer to be tested; n detection points are set on the wafer to be tested, and n incremental energy values ​​are set for the second optical signal, where n is a natural number greater than or equal to 2; the first thickness before cleaning is measured based on the first optical signal at the n detection points, and the n detection points are cleaned one-to-one based on the n energy values ​​of the second optical signal; then, the second thickness after cleaning is measured based on the first optical signal at the n detection points; S4: The first thickness and the second thickness are subtracted one-to-one to establish a first function about the n energy values ​​and the n thickness differences, and the optimal energy value for wafer cleaning is obtained based on the first function.

[0008] Optionally, before step S2, there is a step S2', in which the first coordinates of the reference point are obtained based on the first optical signal, and the first coordinates are calibrated when there is a deviation between the first coordinates and the reference coordinates.

[0009] Optionally, in step S2, an imaging device is provided directly above the reference wafer to move the images of the first light spot and the second light spot to the target field of view of the imaging device so as to overlap the first light spot and the second light spot.

[0010] Alternatively, in step S2, the first light spot is first moved to the target field of view by adjusting the position of the reference wafer; then, the second light spot is moved to the target field of view by adjusting the position of the light source that generates the second light signal.

[0011] Optionally, in step S2, the qualification evaluation parameters of the second spot are any one or a combination of two or more of the following: the integrity of the second spot, energy, and ablation size.

[0012] Optionally, in step S4, the slope between adjacent energy values ​​on the first function is calculated. ,in, Indicates the first +1 energy value, Indicates the first One energy value, Indicates the first +1 energy value corresponds to the thickness difference of the detection point. Indicates the first The thickness difference at the detection point corresponding to each energy value It is a natural number greater than or equal to 1 and less than or equal to n; when the absolute value of the slope enters a stable stage as the energy value increases, the interval corresponding to the stable stage on the energy value is the stable interval, and the left endpoint of the stable interval is the optimal energy value.

[0013] Alternatively, when the absolute value of the slope is less than the target threshold for more than c consecutive times starting from the left endpoint, it is determined that the absolute value of the slope has entered a stable stage, where c is a natural number greater than or equal to 2.

[0014] To achieve the above and other related objectives, the present invention also provides a wafer measurement device for implementing the laser cleaning energy adjustment method described above. The wafer measurement device includes at least: a measurement module, a cleaning module, and an imaging device. The measurement module includes a first light source and a first detector. The first light source emits a first light signal from one side of the wafer. The first detector receives the first light signal reflected by the wafer and measures the thickness of the wafer. The cleaning module includes a second light source, an energy regulator, a dichroic mirror, and an objective lens. The second light source emits a second light signal. The energy regulator is positioned after the optical path of the second light source and adjusts the energy value of the second light signal. The dichroic mirror is positioned after the optical path of the energy regulator and vertically reflects the second light signal to the objective lens. The objective lens vertically transmits the second light signal reflected by the dichroic mirror to the wafer to clean the wafer. The imaging device is located directly above the dichroic mirror and observes the light spot formed on the wafer.

[0015] Optionally, the wafer measurement device further includes a third light source and a third detector; the third light source emits a third optical signal from one side of the wafer, and the third detector receives the third optical signal reflected by the wafer and obtains the reference coordinates of the wafer, the reference coordinates being used to calibrate the wafer coordinates obtained by the measurement module.

[0016] Optionally, the wafer measuring device further includes a position adjuster; the second light source is disposed on the position adjuster, and the position adjuster is used to adjust the position of the second light source relative to the wafer.

[0017] Optionally, the cleaning module further includes a beam splitter and a second detector; the beam splitter is disposed between the energy regulator and the dichroic mirror, and is used to transmit a portion of the second light signal to the dichroic mirror and reflect another portion of the second light signal to the second detector, the second detector being used to collect and monitor the energy of the second light signal.

[0018] As described above, the laser cleaning energy adjustment method and wafer measurement device of the present invention have the following beneficial effects:

[0019] 1. The present invention, by aligning the positions of the first light spot and the second light spot in advance, ensures that the measurement position of the first optical signal and the cleaning position of the second optical signal are the same position on the wafer, thereby avoiding erroneous correspondence between the measured thickness and the energy value of the second optical signal and improving the accuracy of the optimal energy value.

[0020] 2. By confirming the qualification of the second light spot, this invention can avoid the accidental impact of changes in the integrity, energy, and power of the second light spot on the cleaning of the second optical signal, thus ensuring a definite correspondence between the wafer cleaning effect and the energy value of the second optical signal.

[0021] 3. By reasonably setting the initial values ​​and increment values ​​of n energy values, this invention can improve the fitting of the first function; by reasonably setting the judgment criteria for the first function to enter the stable stage, the optimal energy value with the best cleaning effect and the smallest energy value can be accurately obtained. Attached Figure Description

[0022] Figure 1 The diagram shown is a flowchart illustrating the laser cleaning energy adjustment method of the present invention.

[0023] Figure 2 The diagram shows the first and second light spots of the present invention before their positions overlap.

[0024] Figure 3 The diagram shows the position of the first and second light spots of the present invention after they coincide.

[0025] Figure 4 The diagram shows a cut-off pattern of the second light spot of the present invention.

[0026] Figure 5 The diagram shows the distribution of the n probe points on the wafer according to the present invention.

[0027] Figure 6 This is a schematic diagram showing the fitting between the n energy values ​​and the n first thicknesses of the present invention.

[0028] Figure 7 This is a schematic diagram showing the fitting between the n energy values ​​and the n second thicknesses of the present invention.

[0029] Figure 8 The diagram shows a fitting relationship between the n energy values ​​and the n thickness differences of the present invention.

[0030] Figure 9 This diagram shows a comparison of the cleaning effects of the two wafer measurement devices of the present invention.

[0031] Figure 10 The diagram shown is a first structural schematic of the wafer measurement device of the present invention.

[0032] Figure 11 The diagram shown is a second structural schematic of the wafer measurement device of the present invention.

[0033] Component designation explanation

[0034] 1 Measurement Module

[0035] 1a First Light Source

[0036] 1b First Detector

[0037] 11 First light spot

[0038] 2 Cleaning Module

[0039] 2a Second Light Source

[0040] 2b energy regulator

[0041] 2c dichroic mirror

[0042] 2D objective lens

[0043] 2e beam splitter

[0044] 2f Second Detector

[0045] 21 Second light spot

[0046] 3 Imaging devices

[0047] The center of the field of view of the 31 imaging device

[0048] 4 support platforms

[0049] 5 wafers

[0050] 51 detection points

[0051] 6. Third Light Source

[0052] 7 Third Detector Detailed Implementation

[0053] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0054] Please see Figures 1-11It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0055] As the requirements for data monitoring of semiconductor products become increasingly stringent, multiple optical measurement devices are used to operate semiconductor production lines. Each optical measurement device integrates various optical modules. This means that the laser cleaning module not only needs to be aligned with the wafer but also with different optical modules. In addition, the optical signal of the laser cleaning module may have various spot-cutting problems in different optical measurement devices. Therefore, on the one hand, in actual operation, it is necessary to individually confirm the laser cleaning module of each optical measurement device, resulting in a waste of time and cost. On the other hand, the cleaning energy used by the laser cleaning module in each optical measurement device cannot ensure that impurities on the wafer surface are perfectly removed, so that the thickness measured after cleaning the wafer represents the true thickness of the wafer.

[0056] Therefore, in order to solve the above problems, this invention proposes a method for adjusting laser cleaning energy and a wafer measurement device, the specific technical solution of which is as follows:

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a method for adjusting the energy of laser cleaning, including the following steps:

[0059] like Figure 1 As shown, in step S1, a first optical signal is incident obliquely from one side of the reference wafer, and a second optical signal is incident perpendicularly from directly above the reference wafer.

[0060] Specifically, in this embodiment, the first optical signal is incident obliquely from one side of the wafer and reflected to the other side of the wafer. The thickness of the wafer can be measured by the first optical signal reflected by the wafer. The second optical signal is incident vertically from directly above the wafer. This is to facilitate the second optical signal to clean the wafer. The wafer can be a reference wafer or a wafer to be measured, which can be set according to the actual situation.

[0061] like Figure 1 As shown, in step S2, the first optical signal forms a first light spot at a reference point on the reference wafer, and the second optical signal forms a second light spot at a reference point on the reference wafer; the positions of the first light spot and the second light spot are aligned, and the second light spot is confirmed to be qualified.

[0062] Specifically, in this embodiment, the positions of the first light spot and the second light spot are overlapped to ensure that the measurement position of the first optical signal and the cleaning position of the second optical signal are the same position on the wafer. Further, as... Figure 2 and Figure 3 As shown, to overlap the two light spots, an imaging device 3 is provided directly above the reference wafer. The images of the first and second light spots are both moved to the target field of view of the imaging device 3. By visually aligning the first and second light spots, it can be accurately determined whether the centers of the light spots coincide. As an example, the target field of view of the imaging device 3 can be the center of the field of view of the imaging device 3. In practical applications, the target field of view used by the imaging device 3 can be set as needed, and is not limited to this embodiment. Furthermore, firstly, by adjusting the position of the reference wafer, the first light spot is moved to the target field of view of the imaging device 3. Then, by adjusting the position of the light source that generates the second light signal, the second light spot is moved to the target field of view of the imaging device 3.

[0063] Specifically, in this embodiment, before step S2, there is a step S2', which obtains the first coordinates of the reference point based on the first optical signal. When there is a deviation between the first coordinates and the reference coordinates of the reference point, the first coordinates need to be calibrated. As an example, when the first optical signal is provided by a single-wavelength ellipticity measurement light source, the first coordinates of the reference point will have a deviation. The reference coordinates of the reference point can be obtained through the ellipticity measurement module in the same wafer measurement device, and the first coordinates are calibrated based on the reference coordinates. In practical applications, the specific device and steps for calibrating the first coordinates can be set as needed, and are not limited to this embodiment.

[0064] Specifically, in this embodiment, the second optical signal is confirmed to be qualified because when the second optical signal is unqualified, the energy value of the second optical signal required for the same cleaning effect may fluctuate greatly, or the energy required for cleaning may not be generated. Confirming the second optical signal to be qualified helps to confirm the correspondence between the cleaning effect and the energy value of the second optical signal, and ensures that the second optical signal generates a cleaning effect. Further, the qualification evaluation parameters for the second optical spot are any one or a combination of two or more of the following: the integrity of the second optical spot, energy, and ablation size. For example, ... Figure 4As shown, when the second light spot exhibits beam cutting, it indicates that the shape of the second light spot is incomplete. By adjusting the position of the light source generating the second light signal, the beam cutting can be prevented. When the attenuation rate of the second light signal is greater than a preset attenuation rate, the energy of the second light spot is considered unqualified. The light source generating the second light signal is then replaced until the energy of the second light spot is qualified. When the size of the light spot generated by the ablation of the second light signal at the reference point is greater than a set value, the ablation size of the second light spot is considered unqualified. The position of the light source generating the second light signal is adjusted, or the light source generating the second light signal is replaced, until the ablation size of the second light spot is qualified. In practical applications, the qualification evaluation parameters of the second light spot can be set as needed, and are not limited to this embodiment.

[0065] like Figure 1 As shown, in step S3, the reference wafer is replaced with the wafer to be tested; n detection points are set on the wafer to be tested, and n incremental energy values ​​are set for the second optical signal, where n is a natural number greater than or equal to 2; the first thickness of the n detection points before cleaning is measured based on the first optical signal, the n detection points are cleaned one by one based on the n energy values ​​of the second optical signal, and the second thickness of the n detection points after cleaning is measured based on the first optical signal.

[0066] Specifically, in this embodiment, after the wafer under test replaces the reference wafer, the location measured by the first optical signal and the location cleaned by the second optical signal are the same position on the wafer under test. Further, as... Figure 5 As shown, to represent a typical cleaning scenario for the wafer under test, the n probe points on the wafer should be distributed as evenly as possible across the wafer, and the distribution area should cover the entire surface of the wafer to be cleaned as much as possible. Furthermore, as... Figure 6 As shown, the first thickness before cleaning is obtained based on the first optical signal at n detection points; the n energy values ​​of the second optical signal are used to clean the n detection points one-to-one (to improve the efficiency of obtaining the thickness difference); as... Figure 7 As shown, the second thickness after cleaning at n detection points is obtained based on the first optical signal. For example, as shown... Figure 6 , Figure 7 and Figure 8As shown, the light source of the second optical signal is a laser. The horizontal axis in the three figures represents the ratio of laser power, and the vertical axis represents the first thickness, the second thickness, and the thickness difference, respectively. To more closely fit the first function, the initial value of the n energy values ​​of the second optical signal is 'a', and the increment value of adjacent energy values ​​is 'b', where 'a' and 'b' are natural numbers greater than or equal to 1. In practical applications, the specific light source of the first optical signal and the specific values ​​of the n energy values ​​can be set as needed, and are not limited to this embodiment. Furthermore, the second thickness can be measured uniformly after cleaning all n detection points, which improves operational convenience; alternatively, laser cleaning and second thickness measurement can be performed continuously at one detection point before moving on to the next, until all n detection points are completed, which improves the measurement accuracy of the second thickness at each detection point. In practical applications, the specific operations for laser cleaning and thickness measurement can be set as needed, and are not limited to this embodiment.

[0067] like Figure 1 As shown, in step S4, the first thickness and the second thickness are subtracted one-to-one to establish a first function about n energy values ​​and n thickness differences, and the optimal energy value for wafer cleaning is obtained based on the first function.

[0068] Specifically, in this embodiment, the thicknesses of each first thickness and each second thickness are subtracted one-to-one to obtain the thickness difference of n detection points. Based on the energy values ​​corresponding to the n detection points, such as... Figure 8 As shown, a first function is established relating n energy values ​​and n thickness differences. Further, when the energy of the second optical signal increases to a certain value, impurities on the surface of the wafer under test will be completely removed, and the thickness difference obtained at the detection point will no longer change. That is, the slope of the first function will enter a stable phase, and the energy value corresponding to the leftmost side of the stable phase is the optimal energy value with the best cleaning effect and the lowest energy. Furthermore, the slope between adjacent energy values ​​on the first function is calculated. , Indicates the first +1 energy value, Indicates the first One energy value, Indicates the first +1 energy value corresponds to the thickness difference of the detection point. Indicates the first The thickness difference at the detection point corresponding to each energy value The slope is a natural number greater than or equal to 1 and less than or equal to n. When the absolute value of the slope enters a stable phase as the energy value increases, the interval corresponding to the stable phase in terms of energy value is the stable interval, and the left endpoint of the stable interval is the optimal energy value. For example, if the absolute value of the slope is less than the target threshold c times consecutively starting from the left endpoint of the stable interval, it is determined that the slope of the first function has entered a stable phase starting from the left endpoint of the stable interval, where c is a natural number greater than or equal to 2. Figure 8 As shown, the slope of the first function enters a stable phase starting from the energy value of a+22b, which is the optimal energy value. In practical applications, the required value of c and the target threshold for the stable phase can be set as needed, and are not limited to this embodiment.

[0069] It should be noted that this embodiment obtains an accurate correspondence between the wafer measurement thickness and the energy value of the second optical signal by aligning the first optical signal used for measurement and the second optical signal used for cleaning. Confirming the second optical spot's qualification provides a definite correspondence between the cleaning status and the energy value of the second optical signal. Setting a reasonable value for n and the distribution range of n detection points reflects the true and common conditions of wafer cleaning. By utilizing the functional characteristics of the first function and reasonably setting the judgment criteria for the stable stage, the optimal energy value during wafer cleaning can be accurately obtained, ensuring that impurities on the wafer surface are perfectly removed. Therefore, since this embodiment can obtain a definite and accurate correspondence between the cleaning effect and the cleaning energy value, and can obtain the optimal cleaning energy with high precision, therefore... Figure 9 As shown, with high consistency in mechanical performance and assembly performance, this embodiment can ensure that different wafer measurement devices achieve essentially the same wafer cleaning effect, that is, the first and second thickness measurement results of different devices are almost the same, which greatly reduces the production pressure on the customer's mass production line.

[0070] Example 2

[0071] like Figure 10 As shown, this embodiment provides a wafer measurement device, including: a measurement module 1, a cleaning module 2, and an imaging device 3.

[0072] like Figure 10 As shown, the measurement module 1 includes a first light source 1a and a first detector 1b; the first light source 1a emits a first light signal from one side of the wafer 5; the first detector 1b receives the first light signal reflected by the wafer 5 and measures the thickness of the wafer 5.

[0073] Specifically, in this embodiment, the wafer 5 is placed on a support stage 4, which can be used to move the wafer 5. A first light source 1a and a first detector 1b are respectively disposed on both sides of the wafer 5, and the first detector 1b can measure the thickness of the wafer 5. As an example, such as... Figure 10As shown, the first light source 1a and the first detector 1b can be selected from the light source and detector in the ellipsometric optical system. Further, as... Figure 11 As shown, the wafer measurement device also includes a third light source 6 and a third detector 7. The third light source 6 emits a third optical signal from one side of the wafer 5, and the third detector 7 receives the third optical signal reflected from the wafer 5 and obtains the reference coordinates of the wafer 5. The reference coordinates are used to calibrate the wafer coordinates obtained by the measurement module 1. As an example, the first light source 1a and the first detector 1b are respectively selected from the light source and detector in a single-wavelength ellipsometric measurement optical system, and the third light source 6 and the third detector 7 are respectively selected from the light source and detector in an ellipsometric measurement optical system. In practical applications, the required first light source 1a, first detector 1b, third light source 6, and third detector 7 can be set as needed, and are not limited to this embodiment.

[0074] like Figure 10 As shown, the cleaning module 2 includes a second light source 2a, an energy regulator 2b, a dichroic mirror 2c, and an objective lens 2d. The second light source 2a emits a second light signal. The energy regulator 2b is positioned after the optical path of the second light source 2a and adjusts the energy value of the second light signal. The dichroic mirror 2c is positioned after the optical path of the energy regulator 2b and vertically reflects the second light signal to the objective lens 2d. The objective lens 2d vertically transmits the second light signal reflected by the dichroic mirror 2c to the wafer 5 to clean the wafer 5.

[0075] Specifically, in this embodiment, the second light source 2a emits a second light signal, and the energy regulator 2b, dichroic mirror 2c, and objective lens 2d are sequentially arranged in the optical path of the second light signal to perpendicularly incident the second light signal onto the wafer 5. Further, the second light source 2a is located to the left or right of the dichroic mirror 2c to prevent it from affecting the observation of the imaging device. The energy regulator 2b is arranged in the optical path between the second light source 2a and the dichroic mirror 2c to ensure that the state of the second light signal is consistent before entering the dichroic mirror 2c. Even further, the objective lens 2d is located directly above the wafer 5, and the dichroic mirror 2c is located directly above the objective lens 2d to ensure that the second light signal is perpendicularly incident on the wafer 5, facilitating cleaning of the wafer 5.

[0076] Specifically, in this embodiment, the wafer measurement device further includes a position adjuster, and the second light source 2a is disposed on the position adjuster, which is used to adjust the position of the second light source 2a. Further, relative to the wafer 5, the positions of the second light source 2a, the energy regulator 2b, the dichroic mirror 2c, and the objective lens 2d should ensure that the second light signal is perpendicularly incident on the detection point on the wafer 5. After confirming the positions of the energy regulator 2b, the dichroic mirror 2c, and the objective lens 2d in sequence, adjusting the position of the second light source 2a using the position adjuster can make the second light spot coincide with the position of the first light spot, and ensure that the second light spot meets the qualification standard. As an example, the position adjuster can adopt a five-axis (X-axis / Y-axis / Z-axis / rotation axis around the X-axis / rotation axis around the Y-axis) adjustment bracket. In practical applications, the specific mechanical type of the position adjuster can be set as needed, and is not limited to this embodiment.

[0077] Specifically, in this embodiment, the cleaning module 2 further includes a beam splitter 2e and a second detector 2f. The beam splitter 2e is positioned between the energy regulator 2b and the dichroic mirror 2c, and is used to transmit a portion of the second light signal to the dichroic mirror 2c and reflect another portion of the second light signal to the second detector 2f. The second detector 2f is used to collect and monitor the energy of the second light signal to prevent errors in the energy value of the second light signal before it enters the dichroic mirror 2c. Furthermore, the beam splitter 2e is positioned in the optical path after the energy regulator 2b to ensure that the state of the second light signal is consistent before it enters the beam splitter 2e, preventing errors in steps such as aligning the second light signal with the first light signal and confirming the qualification of the second light signal.

[0078] like Figure 10 As shown, imaging device 3 is located directly above dichroic mirror 2c and observes the light spot formed on wafer 5.

[0079] Specifically, in this embodiment, the imaging device 3 is positioned directly above the dichroic mirror 2c. When the first light signal is transmitted to the detection point of the wafer 5, the first light spot formed on the detection point of the wafer 5 can be observed through diffuse reflection of the first light signal on the wafer 5. When the second light signal is incident perpendicularly to the detection point of the wafer 5, the second light spot formed on the detection point of the wafer 5 can be observed through perpendicular reflection of the second light signal on the wafer 5, transmission through the objective lens 2d, and transmission through the dichroic mirror 2c. Furthermore, by utilizing the target field of view of the imaging device 3, the positions of the first light spot and the second light spot can be aligned. As an example, the imaging device 3 can be a camera. In practical applications, the specific type of imaging device 3 can be selected as needed, and is not limited to this embodiment.

[0080] It should be noted that the wafer measurement device of this embodiment can be applied to the laser cleaning energy adjustment method of Embodiment 1, or to other laser cleaning energy adjustment methods.

[0081] In summary, the laser cleaning energy adjustment method of the present invention includes the following steps: First, a first optical signal and a second optical signal are provided to a reference wafer, the positions of the first light spot and the second light spot are aligned, and the second light spot is confirmed to be qualified; Second, the reference wafer is replaced with a wafer to be tested, n detection points are set on the wafer to be tested, n energy values ​​are set for the second optical signal, the first thickness of the n detection points before cleaning is measured based on the first optical signal, the n detection points are cleaned one-to-one based on the n energy values ​​of the second optical signal, and the second thickness of the n detection points after cleaning is measured based on the first optical signal; Finally, the first thickness and the second thickness are subtracted one-to-one to establish a first function about the n energy values ​​and the n thickness differences, and the optimal energy value with the best cleaning effect and the smallest energy value is obtained based on the first function. The wafer measurement device of the present invention is used to implement a method for adjusting laser cleaning energy, comprising: a measurement module, a cleaning module, and an imaging device; the measurement module is used to measure the thickness of the wafer and includes a first light source and a first detector; the cleaning module is used to clean the wafer and includes a second light source, an energy regulator, a dichroic mirror, and an objective lens; the imaging device is used to observe the light spot formed on the wafer and is positioned directly above the dichroic mirror. The present invention has the advantages of being safe and reliable, simple to operate, highly stable, highly reliable, highly accurate, and easy to assemble and adjust on-site at the client's location. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for adjusting the energy of laser cleaning, characterized in that, The method for adjusting the laser cleaning energy includes at least the following steps: S1: A first optical signal is incident at an angle from one side of the reference wafer, and a second optical signal is incident perpendicularly from directly above the reference wafer; S2: The first optical signal forms a first light spot at a reference point on the reference wafer, and the second optical signal forms a second light spot at the reference point; the positions of the first light spot and the second light spot are aligned, and the second light spot is confirmed to be qualified; S3: Replace the reference wafer with the wafer to be tested; set n detection points on the wafer to be tested, and set n incremental energy values ​​for the second optical signal, where n is a natural number greater than or equal to 2; measure the first thickness of the n detection points before cleaning based on the first optical signal, clean the n detection points one by one based on the n energy values ​​of the second optical signal, and then measure the second thickness of the n detection points after cleaning based on the first optical signal. S4: Subtract the first thickness and the second thickness one by one to establish a first function about n energy values ​​and n thickness differences, and obtain the optimal energy value for wafer cleaning based on the first function.

2. The method for adjusting laser cleaning energy according to claim 1, characterized in that: Before step S2, there is a step S2', in which the first coordinates of the reference point are obtained based on the first optical signal, and the first coordinates are calibrated when there is a deviation between the first coordinates and the reference coordinates.

3. The method for adjusting laser cleaning energy according to claim 1, characterized in that: In step S2, an imaging device is provided directly above the reference wafer to move the images of the first light spot and the second light spot to the target field of view of the imaging device so as to overlap the first light spot and the second light spot.

4. The method for adjusting laser cleaning energy according to claim 3, characterized in that: In step S2, the first light spot is first moved to the target field of view by adjusting the position of the reference wafer; then, the second light spot is moved to the target field of view by adjusting the position of the light source that generates the second light signal.

5. The method for adjusting laser cleaning energy according to claim 1, characterized in that: In step S2, the qualification evaluation parameters for the second light spot are any one or a combination of two or more of the following: the integrity of the second light spot, energy, and ablation size.

6. The method for adjusting laser cleaning energy according to any one of claims 1-5, characterized in that: In step S4, the slope between adjacent energy values ​​on the first function is calculated. ,in, Indicates the first +1 energy value, Indicates the first One energy value, Indicates the first +1 energy value corresponds to the thickness difference of the detection point. Indicates the first The thickness difference at each detection point corresponding to an energy value It is a natural number greater than or equal to 1 and less than or equal to n; when the absolute value of the slope enters a stable stage as the energy value increases, the interval corresponding to the stable stage on the energy value is the stable interval, and the left endpoint of the stable interval is the optimal energy value.

7. The method for adjusting laser cleaning energy according to claim 6, characterized in that: When the absolute value of the slope is less than the target threshold for more than c consecutive times starting from the left endpoint, the absolute value of the slope is determined to have entered a stable phase, where c is a natural number greater than or equal to 2.

8. A wafer measurement device for implementing the laser cleaning energy adjustment method according to any one of claims 1-7, characterized in that, The wafer measurement device includes at least: a measurement module, a cleaning module, and an imaging device; The measurement module includes a first light source and a first detector; the first light source emits a first light signal from one side of the wafer; the first detector receives the first light signal reflected by the wafer and measures the thickness of the wafer; The cleaning module includes a second light source, an energy regulator, a dichroic mirror, and an objective lens. The second light source emits a second light signal. The energy regulator is positioned after the optical path of the second light source and adjusts the energy value of the second light signal. The dichroic mirror is positioned after the optical path of the energy regulator and vertically reflects the second light signal to the objective lens. The objective lens vertically transmits the second light signal reflected by the dichroic mirror to the wafer to clean the wafer. The imaging device is located directly above the dichroic mirror and observes the light spot formed on the wafer.

9. The wafer measuring apparatus according to claim 8, characterized in that: The wafer measurement device further includes a third light source and a third detector; the third light source emits a third optical signal from one side of the wafer, and the third detector receives the third optical signal reflected by the wafer and obtains the reference coordinates of the wafer, which are used to calibrate the wafer coordinates obtained by the measurement module.

10. The wafer measuring apparatus according to claim 8, characterized in that: The wafer measurement device further includes a position adjuster; the second light source is disposed on the position adjuster, and the position adjuster is used to adjust the position of the second light source relative to the wafer.

11. The wafer measurement apparatus according to any one of claims 8-10, characterized in that: The cleaning module also includes a beam splitter and a second detector; the beam splitter is disposed between the energy regulator and the dichroic mirror, and is used to transmit a portion of the second light signal to the dichroic mirror and reflect another portion of the second light signal to the second detector, the second detector being used to collect and monitor the energy of the second light signal.

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