TWI539137B - Measuring device and measuring method - Google Patents

Description

Measuring device and measuring method

The present invention relates to an apparatus and method, and more particularly to a measuring apparatus and a measuring method.

In the semiconductor process, it is an important technology to make new crystals on the original wafer to make the epitaxial technology of the new semiconductor layer wafer. The main reason is that the wafer will form a concave or convex shape. In the epitaxial process, the epitaxial semiconductor layer and the original wafer film have different lattice constants or different thermal expansion coefficients, which cause the overall epitaxial structure to be deformed, and excessive deformation causes the epitaxial film to rupture. In the epitaxial technology, if the curvature change of the epitaxial structure can be measured instantaneously, the flow rate of the gas to be applied and the temperature applied can be determined according to the curvature change, thereby reducing the deformation of the overall epitaxial structure, and therefore, measuring the curvature of the epitaxial structure Change is more and more important.

However, on the market today, the machine used to measure the change of curvature has a high cost and thus cannot be widely used.

Accordingly, a first object of the present invention is to provide a measuring device which is low in cost and which can measure the change in curvature of an object to be measured.

Thus, the measuring device of the present invention comprises: An optical unit that emits a continuous laser beam to a surface of an object to be measured to form a path and generates a plurality of reflected lights; a position detector for receiving the reflected light and including an interval along a first direction a first electrode and a second electrode, wherein each of the reflected light forms a first current and a second current at the first electrode and the second electrode, respectively, and the first current and the second current respectively And the distance from the incident point of the reflected light to the position detector to the first electrode and the second electrode is inversely proportional; and an operation unit electrically connecting the position detector to receive each of the first and the first Two currents, and subtracting the first and second currents to generate a subtraction signal, and adding the first and second currents to generate an addition signal, the operation unit according to the subtraction signals and the The addition signal is operated to obtain a curvature of a path formed by the laser beam on the surface of the object to be tested, wherein the curvature is proportional to the subtraction signal and inversely proportional to the addition signal.

A second object of the present invention is to provide a measurement method which is low in cost and which can measure the curvature change of an object to be measured.

The measuring method of the present invention comprises: (A) using an optical unit to emit a continuous laser beam to a surface of an object to be measured to form a path and generating a plurality of reflected lights; (B) receiving the reflected light by using a position detector. Forming a first current and a second current in a first electrode and a second electrode respectively disposed along a first direction, and respectively, the magnitudes of the first current and the second current are respectively And the reflected light is incident on the position detector An incident point is inversely proportional to a distance between the first electrode and the second electrode; and (C) receiving, by an arithmetic unit, each of the first and second currents, and subtracting the first and second currents to generate a subtraction signal, and adding the first and second currents to generate an addition signal, and calculating, by the operation unit, the subtraction signal and the addition signal to obtain a surface of the object to be tested The curvature of the path formed by the laser beam, wherein the curvature is proportional to the subtraction signal and inversely proportional to the addition signal.

1‧‧‧ Optical unit

11‧‧‧Laser diode circuit

12‧‧‧Adjusting the drive circuit

121‧‧‧First amplifier

122‧‧‧Optoelectronics

21‧‧‧ platform

211‧‧‧Package

22‧‧‧Motor

3‧‧‧Location detector

31‧‧‧ substrate layer

32‧‧‧Essential layer

33‧‧‧resistance layer

34‧‧‧First electrode

35‧‧‧second electrode

36‧‧‧ incident point

4‧‧‧ arithmetic unit

41‧‧‧ converter

411‧‧‧second amplifier

412‧‧‧3rd amplifier

413‧‧‧output

414‧‧‧output

42‧‧‧Adder

421‧‧‧4th amplifier

43‧‧‧Subtractor

431‧‧‧5th amplifier

44‧‧‧ processor

5‧‧‧ display

6‧‧‧ objects to be tested

LD‧‧‧Laser diode

D‧‧‧ diode

R‧‧‧Variable resistor

R ₁ ‧‧‧first resistance

R ₂ ‧‧‧second resistance

R ₃ ‧‧‧third resistor

R ₄ ‧‧‧fourth resistor

R ₅ ‧‧‧ fifth resistor

R ₆ ‧‧‧6th resistor

R ₇ ‧‧‧ seventh resistor

R ₈ ‧‧‧8th resistor

R ₉ ‧‧‧ninth resistor

R ₁₀ ‧‧‧10th resistor

R ₁₁ ‧‧‧Eleventh resistor

R ₁₂ ‧‧‧12th resistor

C ₁ ‧‧‧first capacitor

C ₂ ‧‧‧second capacitor

I _X1 ‧‧‧First current

I _X2 ‧‧‧second current

V ₁ ‧‧‧First voltage

V ₂ ‧‧‧second voltage

V _neg ‧‧‧Negative power supply

Sum‧‧ Addition signal

Diff‧‧‧ subtraction signal

A01‧‧‧ Carrying steps

A02‧‧‧ move steps

A03‧‧‧Drive adjustment steps

A‧‧‧ launching steps

B‧‧‧Detection steps

C‧‧‧Operation steps

C1‧‧‧ conversion steps

C2‧‧‧Addition steps

C3‧‧‧ subtraction steps

C4‧‧‧Processing steps

C5‧‧‧ judgment steps

C6‧‧‧Deposition calculation steps

D‧‧‧Display steps

Other features and advantages of the present invention will be apparent from the embodiments of the present invention. FIG. 1 is a block diagram illustrating a preferred embodiment of the measuring device of the present invention; FIG. 2 is a circuit diagram. An optical unit of the preferred embodiment; FIG. 3 is a schematic diagram showing a platform of the preferred embodiment; FIG. 4 is a structural diagram illustrating a position detector of the preferred embodiment; FIG. A circuit diagram illustrating a converter of the preferred embodiment; FIG. 6 is a circuit diagram illustrating an adder and a subtractor of the preferred embodiment; FIG. 7 is a flow chart illustrating the execution of the preferred embodiment The steps of the method for measuring the invention; FIG. 8 is a measurement diagram illustrating an addition signal of the preferred embodiment; FIG. 9 is a measurement diagram illustrating a subtraction signal of the preferred embodiment; FIG. 10 is an amount Mapping to illustrate a divide signal of the preferred embodiment; Figure 11 is a schematic view showing the preferred embodiment for determining that the surface of an object to be tested is concave; Figure 12 is a schematic view showing that the preferred embodiment determines that the surface of the object to be tested is convex; and Figure 13 is A simulation diagram illustrating the addition signal used to determine the thickness of the preferred embodiment.

Referring to FIG. 1, a preferred embodiment of the measuring device of the present invention emits a continuous laser beam to an object 6 to be measured to generate a plurality of reflected lights, and the reflected light is processed to obtain a curvature value and a surface of the object 6 to be tested. Morphology. In this example, the measuring device can be combined with an epitaxial processing device to instantly measure the curvature change of the epitaxial structure and the thickness of the epitaxial layer in the epitaxial process, and the measuring device comprises a The optical unit 1, a platform 21, a motor 22, a Position Sensing Detector (PSD) 3, an arithmetic unit 4, and a display 5.

The optical unit 1 includes a laser diode circuit 11 and an adjustment driving circuit 12 electrically connected to the laser diode circuit 11. The adjustment driving circuit 12 can drive the laser diode circuit 11 to emit the same. The laser beam controls its power intensity and focus point.

Referring to FIG. 2, the laser diode circuit 11 has a laser diode LD and a diode D. The laser diode LD has a grounded anode and a cathode. The diode D is used to protect the laser diode LD from receiving a reverse current and is burned, and has an anode electrically connected to the cathode of the laser diode LD, and an anode electrically connected to the laser diode Cathode.

The adjustment driving circuit 12 has a first resistor R ₁ , a second resistor R ₂ , a variable resistor R, a first amplifier 121, a transistor 122, and a third resistor R ₃ . The first resistor R ₁ has a grounded first end and a second end. The second resistor R ₂ has a first end and a second end electrically connected to a negative power source V _neg . The variable resistor R having a resistance R is connected electrically to the first and second ends of the first _1, a second terminal and a third terminal electrically connected to the second resistor R ₂ to the first end. The first amplifier 121 has a non-inverting input terminal electrically connected to the second end of the variable resistor R, an inverting input terminal, and an output terminal. The transistor 122 is an NPN-type bipolar junction transistor having an emitter electrically connected to the inverting input end of the first amplifier 121, a base electrically connected to the output end of the first amplifier 121, and a base The collector of the cathode of the laser diode LD is electrically connected. The third resistor R ₃ has a first end electrically connected to the emitter of the transistor 122 and a second end electrically connected to the negative power source V _neg .

Referring to FIG. 3, in this example, the waiting object 6 is a deposited wafer, and the platform 21 includes six carriers 211 for holding the waiting object 6, respectively, and the motor 22 drives the platform 21 toward the clock. The directions are revolved, and the carriers 211 are rotated in the counterclockwise direction, respectively.

Referring to FIG. 4, the structure of the position detector 3 can be regarded as a PIN diode (P-intrinsic-N Diode), and includes a substrate layer 31 made of an N-type high resistance 矽 substrate, and a substrate layer. An intrinsic layer 32 of a high-resistance semiconductor, a resistive layer 33 on the intrinsic layer 32 and a material of a P-type semiconductor, and two on the resistive layer 33 and spaced apart along a first direction X and The first electrode 34 and the second electrode 35 are respectively adjacent to opposite sides of the resistive layer 33, and the first and second electrodes 34 and 35 are made of metal. The position detector 3 is configured to receive the reflected light, and each of the reflected light is incident on the resistive layer 33 and forms an electron hole pair at an incident point 36, respectively, by the first electrode 34 and the second electrode. 35 collects and separately forms a first current I _X1 and a second current I _X2 . It should be noted that the position of the incident point 36 is between the first and second electrodes 34, 35. The magnitudes of the first and second currents I _X1 and I _X2 are inversely proportional to the distance from the incident point 36 to the first and second electrodes 34 and 35, respectively. Therefore, based on the magnitudes of the first and second currents I _X1 and I _X2 , the position of the incident point 36 at the resistive layer 33 can be determined. In addition, the number of pairs of electron holes formed at the position of the incident point 36 is proportional to the amount of reflected light incident on the resistive layer 33, and the size of the reflected light can be controlled by the laser light.

Referring to FIGS. 1 and 5, the arithmetic unit 4 includes a converter 41, an adder 42, a subtractor 43, and a processor 44. The converter 41 has a second amplifier 411, a third amplifier 412, a fourth resistor R ₄ , and a fifth resistor R ₅ . The second amplifier 411 has a grounded non-inverting input terminal, an inverting input terminal electrically connected to the second electrode 35 and receiving the second current I _X2 , and an output terminal 413 . The third amplifier 412 has a grounded non-inverting input, an inverting input electrically connected to the first electrode 34 and receiving the first current I _X1 , and an output 414 . The fourth resistor R ₄ has a first end electrically connected to the inverting input terminal of the second amplifier 411, and a second end electrically connected to the output end 413 of the second amplifier 411. The fifth resistor R ₅ has an electrical output of the third amplifier 412 to the first end, and electrically connected to a third inverting input terminal of the amplifier 412 is connected to the second ends 414.

Referring to FIGS. 5 and 6, the adder 42 has a fourth amplifier 421, a sixth resistor R _6, a seventh resistor R _7, an eighth resistor R _8, and a first capacitor C _1. The fourth amplifier 421 has a grounded non-inverting input terminal, an inverting input terminal, and an output terminal for outputting an addition signal Sum. The sixth resistor R ₆ has a first end electrically connected to the output end 413 of the second amplifier 411, and a second end electrically connected to the inverting input end of the fourth amplifier 421. The seventh resistor R ₇ having an electrical output of the third amplifier 412 is connected to the end of the first end 414 and a second end electrically connected to the inverting input of the fourth amplifier 421. The eighth resistor R ₈ has a first end electrically connected to the inverting input end of the fourth amplifier 421, and a second end electrically connected to the output end of the fourth amplifier 421. The first capacitor C ₁ having a first end electrically connected to a first terminal of the eighth resistor R _8, and an eighth resistor R electrically connected to the second end of the second end _8.

The subtractor 43 has a fifth amplifier 431, a ninth resistor R _9, a tenth resistor R _10, a eleventh resistor R _11, a twelfth resistor R _12, and a second capacitor C _2. The fifth amplifier 431 has a non-inverting input terminal, an inverting input terminal, and an output terminal for outputting a subtraction signal Diff. The ninth resistor R ₉ has a grounded first end and a second end electrically connected to the non-inverting input of the fifth amplifier 431. The tenth resistor R ₁₀ has a second amplifier electrically connected to the output terminal 411 of the first end, and an electrical connector 413 of the ninth second ends of the resistor R _9. The eleventh resistor R ₁₁ having an electrical output of the third amplifier 412 is connected to the end of the first end 414 and a second end electrically connected to the inverting input terminal of the fifth amplifier 431. The twelfth resistor R ₁₂ has a first end electrically connected to the second end of the eleventh resistor R _11, and a second terminal electrically connected to the fifth output terminal of the amplifier 431. The second capacitor C ₂ having a first end electrically connected to a first end of the twelfth resistor R _12, and a second end electrically connected to the second end ₁₂ of the twelfth resistor R.

Referring to FIG. 1, FIG. 3 and FIG. 7, the measuring device performs a measuring method for measuring the curvature value, the change trend and the thickness of the surface topography of the waiting object 6, and the measuring method comprises the following steps:

Step A01: The platform 21 is used to carry the waiting object 6 , and the waiting object 6 to be measured is placed on the platform 21 . In this example, the wafers to be measured are placed on the carrier 211 of the platform 21, respectively.

Step A02: The motor 22 is used to drive the platform 21 to move, so that the waiting object 6 is driven by the motor 22 to move on the platform 21, and the laser diode circuit 11 emits a continuous laser beam to the waiting. The object 6 can produce a plurality of reflected light of the entire surface. In this example, the motor 22 drives the platform 21 to revolve and the carriers 211 rotate, respectively, to obtain the reflected light of the wafers during deposition.

Step A03: The laser diode circuit 11 is driven by the adjustment driving circuit 12 to emit the laser beam, and the power intensity and the focus point of the laser beam are adjusted. In this example, the variable resistor R is adjusted to control the current flowing through the laser diode LD. As shown in FIG. 2, the power intensity and focus of the laser beam emitted by the laser diode LD can be controlled. Far and near.

Step A: using the laser diode circuit 11 of the optical unit 1 to emit a continuous laser beam to form a surface of the waiting object 6 A path produces a complex reflected light.

Step B: receiving the reflected light by the position detector 3, so that each reflected light forms the first current I _X1 related to the position information of the incident point 36 at the first electrode 34 and the second electrode 35, respectively. The second current I _{X2 is} as shown in FIG. 4 .

The detailed operation of step B is: the position detector 3 is disposed adjacent to the laser diode circuit 11, and when the surface of the object 6 to be measured is equivalent, the generated reflected light is incident on the position detection. The incident point 36 of the device 3 is located at a midpoint between the first and second electrodes 34, 35, and the first and second currents I _X1 , I respectively collected at the first and second electrodes 34, 35 _{X2 is the} same; if the surface of the object 6 to be measured is concave or convex, the incident point 36 is closer to one of the electrodes, and the current collected by the electrode adjacent to the incident point 36 is larger. For example, the incident point 36 is closer to the second electrode 35, and the first and second currents I _X1 and I _X2 respectively sensed by the first and second electrodes 34 and 35 are as follows: I _X1 = (L _X / 2-X _A )*I ₀ /L _X ............(1)

I _X2 = (L _X /2+X _A )*I ₀ /L _X ...........(2)

Wherein, the parameter Lx is the distance between the first and second electrodes 34, 35, and the parameter X _A is the distance between the midpoint between the first and second electrodes 34, 35 and the incident point 36, and I ₀ is When the incident point 36 is located at a midpoint between the first and second electrodes 34, 35, the first and second electrodes 34, 35 respectively collect the same current.

The result of subtracting the formula (2) from the formula (1) is obtained by adding the formula (2) and the formula (1): (I _X2 -I _X1 ) / (I _X1 +I _X2 )=2X _A /L _X ...........(3)

The value of the parameter X _A can be obtained from the formula (3), so that information on the position of the incident point 36 can be obtained.

Step C: receiving, by the operation unit 4, each of the first and second currents I _X1 and I _X2 , and subtracting the first and second currents I _X1 and I _X2 to generate the subtraction signal Diff, and The first and second currents I _X1 and I _X2 are added to generate the addition signal Sum, and the operation unit 4 performs an operation according to the subtraction signal Diff and the addition signal Sum to obtain the measured measurement. The surface of the object 6 is curvature of the path formed by the laser beam, wherein the curvature is proportional to the subtraction signal Diff and inversely proportional to the addition signal Sum, and the step C further comprises the following substeps:

Sub-step C1: The first and second currents I _X1 and I _{X2 are} received by the converter 41 and current-to-voltage conversion is performed to generate a first voltage V ₁ and a second voltage V _{2 , respectively} . In this example, the second current I _X2 is received from the inverting input of the second amplifier 411, and the second voltage V ₂ is output from the output 413 of the second amplifier 411 from the inverse of the third amplifier 412. The first current I _X1 is received from the input terminal, and the first voltage V ₁ is output from the output terminal 414 of the third amplifier 412, as shown in FIG.

Sub-step C2: The first and second voltages V ₁ and V _{2 are} received by the adder 42 and signal addition is performed to output the addition signal Sum. In this example, the first and second voltages V ₁ and V ₂ are input to the inverting input terminals of the fourth amplifier 421 through the sixth and seventh resistors R ₆ and R ₇ , respectively, from the fourth amplifier 421 . The output terminal outputs the addition signal Sum as shown in FIG. 6, and the change of the addition signal Sum with time is as shown in FIG.

Sub-step C3: receiving the first and second voltages V ₁ and V ₂ by the subtractor 43 and performing signal subtraction to output the subtraction signal Diff. In this example, the first and second voltages V ₁ and V ₂ are input to the inverting and non-inverting input terminals of the fifth amplifier 431 through the eleventh and tenth resistors R ₁₁ and R ₁₀ , respectively. The output of the fifth amplifier 431 outputs the subtraction signal Diff, as shown in FIG. 6, and the variation of the subtraction signal Diff with time is as shown in FIG.

Sub-step C4: The processor 44 receives the addition signal Sum and the subtraction signal Diff, and substitutes the subtraction signal Diff and its corresponding addition signal Sum into a curvature formula to obtain the measured object 6 to be measured. The curvature of the surface, the curvature formula is as follows: C=W(Diff/Sum)/HD...........(4)

The parameter C is the measured curvature of the object 6 to be measured, and the parameter W is one-half of the side length of the position detector 3 parallel to the first direction X, and the parameter H is the position detector 3 to The height of the object 6 to be measured is measured, and the parameter D is the length of the path formed by the laser beam on the surface of the object 6 to be measured.

In this example, the processor 44 divides each subtraction signal Diff by its corresponding addition signal Sum to obtain a division signal. The division signal changes with time as shown in FIG. The maximum value in 10 is subtracted from the minimum value and divided by two, and an intermediate value of the division signals is taken into the equation (4) to obtain the measured curvature of the surface of the object 6 to be measured.

Sub-step C5: using the processor 44 to determine, according to the change of the subtraction signal Diff over time, the surface of the object 6 to be measured is measured by The shape of the path formed by the laser beam.

Detailed operation of sub-step C5: Referring to FIG. 11, when the surface of the object 6 to be measured is concave, the change of the incident light 36 incident on the position detector 3 will be adjacent to the first a second electrode 35, to a midpoint of the first and second electrodes 34, 35, and then adjacent to the first electrode 34. In this example, the subtraction signal Diff is set to be the first current I _X1 minus the second current I _X2 Then, the trend of the subtraction signal Diff is first from a negative value to a positive value.

Referring to FIG. 12, when the surface of the object 6 to be measured is convex, the change of the incident light incident on the position detector 3 will be adjacent to the first electrode 34 to the first The midpoint of the first and second electrodes 34, 35 is adjacent to the second electrode 35. In this example, the subtraction signal Diff is set to the first current I _X1 minus the second current I _X2 , and the subtraction signal Diff is The trend is first to decrement from positive to zero.

If the measured surface of the object 6 to be measured is horizontal, the position of the reflected light incident point 36 will always be at the midpoint of the first and second electrodes 34, 35, and the subtraction signal Diff is always zero. Therefore, the change from the subtraction signal Diff can be used to determine the topography of the path formed by the laser beam on the surface of the object 6 to be measured. It is noted that the trend of the subtraction signal Diff will vary with the computing unit 4 is set by the second current I _X2 subtracting the first current of the first current I _X1 I _X1 or subtracting the second current I _X2 The change is also related to the direction in which the platform 21 is loaded by the object 6 to be measured. Further, the division signal is proportional to the subtraction signal Diff, and the surface topography of the object 6 to be measured can also be judged from the tendency of the division signal to change with time.

Sub-step C6: Referring to FIG. 1, the processor 44 can be used to know the thickness of the wafers during epitaxial fabrication to determine whether the wafers are uniform during deposition, and the processor 44 uses the subtraction signals. When the value is zero, the corresponding addition signal Sum is sampled to obtain a plurality of additive sampling points, and the additive sampling points are converted into a plurality of sine waves which change with time, and the thickness of the wafer which starts to be deposited to the end is:

Wherein, the parameter d is the measured thickness of the wafer, the parameter λ is the wavelength of the laser beam, the parameter n is the refractive index of the material of the wafer forming the measurement, and m is the number of sine waves varying with time.

Sub-step C6 is detailed: when the wafers are deposited, the variation of the plurality of additive sampling points over time will exhibit 4.5 chords in this example. As shown in FIG. 13, the processor 44 will chord. The number of waves and the wavelength of the laser beam are substituted into equation (5) to obtain the thickness of the wafers when they are deposited.

Step D: receiving and displaying information obtained from the operation unit 4 by using the display 5, for example, displaying the curvature of the surface of the object to be measured 6, and the processor 44 respectively determining the waiting object from the subtraction signal Diff or the division signal 6 The shape of the surface, and the thickness of the deposited object 6 to be deposited.

In addition, the adder 42, the subtractor 43, the processor 44, and the computer program that can be implemented by the display 5 in a software manner can be input to a hardware device (such as a processor) having computer processing capability. The adder 42, the subtractor 43, the processor 44, and the actions to be performed by the display 5 are executed.

In summary, the preferred embodiment uses the position detector 3 and the computing unit 4 to perform a measurement method, and the curvature value and trend of the surface topography can be obtained from the reflected light of the object 6 to be measured. The object to be tested 6 is a deposited wafer, and a measurement method is performed during the deposition process, and the deposition thickness of the object to be tested 6 can be known, and the cost can be reduced and the data can be widely used, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

1‧‧‧ Optical unit

11‧‧‧Laser diode circuit

12‧‧‧Adjusting the drive circuit

21‧‧‧ platform

22‧‧‧Motor

3‧‧‧Location detector

4‧‧‧ arithmetic unit

41‧‧‧ converter

42‧‧‧Adder

43‧‧‧Subtractor

44‧‧‧ processor

5‧‧‧ display

6‧‧‧ objects to be tested

Claims (16)

A measuring device comprising: an optical unit that emits a continuous laser beam to a surface of an object to be measured to form a path and generates a plurality of reflected lights; and a position detector for receiving the reflected light and including along a first electrode and a second electrode are disposed in a first direction, so that each of the reflected light respectively forms a first current and a second current at the first electrode and the second electrode, and the first current and The magnitude of the second current is inversely proportional to the distance from the incident point of the reflected light to the first electrode and the second electrode; and an arithmetic unit electrically connected to the position detector Receiving each of the first and second currents, and subtracting the first and second currents to generate a subtraction signal, and adding the first and second currents to generate an addition signal, the operation unit is configured according to The subtraction signals are operated with the addition signals to obtain a curvature of a path formed by the laser beam on the surface of the object to be tested, wherein the curvature is proportional to the subtraction signal and inversely proportional to the addition signal. The measuring device of claim 1, wherein the computing unit comprises: a converter, receiving the first and second currents and performing current to voltage conversion to respectively generate a first voltage and a second voltage; An adder receiving the first and second voltages and performing signal addition to output the addition signal; a subtractor receiving the first and second voltages and performing signal subtraction to output the subtraction signal; and a processor receives the addition signals and the subtraction signals, and substitutes the subtraction signals and their corresponding addition signals into a curvature formula to obtain a curvature of a surface of the object to be tested. The curvature formula is as follows: C =W(Diff/Sum)/HD, where the parameter C is the curvature of the object to be tested, and the parameter W is one-half of the side length of the position detector parallel to the first direction, and the parameter Diff is the subtraction signal. The parameter Sum is the addition signal, the parameter H is the height of the position detector to the object to be tested, and the parameter D is the length of the path formed by the laser beam on the surface of the object to be tested. The measuring device according to claim 1, further comprising: a platform carrying the object to be tested; and a motor driving the platform to move, so that the object to be tested is on the platform, and the optical unit generates the to-be-tested The reflected light from the entire surface of the object. The measuring device of claim 3, wherein the platform comprises a plurality of carriers for holding the object to be measured, the motor driving the platform to revolve and the carriers respectively rotating. The measuring device of claim 2, wherein the processor divides each subtraction signal by a corresponding addition signal to obtain a division signal, and then substitutes the division signal for an intermediate value into the curvature formula to obtain The curvature of the object to be tested. The measuring device of claim 2, wherein the processor determines that the surface of the object to be tested is determined by the change of the subtraction signal over time The shape of the path formed by the laser beam. The measuring device of claim 6, wherein when the surface of the object to be tested is concave, the position of the incident point changes to: first approach one of the first and second electrodes, to the first And the midpoint of the two electrodes, and then closer to the other of the first and second electrodes, the change of the subtraction signal with time is from a negative value to a positive value or a positive value to a negative value, and the movement related to the incident point Direction; when the surface of the object to be tested is horizontal, the position of the incident point will always be at the midpoint of the first and second electrodes, then the subtraction signal maintains zero with time; when the surface of the object to be tested In the convex shape, the change of the subtraction signal with time is opposite to when the surface of the object to be tested is concave. The measuring device of claim 2, wherein the object to be tested is a thin film deposited wafer, and the processor samples the addition signal corresponding to the subtraction signal value to zero to obtain a plurality of additive sampling points. And converting the additive sampling points into a plurality of time-varying sine waves, the thickness of the wafer starting to be deposited to the end is: Wherein, the parameter d is the thickness of the wafer, the parameter λ is the wavelength of the laser beam, the parameter n is the refractive index of the material forming the wafer, and m is the number of sine waves varying with time. A measuring method comprising: (A) using an optical unit to emit a continuous laser beam to a surface of an object to be measured to form a path and generating a plurality of reflected lights; (B) receiving the reflected light by using a position detector. To make each reflection The light respectively forms a first current and a second current in a first electrode and a second electrode spaced apart along a first direction, and the magnitudes of the first current and the second current are respectively incident on the reflected light And (C) receiving each of the first and second currents by using an arithmetic unit, and the first and second The two currents are subtracted to generate a subtraction signal, and the first and second currents are added to generate an addition signal, and the operation unit performs an operation on the subtraction signal according to the subtraction signals to obtain the The surface of the object to be tested is curvature of the path formed by the laser beam, wherein the curvature is proportional to the subtraction signal and inversely proportional to the addition signal. The measuring method of claim 9, wherein the step (C) comprises: (C1) receiving, by the operating unit, the first and second currents and performing current-to-voltage conversion to generate a first voltage, and a second voltage; (C2) receiving, by the arithmetic unit, the first and second voltages and performing signal addition to output the addition signal; (C3) receiving, by the operation unit, the first and second voltages and performing signal phase Subtracting and outputting the subtraction signal; and (C4) receiving, by the operation unit, the addition signal and the subtraction signal, and substituting the subtraction signal and its corresponding addition signal into a curvature formula to obtain a surface of the object to be tested The curvature, the curvature formula is as follows: C=W(Diff/Sum)/HD, where the parameter C is the curvature of the object to be tested, and the parameter W is one-half of the side length of the position detector parallel to the first direction, and the parameter Diff is the subtraction signal. The parameter Sum is the addition signal, the parameter H is the height of the position detector to the object to be tested, and the parameter D is the length of the path formed by the laser beam on the surface of the object to be tested. The measuring method according to claim 9, wherein the step (A) further comprises: (A01) using a platform to carry the object to be tested; and (A02) driving the platform to move by using a motor to make the waiting The measuring object on the platform allows the optical unit to generate reflected light of the entire surface of the object to be tested. The measuring method of claim 11, wherein in the step (A02), the platform comprises a plurality of carriers for holding the object to be measured, the motor driving the platform to revolve and the carriers respectively rotation. The measuring method according to claim 10, wherein in the step (C4), the arithmetic unit divides each subtraction signal by a corresponding addition signal to obtain a division signal, and then takes the division signal into a middle The value is substituted into the curvature formula to obtain the curvature of the object to be tested. The measuring method of claim 10, wherein the step (C) further comprises: (C5) determining, by the operating unit, the surface of the object to be tested from the laser beam according to the change of the subtraction signal over time The shape of the path formed. The measuring method according to claim 14, wherein in the step (C5), When the surface of the object to be tested is concave, the position of the incident point changes: first one of the first and second electrodes, to the midpoint of the first and second electrodes, and then to the other 1. The second electrode, the change of the subtraction signal with time is from a negative value to a positive value or a positive value to a negative value, which is related to the moving direction of the incident point; when the surface of the object to be tested is horizontal, The position of the incident point will always be at the midpoint of the first and second electrodes, and the subtraction signal maintains zero with time; when the surface of the object to be tested is convex, the subtraction signal changes with time is opposite to When the surface of the object to be tested is concave. The measuring method of claim 10, wherein the step (C) further comprises: (C6) when the object to be tested is a thin film deposited wafer, and the arithmetic unit uses the subtraction signal value to be zero. The corresponding addition signal is sampled to obtain a plurality of additive sampling points, and the additive sampling points are converted into a plurality of time-varying sine waves, and the thickness of the wafer starting to be deposited to the end is: Wherein, the parameter d is the thickness of the wafer, the parameter λ is the wavelength of the laser beam, the parameter n is the refractive index of the material forming the wafer, and m is the number of sine waves varying with time.