TWI861440B - Method of measuring depth of damage layer and concentration of defects in damage layer and system for performing the method - Google Patents

Abstract

The present invention provides a method for determining the depth of a damage layer formed on the back side of a substrate, which method may include: a step of irradiating a first light and a second light to the damage layer; a step of detecting the first light and the second light reflected or scattered by defects in the damage layer; a step of determining a first penetration depth of the first light and a second penetration depth of the second light based on a first wavelength of the first light and a second wavelength of the second light; and a step of determining the depth of the damage layer using the detected first penetration depth and the second penetration depth.

Description

Method for determining the depth of a damaged layer and the concentration of defects in the damaged layer and system for implementing the method

This application relates to a method for determining the depth of a damaged layer and the defect concentration within the damaged layer and a system for implementing the method.

According to the trend of miniaturization and lightweighting of semiconductor packages, the thickness of the wafer is reduced by grinding the back side of the wafer.

However, as the wafer thickness decreases, foreign matter such as metal ions like copper (Cu) will penetrate into the back of the wafer. To prevent the penetration of foreign matter, a damage layer is formed on the back of the wafer.

However, currently, TEM (Transmission Electron Microscopy) is used to determine whether the damaged layer has been formed to an appropriate depth (thickness). However, TEM is a destructive inspection method and requires a separate specimen for measurement.

The technical problem to be solved by this application is to provide a method for determining the depth of a damaged layer by using the defect concentration according to the wavelength of light irradiating the damaged layer.

However, the technical problems to be solved by this application are not limited to those mentioned above. A person skilled in the art can clearly understand other technical problems to be solved that are not mentioned through the following description.

According to an embodiment of the present application, a method for determining the depth of a damaged layer formed on the back side of a substrate may include the steps of irradiating the damaged layer with a first light and a second light; detecting the first light and the second light reflected or scattered by defects in the damaged layer; determining a first penetration depth of the first light and a second penetration depth of the second light based on a first wavelength of the first light and a second wavelength of the second light; and determining the depth of the damaged layer using the detected first penetration depth and the second penetration depth.

When the first wavelength is longer than the second wavelength, the first penetration depth may be deeper than the second penetration depth.

In the step of determining the depth of the damage layer, when the first information shown by the detected first light is the same as the second information shown by the detected second light, the second penetration depth can be determined as the depth of the damage layer.

In the step of determining the damage layer depth, when the number or concentration of defects related to the first penetration depth is the same as the number or concentration of defects related to the second penetration depth, the second penetration depth may be determined as the damage layer depth.

The method may also include the step of determining the number or concentration of defects existing in a first region corresponding to the first penetration depth using the detected first light; the step of determining the number or concentration of defects existing in a second region corresponding to the second penetration depth using the detected second light; and the step of determining the number or concentration of defects existing in a third region in the first region that is not included in the second region using the number or concentration of defects existing in the first region and the number and concentration of defects existing in the second region.

The method may also include the step of determining the defect concentration in the first region using the number or concentration of defects present in the first region; the step of determining the defect concentration in the second region using the number or concentration of defects present in the second region; and the step of determining the defect concentration in the third region using the number or concentration of defects present in the third region.

The step of irradiating the first light and the second light is to irradiate the damaged layer with the first light and the second light simultaneously, and the first light and the second light may be light dispersed from white light.

The step of irradiating the first light and the second light may be performed by irradiating the first light and the second light in sequence.

The substrate may be a silicon substrate.

According to another embodiment of the present application, a measuring system for determining the depth of a damaged layer formed on the back side of a substrate may include a light irradiator for irradiating the damaged layer with a first light and a second light having a wavelength different from the first light; a light detector for detecting the first light and the second light reflected or scattered by defects in the damaged layer; and a determining device for receiving information about the first light and information about the second light from the light detector, the determining device determining a first penetration depth and a second penetration depth of the first light based on a first wavelength of the first light and a second wavelength of the second light, and using the first penetration depth and the second penetration depth, the depth of the damaged layer can be determined.

Beneficial effects of the present invention: According to the embodiments of the present application, the depth of the damaged layer is determined by utilizing the defect concentration following the wavelength of light irradiated to the damaged layer, and the depth of the damaged layer is obtained in a non-destructive manner.

10: Measurement system

10’: Measurement system

110: Substrate

111: Above

112: Back

120: Damage layer

121: Defects

200: Light irradiator

200’: Light irradiator

300: Light detector

400: Decision device

410: Defect quantity determination department

420: Determination of penetration depth

430: Defect concentration determination unit

440: Damage layer depth determination unit

t:Damage layer depth

B: Light

A1: Area 1

A2: Second area

A3: The third area

B_B: Blue light

B_G: Green light

B_R: Red light

PD_B: Penetration depth of blue light

PD_G: Penetration depth of green light

PD_R: Penetration depth of red light

S410: Defect quantity determination department

S420: Penetration depth determination unit

S430: Defect concentration determination unit

S440: Damage layer depth determination unit

S700: Expose light to the damaged layer

S710: Detects light reflected from defects contained in the damaged layer

S720: Determine the number of defects based on the wavelength of light

S730: Determine the penetration depth based on the wavelength of light

S740: Determine the defect concentration within the damaged layer

S750: Determine the depth of the damaged layer

FIG1 shows a measuring system for measuring the depth of a damaged layer and the defect concentration in the damaged layer according to an embodiment of the present application; FIG2 shows a conceptual structural diagram of the function of a determination device for determining the depth of a damaged layer and the defect concentration in the damaged layer according to an embodiment of the present application; FIG3 shows an example of determining the depth of a damaged layer and the defect concentration in the damaged layer; FIG4 shows a method for determining the depth of a damaged layer according to an embodiment of the present application; FIG5 shows a method for measuring the depth of a damaged layer and the defect concentration in the damaged layer when a light irradiator irradiates a plurality of lights having different wavelengths according to an embodiment of the present application.

FIG6 shows a method for measuring the depth of a damaged layer and the defect concentration in the damaged layer when a light irradiator irradiates a light having different wavelengths according to an embodiment of the present application.

FIG7 shows a flow chart of a method for determining the depth of a damaged layer and the defect concentration within the damaged layer according to an embodiment of the present application.

The advantages and features of the present application and its implementation methods will become clear with reference to the attached figures and the embodiments described in detail below. However, the present application is not limited to the embodiments disclosed below, but can be implemented in a variety of different forms. The embodiments are only provided to make the disclosure of the present application complete and to fully inform ordinary technicians in the technical field to which the present application belongs of the invention scope. The present application is only defined according to the scope of the claim.

Briefly explain the terms used in this manual and describe this application in detail.

The terms used in this application are selected as general terms that are currently widely used as much as possible in consideration of the function of this application, but they may change according to the intention of the general knowledge of the field or precedents, the emergence of new technologies, etc. Moreover, in certain cases, there are terms that the applicant arbitrarily selects, in which case, their meanings will be explained in detail in the specification of the corresponding invention. Therefore, the terms used in this application are not simply the names of the terms, but are defined according to the meanings of the terms and the contents throughout this application.

When a part of the entire specification "includes" a certain constituent element, unless otherwise stated to the contrary, this means that other constituent elements may be further included, rather than excluding other constituent elements.

In the following, in order to facilitate easy implementation by those of ordinary knowledge in the technical field to which this application belongs, the embodiments of this application will be described in detail with reference to the attached drawings. When describing the embodiments of this application with reference to the attached drawings, if it is judged that the detailed description of common knowledge or structure may unnecessarily confuse the gist of this application, its detailed description will be omitted. In addition, the terms described below are defined in consideration of the functions in the embodiments of this application, and may vary according to the intention or custom of the user or operator. Therefore, their definitions should be defined in accordance with the contents throughout this specification.

FIG1 shows a measurement system for measuring the depth of a damaged layer and the defect concentration within the damaged layer according to an embodiment of the present application.

Referring to FIG. 1 , the measuring system 10 may include a substrate 110, a damage layer 120, a light irradiator 200, and a light detector 300.

The substrate 110 may be a component prepared to enable packaging of various types of configurations.

According to an embodiment, the substrate 110 may be a silicon substrate. Infrared light can completely penetrate the silicon substrate. The shorter the wavelength of the silicon substrate, the higher the light absorption rate, and has the characteristic of reduced penetration depth. Therefore, light near visible light is partially absorbed in the thin film of the silicon substrate (approximately the depth of the damage layer or the thickness of Si of the wafer), and part can penetrate to a certain depth.

The substrate 110 may include an upper surface 111 on which electronic devices (not shown in the figure) may be packaged/attached and a back surface 112 opposite to the upper surface 111.

The damage layer 120 is to prevent/mitigate external foreign matter (especially metal ions such as copper)

Penetrating into the structure of the substrate 110, the damage layer 120 can be formed inside the substrate 110 from the back side 112 thereof by grinding.

According to the embodiment, the depth (t) of the damage layer 120 can be greater than 1 micron and less than 30 microns.

The light irradiator 200 can irradiate light B to the back side of the damaged layer 120 in order to measure the depth of the damaged layer 120 and the distribution degree of each depth of the defects 121 in the damaged layer 120 (i.e., the concentration of each depth). In this specification, the defects 121 can include point defects, line defects and surface defects.

The light B irradiated by the light irradiator 200 includes white light, LED, blue laser, green laser, red laser, etc., but is not limited thereto. That is, the light B irradiated by the light irradiator 200 can be a type of light suitable for measuring the depth of the damaged layer 120 and the defect concentration in the damaged layer.

In addition, in this specification, for the convenience of explanation, only visible light such as red light, green light, and blue light are described, but it is not limited to this. That is, the light B in this specification is not only visible light, but also includes light with near-infrared and near-ultraviolet wavelengths.

If the light B irradiated from the light irradiator 200 is reflected on the surface of the damaged layer 120 or scattered inside the damaged layer 120 due to defects 121 in the damaged layer 120, the light detector 300 can detect the reflected or scattered light.

The light detector 300 may include a phototube to detect reflected or scattered light. According to an embodiment, in order to detect light of various wavelengths (or a range of wavelengths, hereinafter referred to as "wavelength"), the light detector 300 may include a plurality of phototubes, or the measuring system 10 may include one or more light detectors 300 having one or more phototubes.

Since the light B is reflected on the surface of the damaged layer 120 or scattered by the defects 121 in the damaged layer 120, the light B detected by the light detector 300 may include the number of defects 121 in the damaged layer 120, the depth of the damaged layer 120 and/or information about the depth of the light B penetrating the damaged layer 120.

Therefore, the determination device (400 in FIG. 2 ) analyzes the detected light B and can determine the concentration of the defect 121 and the depth of the damaged layer 120 according to the penetration depth of the light B. The penetration depth refers to the depth of penetration of the light B, which can be calculated based on the surface of the damaged layer 120 (the surface opposite to the surface connected to the substrate 110).

The absorption depth of light B may vary depending on the wavelength of light B. More specifically, the longer the wavelength of light B, the deeper the absorption depth of light B. For example, the absorption depth of red light with a wavelength of 630-780nm is 350~1000um, the absorption depth of green light with a wavelength of 495-570nm is 90~200um, and the absorption depth of blue light with a wavelength of 450~495nm may be 40~90um, but is not limited thereto.

The absorption depth refers to the depth at which the light B irradiated by the light irradiator 200 penetrates the damaged layer 120 of the characteristic depth and is absorbed by the damaged layer 120. The intensity of the light B can refer to the depth at which the initial intensity reaches 36% (i.e., 1/e). At this time, when the light B that penetrates to the same degree as the absorption depth is reflected or scattered by the defect 121 in the damaged layer 120 and detected by the light detector 300, the intensity of the light B detected by the light detector 130 can be 13% of the initial intensity (=36%*36%).

In this specification, for the sake of convenience, the maximum depth detectable in the light detector 300 is described based on 1 absorption depth, but it is not limited to this. That is, according to the embodiment, the maximum depth detectable in the light detector 300 can have other values besides 1 absorption depth.

The determination device (400 in FIG. 2 ) can analyze a plurality of lights having different wavelengths to determine the distribution degree of the defects 121 at various depths of the damaged layer 120.

FIG2 is a block diagram conceptually showing the function of a determination device for determining the depth of a damaged layer and the defect concentration in the damaged layer according to an embodiment of the present application.

1 and 2, the determination device 400 may include a defect quantity determination unit 410, a penetration depth determination unit 420, a defect concentration determination unit 430, and a damaged layer depth determination unit 440.

The defect quantity determination unit 410, the penetration depth determination unit 420, the defect concentration determination unit 430, and the damage layer depth determination unit 440 shown in FIG2 are conceptually divided into the functions performed by the device 400 for the purpose of easily explaining the functions of the determination device 400, but are not limited thereto. According to an embodiment, the functions of the defect quantity determination unit 410, the penetration depth determination unit 420, the defect concentration determination unit 430, and the damage layer depth determination unit 440 may be combined/separated and may be implemented as a series of commands included in one program.

The defect quantity determination unit 410 can determine the quantity or concentration of defects in the damaged layer 120 detected at a predetermined position and range R irradiated with light B using information about light B received from the light detector.

Since the penetration depth of light B varies according to the wavelength of light B, the number or concentration of defects in the damaged layer 120 can be determined according to the wavelength of light B. That is, even if light B is irradiated in the same position and range, when the wavelength of the irradiated light B is different, the number or concentration of defects detected can be different from each other.

The penetration depth determination unit 420 can determine the penetration depth of light B in a predetermined position and range based on the wavelength of light B.

The defect concentration determination unit 430 determines the defect concentration in the damaged layer 120 in a predetermined position, range, and depth using information about a plurality of lights having different wavelengths.

The damaged layer depth determination unit 440 determines the depth of the damaged layer 120 using the degree of defect distribution according to the light penetration depth.

4 , the defect concentration of the damaged layer 120 determined in the defect concentration determination unit 430 can be shown as a graph related to the depth of the damaged layer 120. According to an embodiment, when the graph related to the defect concentration and the depth shows a regular distribution curve, the damaged layer depth determination unit 440 can determine the depth of the damaged layer 120 according to the variation trend of the graph. That is, the damaged layer depth determination unit 440 can estimate the depth of the damaged layer 120 through the defect 121 concentration based on the graph related to the defect concentration and the depth of the damaged layer 120. At this time, when the defect concentration determined in the defect concentration determination unit 430 is less than or equal to the preset lower limit value, the value is judged as noise and cannot be used to estimate the depth of the damaged layer 120.

Furthermore, when the light irradiator 200 irradiates a larger amount of light with finer wavelength differentiation, a curve diagram related to defect concentration and the depth of the damaged layer 120 can be made more accurately, and thus, the accuracy of the estimation of the damaged layer 120 can be increased.

Alternatively, according to other embodiments, the damage layer depth determination unit determines the depth until the defect is found as the damage layer according to the determination of the defect concentration determination unit 430.

Figure 3 shows an example of determining the depth of the damaged layer and the defect concentration within the damaged layer.

Referring to FIG. 1 and FIG. 3 , FIG. 3 (a) shows a cross-sectional view of the damaged layer 120 when viewed from the side, and FIG. 3 (b) shows a cross-sectional view of the damaged layer 120 when viewed from the top.

When the light irradiator 200 irradiates the damaged layer 120 with different wavelengths of red light B_R, green light B_G and blue light B_B in a predetermined range R simultaneously or at different times, the light irradiator 300 can detect the red light B_R, green light B_G and blue light B_B reflected or scattered by defects in the damaged layer 120.

In this specification, for the sake of convenience, although the predetermined range R of the light irradiator 200 irradiating light is represented as a circle, it is not limited to this. That is, the predetermined range R of light irradiation can be various according to the embodiment. Moreover, the range R of light irradiation can be changed according to the embodiment.

When transmitting information about blue light B_B irradiated in a predetermined range R based on the red light B_R detected by the light detector 300, the defect quantity determination unit 410 can determine the number of defects 121 (e.g., 1) related to the penetration depth PD_B of the blue light B_B.

Similarly, when the light detector 300 transmits information about green light B_G irradiated in a predetermined range R, the defect quantity determination unit 410 determines the number of defects 121 (for example, 3) related to the penetration depth PD_G of the green light B_G. When the light detector 300 transmits information about red light B_R irradiated in a predetermined range R, the defect quantity determination unit 410 can determine the number of defects 121 (for example, 6) related to the penetration depth PD_R of the red light B_R.

At this time, since the wavelengths are in the order of red light B_R, green light B_G, and blue light B_B, the penetration depth PD_R of red light B_R is deeper than the penetration depth PD_G of green light B_G, and the penetration depth PD_G of green light B_G can be deeper than the penetration depth PD_B of blue light B_B.

Therefore, the number of defects 121 in the penetration depth PD_G of the green light B_G (e.g., three) includes the number of defects 121 in the transmission depth PD_B of the blue light B_B (e.g., one), and the value (e.g., two) obtained by subtracting the number of defects 121 in the penetration depth PD_B of the blue light B_B from the number of defects 121 in the penetration depth PD_G of the green light B_G (e.g., three) determines the number or concentration of defects in the second area A2, and the number or concentration of defects in the first area A1 (e.g., one) can be determined as the number of defects 121 of the blue light B_B having the penetration depth PD_B corresponding to the first area A1 (e.g., one).

Similarly, the number of defects 121 in the penetration depth PD_R of the red light B_R (e.g., six) includes the number of defects 121 in the penetration depth PD_G of the green light B_G (e.g., three), and the value (e.g., three) obtained by subtracting the number of defects 121 in the penetration depth PD_G of the green light B_G (e.g., three) from the number of defects 121 in the penetration depth PD_R of the red light B_R (e.g., six) can be determined as the number or concentration of defects in the third area A3.

Through the above process, the number of defects 121 can be determined in the first area A1, the second area A2 and the third area A3 respectively, and the defect concentration in each area can be determined according to the correlation between the volume of each area and the number of defects 121.

Moreover, by irradiating another or more lights to the damaged layer 120 with a penetration depth, the number or concentration of defects in a more finely differentiated area can be known. When the same process is performed while moving the position (x, y) where the light irradiator 200 irradiates the light, the number of defects 121 related to the entire damaged layer 120, the defect concentration, and the depth of the damaged layer can be known.

FIG5 shows a method for measuring the depth of a damaged layer and the defect concentration in the damaged layer when a light irradiator irradiates multiple lights with different wavelengths according to an embodiment of the present application.

Referring to FIG. 1 , FIG. 2 and FIG. 5 , the light irradiator 200 irradiates the damaged layer 120 with light of different wavelengths, and the light detector 300 can detect the light reflected or scattered by the surface or internal defects 121 of the damaged layer 120 .

The light irradiator 200 may sequentially irradiate light with different wavelengths to the damaged layer 120. For example, the light irradiator 200 may irradiate blue light B_B to the first vision, and may irradiate red light B_R to the second vision after the first vision. In this specification, although it is illustrated that one light irradiator 200 sequentially irradiates light with different wavelengths, it is not limited thereto. That is, according to an embodiment, two or more light irradiators 200 may irradiate light with different wavelengths, respectively.

The light detector 300 can detect the blue light B_B and the red light B_R reflected or scattered by the defect 121 in sequence. In this specification, although it is illustrated that two light detectors 300 detect the blue light B_B and the red light B_R respectively, it is not limited to this. That is, according to the embodiment, a light detector 300 including one or more photoelectric tubes can detect both the blue light B_B and the red light B_R.

When the light detector 300 transmits information about the blue light B_B and information about the red light B_R in sequence, as shown in FIG2 , the determination device 400 can determine the number of defects in the damaged layer 120 , the defect concentration, and the depth of the damaged layer 120 using the received information about the blue light B_B and the received information about the red light B_R.

FIG6 shows a method for measuring the depth of a damaged layer and the defect concentration in the damaged layer when a light irradiator irradiates a light having different wavelengths according to an embodiment of the present application.

Referring to FIG. 1 , FIG. 2 and FIG. 6 , the light irradiator 200 'irradiates a light (e.g., white light) that can be dispersed into a plurality of lights having a plurality of different wavelengths onto the damaged layer 120, and the light detector 300 can detect the light reflected or scattered by the defect 121 on the surface or inside of the damaged layer 120.

The light detector 300 can detect the blue light B_B and the red light B_R reflected or scattered by the defect 121. In this specification, a light detector 300 including a plurality of photoelectric tubes is illustrated as being able to detect the blue light B_B, the green light B_G, and the red light B_R, but is not limited thereto. That is, according to the embodiment, the measuring system 10' includes a plurality of light detectors 300, and the plurality of light detectors 300 can detect one light respectively.

When the light detector 300 transmits information about the blue light B_B and information about the red light B_R, as shown in FIG2 , the determination device 400 can determine the number of defects in the damaged layer 120, the defect concentration, and the depth of the damaged layer 120 using the received information about the blue light B_B and the received information about the red light B_R.

FIG7 shows a flow chart of a method for determining the depth of a damaged layer and the defect concentration within the damaged layer according to an embodiment of the present application.

Referring to FIG. 1 , FIG. 2 and FIG. 7 , when the light irradiator 200 irradiates the light B onto the damaged layer 120 ( S700 ), the light detector 300 can detect the light reflected or scattered by the surface or internal defect 121 of the damaged layer 120 ( S710 ).

When the determination device 400 receives information about the light B from the light detector 300, the defect quantity determination unit 410 can determine the quantity or concentration of defects in the damaged layer 120 detected in the predetermined position and range of the irradiated light B using the information about the light B (S720).

The penetration depth determination unit 420 may determine the penetration depth of light B based on the wavelength of light B (S730).

The defect concentration determination unit 430 uses a plurality of lights with different wavelengths to determine the defect concentration in the damaged layer 120 at a predetermined position, range, and depth (S740).

The damaged layer depth determination unit 440 can determine the depth of the damaged layer 120 using the defect concentration according to the depth of the damaged layer 120 determined by the defect concentration determination unit 430 (S750).

The combination of each structure of the structure diagram and each step of the flowchart attached herein can be executed by computer program instructions. These computer program instructions can be mounted on a coding processor of a general-purpose computer, a special-purpose computer or other programmable data processing device, and the instructions executed by the coding processor of the computer or other programmable data processing device generate means for executing the functions described in each structure of the structure diagram or each step of the flowchart. In order to realize functions in a specific way, these computer program instructions can also store computer-usable functions or computer-readable functions that can be directed to computers or other programmable data processing devices in a memory. These instructions stored in computer-usable or computer-readable function memory can also produce products containing instruction means that can execute the functions described in each structure of the structure diagram or each step of the flowchart. Computer program instructions can be mounted on a computer or other programmable data processing device, or they can be executed on a computer or other programmable data processing device to perform a series of operation steps to generate a process executed by the computer. The instructions for executing a computer or other programmable data processing device can also be provided as steps to execute the functions described in each structure of the structure diagram and each step of the flowchart.

Moreover, each structure or each step includes a module of one or more executable instructions for performing a specific logical function, which can represent a section or part of a code. Furthermore, it should be noted that in some alternative embodiments, the functions mentioned in the structure or step can also occur out of sequence. For example, two structures or steps shown one after another can actually be executed substantially at the same time, or sometimes these structures or steps can be executed in reverse order according to the corresponding functions.

The above description is only an example of the technical idea of the present invention. People with ordinary knowledge in the field to which the present invention belongs can make various modifications and changes within the scope of the essence of the present invention. Therefore, the embodiments disclosed in the present invention are not used to limit the technical idea of the present invention, but to illustrate that the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be based on the attached claims, and all technical ideas within the scope equivalent to them shall be understood to be included in the scope of protection of the present invention.

10: Measurement system

110: Substrate

111: Above

112: Back

120: Damage layer

121: Defects

200: Light irradiator

300: Light detector

t:Damage layer depth

B: Light

Claims (8)

A method for determining the depth of a damaged layer, wherein the method is a method for determining the depth of a damaged layer formed on the back side of a substrate, comprising: irradiating the damaged layer with a first light and a second light having a wavelength different from the first light; detecting the first light and the second light reflected or scattered by defects in the damaged layer; determining a first penetration depth of the first light and a second penetration depth of the second light based on a first wavelength of the first light and a second wavelength of the second light; determining the number or concentration of defects in a first area corresponding to the first penetration depth using the detected first light; determining the number or concentration of defects in a second area corresponding to the second penetration depth using the detected second light; and determining the number or concentration of defects in a second area corresponding to the second penetration depth using the detected second light. The step of determining the number or concentration of defects in a third region in the first region that is not included in the second region based on the number or concentration of defects in the first region and the number and concentration of defects in the second region; the step of determining the defect concentration in the first region using the number or concentration of defects in the first region; and the step of determining the defect concentration in the second region using the number or concentration of defects in the second region. The step of determining the defect concentration in the second region by using the number or concentration of defects existing in the third region; the step of determining the defect concentration in the third region by using the number or concentration of defects existing in the third region; and the step of determining the depth of the damaged layer based on a normal distribution curve diagram related to defect concentration and depth of the damaged layer and the defect concentrations existing in the first region, the second region and the third region respectively. A method for determining the depth of a damaged layer according to claim 1, wherein when the first wavelength is longer than the second wavelength, the first penetration depth is deeper than the second penetration depth. According to the method for determining the depth of the damaged layer described in claim 2, the step of determining the depth of the damaged layer is: when a first information shown by the detected first light is the same as a second information shown by the detected second light, the second penetration depth is determined as the depth of the damaged layer. According to the method for determining the depth of the damaged layer described in claim 2, the step of determining the depth of the damaged layer is: when the number or concentration of defects related to the first penetration depth is the same as the number or concentration of defects related to the second penetration depth, the second penetration depth is determined as the depth of the damaged layer. The method for determining the depth of the damaged layer as described in claim 1, wherein the step of irradiating the first light and the second light is: irradiating the first light and the second light to the damaged layer at the same time; the first light and the second light are lights dispersed from white light. The method for determining the depth of the damaged layer as described in claim 1, wherein the step of irradiating the first light and the second light is: irradiating the first light and the second light in sequence. A method for determining the depth of a damaged layer as described in claim 1, wherein the substrate is a silicon substrate. A measuring system, wherein the measuring system is a measuring system for determining the depth of a damaged layer formed on the back side of a substrate, comprising: a light irradiator, irradiating a first light and a second light having a wavelength different from the first light to the damaged layer; a light detector, detecting the first light and the second light reflected or scattered by defects in the damaged layer; and a determining device, receiving information about the first light and information about the second light from the light detector; the determining device, based on a first wavelength of the first light and a second wavelength of the second light, determines a first penetration depth of the first light and a second penetration depth of the second light; using the detected first light, determines the number or concentration of defects existing in a first area corresponding to the first penetration depth; using the detected second light, determines the number or concentration of defects existing in a first area corresponding to the second penetration depth. The method comprises the steps of determining the number or concentration of defects existing in a second region of the first region; determining the number or concentration of defects existing in a third region in the first region that is not included in the second region by using the number or concentration of defects existing in the first region and the number or concentration of defects existing in the second region; determining the defect concentration in the first region by using the number or concentration of defects existing in the first region; and determining the defect concentration in the first region by using the number or concentration of defects existing in the first region. The method comprises the steps of determining the defect concentration in the second region based on the number or concentration of defects existing in the second region; determining the defect concentration in the third region based on the number or concentration of defects existing in the third region; and determining the depth of the damaged layer based on a normal distribution curve diagram of defect concentration and depth of the damaged layer and the defect concentrations existing in the first region, the second region and the third region respectively.