Apparatus and method for inspecting semiconductor substrate using terahertz wave

Abstract

Provided is an apparatus for inspecting a semiconductor substrate using a terahertz wave. The apparatus for inspecting a semiconductor substrate using a terahertz wave comprises: an emitter generating terahertz waves toward a semiconductor substrate; a detector detecting the terahertz wave generated from the emitter and reflected from the semiconductor substrate or the terahertz wave passing through the semiconductor substrate; and an inspection unit inspecting a crack generated in the semiconductor substrate in real time on the basis of the terahertz wave detected by the detector while a semiconductor process is in progress. The crack may include a surface crack of the semiconductor substrate and an internal crack generated inside the semiconductor substrate in the thickness direction.

Description

Semiconductor substrate inspection device and method using terahertz waves

[0001] The present invention relates to a semiconductor substrate inspection apparatus and method using terahertz waves, and more specifically, to a semiconductor substrate inspection apparatus and method using terahertz waves capable of inspecting defects (cracks) generated on a semiconductor substrate in real time while a semiconductor process is in progress.

[0002] Currently, advanced semiconductor processes are implementing 3D integrated circuits by forming multiple vias on a glass substrate and then plating through filling.

[0003] At this time, in conventional semiconductor processes, various reliability problems such as electrical connection failure, warpage, and reduced TC life occurred due to defects in the via formation process and microdefects in the redistribution layer and protective film stacking process.

[0004] Accordingly, conventionally, glass substrates were inspected through laser thermography and visual inspection.

[0005] However, when inspecting glass substrates using a device utilizing laser thermal imaging, it was difficult to pinpoint the exact location of defects due to thermal diffusion, and there were limitations in detecting defects occurring in the depth direction.

[0006] In addition, visual inspection was sensitive to changes in shading, which presented a problem that made accurate defect inspection difficult.

[0007] The technical problem that the present invention aims to solve is to provide a semiconductor substrate inspection device and method using terahertz waves that can inspect defects (cracks) generated on a semiconductor substrate in real time while a semiconductor process is in progress.

[0008] The technical problems that the present invention aims to solve are not limited to those described above.

[0009] To solve the above technical problem, the present invention provides a semiconductor substrate inspection device using terahertz waves.

[0010] According to one embodiment, the semiconductor substrate inspection device using the terahertz waves comprises: an emitter that generates terahertz waves toward a semiconductor substrate; a detector that detects terahertz waves generated from the emitter and reflected from the semiconductor substrate or terahertz waves transmitted through the semiconductor substrate; and an inspection unit that inspects defects (cracks) generated in the semiconductor substrate in real time based on the terahertz waves detected by the detector while the semiconductor process is in progress, wherein the defects may include surface defects of the semiconductor substrate and internal defects generated in the thickness direction within the semiconductor substrate.

[0011] According to one embodiment, the inspection unit can visualize the terahertz waves detected by the detector to identify defects generated on the semiconductor substrate.

[0012] According to one embodiment, the inspection unit inspects for defects occurring on the semiconductor substrate based on the amplitude change of the terahertz waves detected by the detector over the detection time, and can filter the terahertz waves detected by the detector.

[0013] According to one embodiment, the inspection unit can convert the terahertz waves, which are displayed in the time domain, into the frequency domain through signal processing of the terahertz waves detected by the detector.

[0014] According to one embodiment, the inspection unit can perform cepstrum analysis on the terahertz waves converted into the frequency domain.

[0015] According to one embodiment, in the semiconductor substrate, the region where the defect occurs has a relatively larger refractive index (n) than the normal region, but the refractive index (n) for each region where the defect occurs may differ depending on the type of defect.

[0016] According to one embodiment, the inspection unit calculates the refractive index (n) of the semiconductor substrate through the time difference (Δt) when the terahertz wave passing through the air and the terahertz wave passing through the semiconductor substrate reach the detector and the thickness (d) of the semiconductor substrate, and inspects defects occurring in the semiconductor substrate in real time based on the calculated refractive index (n) of the semiconductor substrate, wherein the refractive index (n) of the semiconductor substrate can be calculated through the following formula 1.

[0017]

[0018] [Formula 1]

[0019]

[0020]

[0021] Here, c is the speed of light.

[0022] According to one embodiment, the emitter and detector are configured to operate in any one of a reflection mode, a transmission mode, and a tilted transmission mode based on the optical path of the terahertz wave to the semiconductor substrate. In the reflection mode, the emitter and detector are arranged to be symmetrically positioned on the upper side of the semiconductor substrate based on the normal direction of the semiconductor substrate. In the transmission mode, the emitter and detector are each arranged on the upper and lower sides of the semiconductor substrate, respectively, in the normal direction of the semiconductor substrate. In the tilted transmission mode, the emitter is arranged to be tilted from the normal direction of the semiconductor substrate on the upper side of the semiconductor substrate, with the tilting angle adjustable, and the detector is arranged on the lower side of the semiconductor substrate to correspond to the same line as the emitter based on the optical path.

[0023] According to one embodiment, in the case of the tilted transmission mode, the emitter and detector can scan while changing the optical path of the terahertz waves that transmit the internal defect.

[0024] According to one embodiment, the apparatus further includes a first optical apparatus and a second optical apparatus, wherein the first optical apparatus is positioned between the emitter and the semiconductor substrate and the second optical apparatus is positioned between the semiconductor substrate and the detector, and terahertz waves generated from the emitter are irradiated onto the semiconductor substrate through the first optical apparatus and then guided to the detector by the second optical apparatus, and by adjusting the angles of the first optical apparatus and the second optical apparatus, rapid scanning of the entire surface area of ​​the semiconductor substrate may be possible.

[0025] According to one embodiment, while the emitter and detector are fixed, scanning of the entire surface area of ​​the semiconductor substrate may be possible by moving and rotating the semiconductor substrate.

[0026] According to one embodiment, the semiconductor substrate may be any one of a group of substrate candidates including a silicon wafer, a glass substrate, and a plastic substrate.

[0027] According to one embodiment, the emitter and detector are provided with at least one each, and may be provided in a corresponding number.

[0028] Meanwhile, the present invention provides a method for inspecting a semiconductor substrate using terahertz waves.

[0029] According to one embodiment, the semiconductor substrate inspection method using terahertz waves comprises: a step of generating terahertz waves toward a semiconductor substrate; a step of detecting terahertz waves reflected from the semiconductor substrate or terahertz waves transmitted through the semiconductor substrate; and a step of inspecting defects (cracks) generated in the semiconductor substrate in real time based on the terahertz waves detected in the step of detecting terahertz waves while the semiconductor process is in progress, wherein the defects may include surface defects of the semiconductor substrate and internal defects generated in the thickness direction within the semiconductor substrate.

[0030] According to an embodiment of the present invention, the apparatus comprises: an emitter that generates terahertz waves toward a semiconductor substrate; a detector that detects terahertz waves generated from the emitter and reflected from the semiconductor substrate or terahertz waves transmitted through the semiconductor substrate; and an inspection unit that inspects a defect (crack) generated in the semiconductor substrate in real time based on the terahertz waves detected by the detector while the semiconductor process is in progress, wherein the defect may include a surface defect of the semiconductor substrate and an internal defect generated in the thickness direction within the semiconductor substrate.

[0031] Accordingly, a semiconductor substrate inspection device and method using terahertz waves can be provided, which can inspect defects (cracks) occurring on a semiconductor substrate in real time while the semiconductor process is in progress.

[0032] At this time, according to an embodiment of the present invention, identification based on the presence or absence of defects and the type of defects may also be possible through the difference in refractive index by region of the semiconductor substrate.

[0033] The semiconductor substrate inspection method according to the embodiment of the present invention can also be applied to various processes for processing substrates, such as deposition and plating processes.

[0034] FIG. 1 is a schematic diagram illustrating a semiconductor substrate inspection device according to one embodiment of the present invention.

[0035] FIG. 2 is a schematic diagram illustrating a semiconductor substrate being inspected through a semiconductor substrate inspection device according to one embodiment of the present invention.

[0036] FIGS. 3 to 6 are schematic diagrams illustrating the reflection mode of a semiconductor substrate inspection device according to one embodiment of the present invention.

[0037] FIG. 7 is a schematic diagram illustrating the transmission mode of a semiconductor substrate inspection device according to one embodiment of the present invention.

[0038] FIG. 8 is a schematic diagram illustrating the tilted transmission mode of a semiconductor substrate inspection device according to one embodiment of the present invention.

[0039] FIG. 9 is an image visualized by filtering terahertz waves detected by a detector when a semiconductor substrate inspection device according to one embodiment of the present invention is in transmission mode.

[0040] FIG. 10 is an image visualizing terahertz waves detected by a detector in a transmission mode when a semiconductor substrate inspection device according to one embodiment of the present invention is in a cepstrum mode.

[0041] FIG. 11 is a graph showing a comparison of the refractive indices of normal and defective regions calculated by the inspection unit of a semiconductor substrate inspection device according to one embodiment of the present invention.

[0042] FIG. 12 is a flowchart illustrating a semiconductor substrate inspection method according to one embodiment of the present invention.

[0043] Figure 13 is a diagram showing defects made on a glass substrate prepared according to Experimental Example 1.

[0044] Figure 14 is a photograph of a glass substrate inspection device according to Experimental Example 1.

[0045] Figures 15 to 19 are the results of the analysis of glass substrate defects examined according to Experimental Example 1.

[0046] Figure 20 is a photograph of a glass substrate inspection device according to Experimental Example 2.

[0047] FIG. 21 is a drawing showing defects made on a glass substrate prepared according to Example 2.

[0048] Figure 22 shows the results of the defect analysis of a glass substrate inspected according to Experimental Example 2.

[0049] Figure 23 is a photograph of a glass substrate inspection device according to Experimental Example 3.

[0050] Figure 24 is a schematic diagram illustrating a glass substrate inspection device according to Experimental Example 3.

[0051] Figures 25 to 30 are the results of the analysis of glass substrate defects examined according to Experimental Example 3.

[0052] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art.

[0053] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, shapes and sizes are exaggerated for the effective illustration of the technical content.

[0054] Additionally, although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. Accordingly, what is referred to as the first component in one embodiment may be referred to as the second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. Furthermore, in this specification, "and / or" is used to mean including at least one of the components listed before and after it.

[0055] In the specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, components, or combinations thereof described in the specification, and should not be understood as excluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. Additionally, in this specification, "connection" is used to include both indirectly connecting multiple components and directly connecting them.

[0056] Additionally, terms such as “…part,” “…unit,” and “module” described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0057] In addition, in describing the present invention below, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0058]

[0059] FIGS. 1 to 11 are drawings for explaining a semiconductor substrate inspection device according to an embodiment of the present invention.

[0060]

[0061] As illustrated in FIG. 1, a semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention is a device that inspects defects (cracks) that occur on a semiconductor substrate (S) in real time while a semiconductor process is in progress.

[0062] Here, the semiconductor substrate (S) that is inspected in real time by the semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention may be any one of a group of substrate candidates including a silicon wafer, a glass substrate, and a plastic substrate.

[0063] As illustrated in FIG. 2, for example, when the semiconductor substrate (S) is a glass substrate, in the semiconductor process, a femtosecond or picosecond laser is first irradiated onto the surface of the glass substrate to create an internal strain region, and the glass substrate with the internal strain region created is immersed in an etching solution such as hydrofluoric acid (HF), NH4F, or KOH to perform anisotropic etching.

[0064] Accordingly, the laser-deformed area is rapidly etched to form vias on the glass substrate, and in this process, many micro-defects occur on the glass substrate.

[0065] Next, in the semiconductor process, a metal seed layer is deposited on the surface of the glass substrate and the inner wall of the via by sputtering, and plating is performed to fill the surface of the glass substrate and the via.

[0066] Next, in the semiconductor process, the plating deposited on the surface of the glass substrate is removed through Chemical Mechanical Polishing (CMP).

[0067] Next, in the semiconductor process, a redistribution layer (RDL) and a solder resist passivation layer are sequentially deposited on the surface of the glass substrate, but many microdefects occur on the glass substrate during this process as well.

[0068] Finally, in the semiconductor manufacturing process, the manufactured glass interposer is diced, and many microdefects occur during this process as well.

[0069] As such, various defects occurring on the glass substrate during the semiconductor manufacturing process cause reliability issues with the manufactured glass interposer.

[0070] Here, during the semiconductor process, defects occurring on the semiconductor substrate (S) may include surface defects (Surface crack; SC) occurring on the surface of the semiconductor substrate (S) and internal defects (Vertical crack; VC) occurring in the thickness direction, for example, in the vertical direction, inside the semiconductor substrate (S).

[0071] Accordingly, a semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention can inspect defects occurring on a semiconductor substrate (S) in real time while the semiconductor process is in progress, thereby enabling immediate response when defects occur during the semiconductor process.

[0072] That is, the semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention can inspect defects occurring on the semiconductor substrate (S) in real time while the semiconductor process is in progress, thereby enabling active measures to be taken to improve yield while the semiconductor process is in progress.

[0073] That is, the semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention can enable the manufacture of a glass interposer of excellent quality by inspecting defects that occur on the semiconductor substrate (S) in real time while the semiconductor process is in progress.

[0074]

[0075] To this end, a semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention may include an emitter (110), a detector (120), and an inspection unit (130).

[0076]

[0077] The emitter (110) is a device that generates terahertz waves toward a semiconductor substrate (S). To this end, the emitter (110) may be positioned to face the semiconductor substrate (S).

[0078] As shown in FIG. 3, the emitter (110) may be positioned at a set angle of inclination from the normal direction of the semiconductor substrate (S). For example, the emitter (110) may be positioned at a 30-degree angle of inclination from the normal direction of the semiconductor substrate (S).

[0079] Accordingly, the terahertz waves generated from the emitter (110) can be incident on the semiconductor substrate (S) at a 60-degree angle relative to the semiconductor substrate (S).

[0080] At this time, the semiconductor substrate (S) to which the terahertz waves generated from the emitter (110) are incident may be in the process of undergoing a semiconductor process, such as forming vias, plating, CMP, or forming a redistribution layer.

[0081] According to one embodiment of the present invention, the terahertz wave generated from the emitter (110) and irradiated toward the semiconductor substrate (S) may be provided as a pulsed type or a continuous wave.

[0082] Here, pulsed terahertz waves have the advantage of being able to detect at once because they contain numerous frequencies.

[0083] To generate such pulsed terahertz waves, a femtosecond laser that functions as a pump light for generating pulsed terahertz waves can be irradiated onto the emitter (110).

[0084] In addition, according to one embodiment of the present invention, the frequency of the terahertz waves generated from the emitter (110) and irradiated onto the semiconductor substrate (S) may be 0.1 THz to 10 THz.

[0085]

[0086] The detector (120) can detect terahertz waves generated from the emitter (110) and reflected from the semiconductor substrate (S).

[0087] That is, according to one embodiment of the present invention, the detector (120) may be configured to operate in a reflection mode together with the emitter (110) based on the optical path of the terahertz wave to the semiconductor substrate (S).

[0088] Accordingly, the detector (120) can be positioned symmetrically with respect to the emitter (110) with respect to the normal direction of the semiconductor substrate (S).

[0089] For example, if the emitter (110) is positioned at a 30-degree angle from the normal direction of the semiconductor substrate (S), the detector (120) may be positioned at -30 degrees from the normal direction of the semiconductor substrate (S) so as to be symmetrical with respect to the emitter (110).

[0090] In this way, when the emitter (110) and the detector (120) are configured to operate in a reflection mode, the detector (120) can detect terahertz waves that are generated from the emitter (110) and reflected from defects, such as surface defects and internal defects, generated on the semiconductor substrate (S).

[0091] At this time, as illustrated in FIG. 3, a semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention can adjust the depth of focus by moving the detector (120) up and down.

[0092] Through this, a semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention can obtain and compare reflection mode data formed at various angles.

[0093] As illustrated in FIG. 4, a semiconductor substrate inspection device (100) according to one embodiment of the present invention may further include a first optical instrument (113) and a second optical instrument (115).

[0094] The first optical device (113) can be placed in the optical path of the terahertz waves irradiated from the emitter (110) onto the semiconductor substrate (S).

[0095] That is, the first optical device (113) can be provided between the emitter (110) and the semiconductor substrate (S).

[0096] The second optical device (115) above may be placed in the optical path of the terahertz waves that are reflected from the semiconductor substrate (S) and received by the detector (120).

[0097] That is, the second optical device (115) can be provided between the semiconductor substrate (S) and the detector (120).

[0098] Accordingly, the terahertz waves generated from the emitter (110) can be irradiated onto the semiconductor substrate (S) through the first optical device (113) and then guided to the detector (120) by the second optical device (115).

[0099] At this time, according to one embodiment of the present invention, the angles of the first optical mechanism (113) and the second optical mechanism (115) disposed on the optical path of the terahertz wave can be adjusted.

[0100] In this way, by adjusting the angles of the first optical device (113) and the second optical device (115), the optical paths of the terahertz waves irradiated onto the semiconductor substrate (S) and the terahertz waves reflected from the semiconductor substrate (S) can be adjusted.

[0101] Accordingly, according to one embodiment of the present invention, terahertz waves can be irradiated over the entire surface of a semiconductor substrate (S) without moving the semiconductor substrate (S).

[0102] Through this, rapid inspection can be performed by rapidly scanning the entire surface area of ​​the semiconductor substrate (S).

[0103] Meanwhile, as shown in FIG. 5, the emitter (110) and detector (120) operating in reflection mode can be fixed.

[0104] In this way, with the emitter (110) and detector (120) fixed, the semiconductor substrate (S) can be moved, and through this, the entire surface area of ​​the semiconductor substrate (S) can be scanned.

[0105] In addition, as shown in FIG. 6, the semiconductor substrate (S) can be rotated while the emitter (110) and the detector (120) are fixed, and through this, scanning of the entire surface area of ​​the semiconductor substrate (S) is possible, and the possibility of inspecting undetected defects can be increased.

[0106] At this time, the movement and rotation of the semiconductor substrate (S) can be achieved by the movement and rotation of the stage on which the semiconductor substrate (S) is placed.

[0107] Meanwhile, as illustrated in FIG. 7, according to one variant of the present invention, the emitter (110) and the detector (120) may be configured to operate in a transmission mode based on the optical path to the semiconductor substrate (S).

[0108] To this end, the emitter (110) may be positioned facing the semiconductor substrate (S) in a normal direction, and the detector (120) may be positioned on the lower side of the semiconductor substrate (S) in a normal direction to the semiconductor substrate (S).

[0109] That is, according to one variant of the present invention, the detector (120) may be positioned in a direction facing the emitter (110) while being aligned with the emitter (110) with the semiconductor substrate (S) in between.

[0110] Accordingly, the terahertz waves generated from the emitter (110) can pass through the semiconductor substrate (S) and be detected by the detector (120).

[0111] Additionally, as illustrated in FIG. 8, according to another variation of the present invention, the emitter (110) and the detector (120) may be configured to operate in a tilted transmission mode with respect to the optical path to the semiconductor substrate (S).

[0112] To this end, the emitter (110) can be tilted from the normal direction of the semiconductor substrate (S) on the upper side of the semiconductor substrate (S).

[0113] For example, the emitter (110) can be tilted 13 degrees from the normal direction of the semiconductor substrate (S) on the upper side of the semiconductor substrate (S).

[0114] However, this is merely an example, and the tilting angle of the emitter (110) is not necessarily limited to 13 degrees. That is, the emitter (110) can be positioned on the upper side of the semiconductor substrate (S) to allow for tilting angle adjustment.

[0115] In addition, the detector (120) can be positioned on the lower side of the semiconductor substrate (S) so as to correspond to the emitter (110) along the optical path.

[0116] According to one embodiment of the present invention, in the case of a tilted transmission mode, the emitter (110) and the detector (120) can scan while changing the optical path of the terahertz waves that transmit internal defects generated in the semiconductor substrate (S).

[0117] That is, in the case of the tilted transmission mode, the emitter (110) and the detector (120) can scan internal defects occurring on the semiconductor substrate (S) as surfaces rather than lines by adjusting the tilting angle.

[0118] Accordingly, transmission data at various angles can be compared and analyzed, and through this, it may be possible to accurately detect internal defects that are not visible to the naked eye.

[0119] According to one embodiment of the present invention, one or more of these emitters (110) and detectors (120) may be provided.

[0120] At this time, when the emitter (110) and the detector (120) are each provided in pairs, the emitter (110) and the detector (120) may be provided in corresponding numbers to form pairs.

[0121] In this way, if two or more emitters (110) and detectors (120) are provided, the inspection speed for defects occurring on the semiconductor substrate (S) during the semiconductor process can be significantly improved.

[0122]

[0123] The inspection unit (130) can inspect defects occurring on the semiconductor substrate (S) in real time based on terahertz waves detected by the detector (120) while the semiconductor process is in progress.

[0124] That is, the inspection unit (130) can inspect surface defects generated on the surface of the semiconductor substrate (S) and internal defects generated in the thickness direction inside the semiconductor substrate (S) in real time based on terahertz waves detected by the detector (120) during the semiconductor process, the via formation process, the redistribution layer formation process, and the dicing process.

[0125] According to one embodiment of the present invention, the inspection unit (130) can inspect for defects occurring in the semiconductor substrate (S) from the amplitude change according to the detection time of the terahertz wave detected by the detector (120).

[0126] At this time, according to one embodiment of the present invention, the inspection unit (130) can visualize the terahertz waves detected by the detector (120).

[0127] The inspection unit (130) can identify defects occurring on the semiconductor substrate (S) through the terahertz waves visualized in this way.

[0128] That is, the inspection unit (130) can filter the terahertz waves detected by the detector (120).

[0129] For example, the inspection unit (130) can filter the terahertz wave raw data detected by the detector (120) using a band pass filter, visualize the filtered terahertz wave, and observe defects occurring on the semiconductor substrate (S) through image analysis.

[0130] In addition, the inspection unit (130) can convert the terahertz waves, which are displayed in the time domain, into the frequency domain through signal processing of the terahertz waves detected by the detector (120).

[0131] Next, the inspection unit (130) can perform cepstrum analysis on the terahertz waves converted into the frequency domain, visualize the cepstrum-analyzed terahertz waves, and observe defects occurring on the semiconductor substrate (S) through image analysis.

[0132] Meanwhile, surface defects occurring on the surface of the semiconductor substrate (S) can also be identified through differences in refractive index (n) by region of the semiconductor substrate (S).

[0133] That is, as shown in FIG. 11, in a semiconductor substrate (S), the region where surface defects (Surface_crack1, Surface_crack2) occur may have a relatively higher refractive index (n) than the normal region (Normal). This may be due to scattering of terahertz waves caused by defects.

[0134] Accordingly, the inspection unit (130) can determine that a surface defect has occurred in a specific region of the semiconductor substrate (S) if the refractive index (n) of that specific region is greater than the refractive index (n) of the normal region (Normal) that is already recognized.

[0135] At this time, depending on the type of defect, the refractive index (n) of each defect-affected region may differ.

[0136] For example, the refractive index (n) may be different between one surface defect region (Surface_crack1) that occurs on one side surface of the semiconductor substrate (S) and another surface defect region (Surface_crack2) that occurs on the other side surface of the semiconductor substrate (S).

[0137] In this case, the inspection unit (130) can determine that the types of surface defects occurring in both regions are different, and can distinguish the surface defects occurring in both regions of the semiconductor substrate (S) currently being inspected according to type by comparing them with the refractive index (n) of the surface defect types already stored in the database (DB).

[0138] At this time, according to one embodiment of the present invention, the inspection unit (130) can calculate the refractive index (n) of the semiconductor substrate (S) through the time difference (Δt) when the terahertz wave passing through the air and the terahertz wave passing through the semiconductor substrate (S) reach the detector (120) and the thickness (d) of the semiconductor substrate (S).

[0139] And the inspection unit (130) can inspect defects that have occurred on the semiconductor substrate (S), for example, surface defects that have occurred on the surface of the semiconductor substrate (S), in real time based on the calculated refractive index (n) of the semiconductor substrate (S).

[0140] That is, the inspection unit (130) can inspect in real time which region of the semiconductor substrate (S) is a normal region and which region has a defect based on the calculated refractive index (n) of the semiconductor substrate (S).

[0141] At this time, the inspection unit (130) can even distinguish the type of surface defect that occurs on the surface of the semiconductor substrate (S).

[0142] According to one embodiment of the present invention, the refractive index (n) of such a semiconductor substrate (S) can be calculated through the following Equation 1.

[0143]

[0144] [Formula 1]

[0145]

[0146]

[0147] Here, c is the speed of light.

[0148] Meanwhile, as shown in FIGS. 9 and 10, if the density of defects generated in the semiconductor substrate (S) is low, internal defects generated in the depth direction inside the semiconductor substrate (S) may not be observed even if the terahertz waves detected by the detector (120) are filtered by a band-pass filter and visualized through the inspection unit (130) or the cepstrum-analyzed terahertz waves are visualized.

[0149] In this way, when internal defects occurring in the depth direction within the semiconductor substrate (S) are not visible to the naked eye, the emitter (110) and the detector (120) can be operated in a tilted transmission mode.

[0150] Accordingly, the inspection unit (130) can filter the terahertz waves detected by the detector (120) through a tilted transmission mode using a band-pass filter, and then proceed with the cepstrum.

[0151] Through this, the inspection unit (130) can check for internal defects that occur in the depth direction inside the semiconductor substrate (S).

[0152]

[0153] A semiconductor substrate inspection device (100) using terahertz waves according to one embodiment of the present invention can inspect surface defects generated on the surface of a semiconductor substrate (S) and internal defects generated in the thickness direction inside a semiconductor substrate (S) in real time during a semiconductor process, based on terahertz waves detected by a detector (120) through an inspection unit (130) during a semiconductor process.

[0154]

[0155] Hereinafter, a semiconductor substrate inspection method using terahertz waves according to one embodiment of the present invention will be described with reference to FIG. 12.

[0156]

[0157] FIG. 12 is a flowchart illustrating a semiconductor substrate inspection method using terahertz waves according to one embodiment of the present invention.

[0158]

[0159] Referring to FIG. 12, a semiconductor substrate inspection method using terahertz waves according to one embodiment of the present invention may include steps S110, S120, and S130.

[0160]

[0161] S110 step

[0162] The above S110 step is a step of generating terahertz waves toward a semiconductor substrate (S).

[0163] At this time, the above S110 step can generate terahertz waves toward a semiconductor substrate (S) through any one of the measurement modes of reflection mode, transmission mode and tilted transmission mode.

[0164] That is, in the above S110 step, terahertz waves can be generated toward the semiconductor substrate (S) so that terahertz waves are incident on the semiconductor substrate (S) at an angle greater than 0° and less than 90°.

[0165] At this time, the optical path of the terahertz waves irradiated toward the semiconductor substrate (S) can be controlled by an optical device (113, 115) placed on the optical path of the terahertz waves. Accordingly, terahertz waves can be irradiated over the entire surface area of ​​the semiconductor substrate (S).

[0166] In addition, as the semiconductor substrate (S) is moved or rotated on a plane, terahertz waves directed toward the semiconductor substrate (S) can be directed across the entire surface area of ​​the semiconductor substrate (S).

[0167] Meanwhile, in the above S110 step, terahertz waves can be generated so that terahertz waves are incident on the semiconductor substrate (S) in the normal direction of the semiconductor substrate (S).

[0168] In addition, in step S110 above, terahertz waves can be generated so that terahertz waves are incident on the semiconductor substrate (S) at an angle tilted from the normal direction of the semiconductor substrate (S).

[0169] According to one embodiment of the present invention, the terahertz waves irradiated toward the semiconductor substrate (S) may be provided as a pulsed type or a continuous wave.

[0170] At this time, the frequency of the terahertz waves irradiated toward the semiconductor substrate (S) may be 0.1 THz to 10 THz.

[0171]

[0172] S120 step

[0173] The above S120 step is a step of detecting terahertz waves reflected from the semiconductor substrate (S) or terahertz waves transmitted through the semiconductor substrate (S).

[0174] When terahertz waves are generated toward the semiconductor substrate (S) through the reflection mode in step S110 above, in step S120, terahertz waves reflected from the semiconductor substrate (S), more specifically, surface defects generated on the surface of the semiconductor substrate (S) and internal defects generated in the thickness direction inside the semiconductor substrate (S) can be detected.

[0175] In addition, if terahertz waves are generated toward the semiconductor substrate (S) through a transmission mode or a tilted transmission mode in step S110, terahertz waves that penetrate surface defects and internal defects of the semiconductor substrate (S) can be detected in step S120.

[0176] Here, when the density of defects generated on the semiconductor substrate (S) is low, a tilted transmission mode may be preferred.

[0177] Meanwhile, in the above steps S110 and S120, the entire surface area of ​​the semiconductor substrate (S) can be scanned. Accordingly, in step S130, an inspection of the entire surface area of ​​the semiconductor substrate (S) can be performed.

[0178]

[0179] S130 step

[0180] The above S130 step is a step of inspecting defects occurring on a semiconductor substrate (S) in real time based on the terahertz waves detected in the above S120 step while the semiconductor process is in progress.

[0181] That is, in the above S130 step, while the semiconductor process is in progress, surface defects generated on the surface of the semiconductor substrate (S) and internal defects generated in the thickness direction inside the semiconductor substrate (S) can be inspected in real time based on the terahertz waves detected in the above S120 step during the via formation process, the redistribution layer formation process, and the dicing process.

[0182] At this time, in step S130, the terahertz waves detected in step S120 can be visualized, and thus, defects occurring in the semiconductor substrate (S) can be identified through the visualized terahertz waves.

[0183] That is, in step S130, the raw terahertz wave data detected in step S120 can be filtered with a bandpass filter, and the filtered terahertz wave can be visualized and, through image analysis, the defects generated on the semiconductor substrate (S) can be observed.

[0184] In addition, in step S130, the terahertz waves detected in step S120 can be converted into the frequency domain through signal processing.

[0185] Next, in the above S130 step, the terahertz waves converted into the frequency domain can be cepstrum analyzed, the cepstrum-analyzed terahertz waves can be visualized, and defects generated on the semiconductor substrate (S) can be observed through image analysis.

[0186] Meanwhile, in the above S130 step, if the refractive index (n) of a specific region in the semiconductor substrate (S) is greater than the refractive index (n) of a previously recognized normal region, it can be determined that a surface defect has occurred in that region.

[0187] In the above step S130, if the refractive index (n) is different between a surface defect area on one side of the semiconductor substrate (S) and another surface defect area on the other side of the semiconductor substrate (S), it can be determined that the types of surface defects occurring in both areas are different, and by comparing with the refractive index (n) for each type of surface defect already stored in the database (DB), the surface defects occurring in both areas of the semiconductor substrate (S) currently being inspected can be classified according to type.

[0188] At this time, in step S130, the refractive index (n) of the semiconductor substrate (S) can be calculated through the time difference (Δt) between the terahertz waves passing through air and the terahertz waves passing through the semiconductor substrate (S) detected in step S120 and the thickness (d) of the semiconductor substrate (S).

[0189] And in the above S130 step, based on the calculated refractive index (n) of the semiconductor substrate (S), defects occurring on the semiconductor substrate (S), for example, surface defects occurring on the surface of the semiconductor substrate (S), can be inspected in real time.

[0190] That is, in the above S130 step, based on the calculated refractive index (n) of the semiconductor substrate (S), it is possible to inspect in real time which region of the semiconductor substrate (S) is a normal region and which region has a defect.

[0191] At this time, in the above S130 step, even the type of surface defect generated on the surface of the semiconductor substrate (S) can be distinguished.

[0192] According to one embodiment of the present invention, the refractive index (n) of such a semiconductor substrate (S) can be calculated through the following Equation 1.

[0193]

[0194] [Formula 1]

[0195]

[0196]

[0197] Here, c is the speed of light.

[0198] Meanwhile, if the density of defects generated in the semiconductor substrate (S) is low, internal defects generated in the depth direction within the semiconductor substrate (S) may not be observed even if the terahertz waves detected in the S120 step are filtered by a bandpass filter and visualized through the S130 step, or even if the cepstrum-analyzed terahertz waves are visualized.

[0199] In this way, if internal defects occurring in the depth direction within the semiconductor substrate (S) are not visible to the naked eye, the tilted transmission mode can be operated in steps S110 and S120.

[0200] Accordingly, in step S130, the terahertz waves detected in step S120 can be filtered through a band-pass filter via a tilted transmission mode, and then a cepstrum can be performed.

[0201] Through this, in the above S130 step, internal defects occurring in the depth direction within the semiconductor substrate (S) can be identified.

[0202]

[0203] Experiment Example 1

[0204] Referring to Figures 13 and 14, surface defects and internal defects were formed on the glass substrate.

[0205] Surface defects were formed in various sizes ranging from 100㎛ or less to 600㎛ or more. At this time, internal defects were formed so that they are not visible to the naked eye and become visible only when the periphery of the glass substrate is pressed.

[0206] A glass substrate with surface defects and internal defects was inspected using terahertz waves.

[0207] At this time, a glass substrate with surface defects and internal defects formed was inspected in a 60-degree reflection mode.

[0208] Figures 15 to 19 are the results of the analysis of glass substrate defects examined according to Experimental Example 1.

[0209] First, referring to FIGS. 15 and 16, defects formed on a glass substrate can be inspected from the amplitude change of the detected terahertz waves over the detection time.

[0210] At this time, all terahertz waves detected in the optical path of terahertz waves, such as surface reflected waves, internal reflected waves, and multiple reflected waves of terahertz waves, were used for defect inspection formed on a glass substrate.

[0211] Next, referring to Fig. 17, the detected terahertz wave raw data was filtered with a bandpass filter (1-2 THz) and visualized to analyze the image.

[0212] Next, referring to Fig. 18, the terahertz waves, which are displayed in the time domain, were converted into the frequency domain through signal processing of the detected terahertz waves.

[0213] Next, referring to Fig. 19, the image was analyzed by performing a cepstrum on the terahertz waves converted to the frequency domain and visualizing them.

[0214] Analysis results confirmed that surface defects larger than 600 µm were clearly observed with both the bandpass filter and cepstrum techniques, while surface defects smaller than 100 µm were observed, albeit somewhat blurry.

[0215]

[0216] Experiment Example 2

[0217] Referring to FIGS. 20 and FIGS. 21, surface defects and internal defects were formed on a glass substrate.

[0218] Surface defects were formed in various sizes ranging from 100㎛ or less to 600㎛ or more. At this time, internal defects were formed so that they are not visible to the naked eye and become visible only when the periphery of the glass substrate is pressed.

[0219] A glass substrate with surface defects and internal defects was inspected using terahertz waves.

[0220] At this time, the scanning area was set to include more vertical defects, and the glass substrate with surface and internal defects was inspected in transmission mode.

[0221] Figure 22 shows the results of the defect analysis of a glass substrate inspected according to Experimental Example 2.

[0222] Referring to Fig. 22, two surface defects (Surface_crack1, Surface_crack2) were observed, and no internal defects were observed.

[0223] When comparing the refractive index of the normal region and the region with two surface defects (Surface_crack1, Surface_crack2), the refractive index value of the region with surface defects (Surface_crack1, Surface_crack2) was found to be somewhat higher (see Fig. 11). This is attributed to scattering caused by surface defects.

[0224] In addition, it was confirmed that the refractive index differs depending on the type of surface defect (Surface_crack1, Surface_crack2).

[0225] As such, it was confirmed that surface defects (Surface_crack1, Surface_crack2) can be distinguished from the normal region, and that the two surface defects (Surface_crack1, Surface_crack2) can also be distinguished by type through the difference in refractive index.

[0226] However, due to the low defect density, no vertical defects were observed even when filtered with a bandpass filter (see Fig. 9) and when cepstrum analyzed (see Fig. 10).

[0227]

[0228] Experiment Example 3

[0229] Referring to FIGS. 23 and 24, surface defects and internal defects were formed on the glass substrate.

[0230] Surface defects were formed in various sizes ranging from 100㎛ or less to 600㎛ or more. At this time, internal defects were formed so that they are not visible to the naked eye and become visible only when the periphery of the glass substrate is pressed.

[0231] A glass substrate with surface defects and internal defects was inspected using terahertz waves.

[0232] At this time, to detect vertical defects that are not visible to the naked eye, a glass substrate with surface defects and internal defects was inspected in a tilted transmission mode.

[0233] At this time, scanning was performed by tilting the terahertz waves irradiated onto the glass substrate by 13 degrees to change the optical path of the terahertz waves passing through the internal defect surface.

[0234] Figures 25 to 30 are the results of the analysis of glass substrate defects examined according to Experimental Example 3.

[0235] Referring to FIGS. 25 to 28, a band-pass filter and a cepstrum were performed, similar to Experimental Example 1 and Experimental Example 2.

[0236] Referring to Fig. 29, at a quefrency index of 3.76, sharp surface defects (S.C1, S.C2) and some blurry internal defects (V.C1, V.C2) were identified, and point data for each identified defect was extracted and compared with the cepstrum signal.

[0237] Referring to Fig. 30, it was confirmed that the signal difference due to defects on the cepstrum signal is not significant, but the possibility of detecting minute internal defects was confirmed.

[0238]

[0239] Although the present invention has been described in detail using preferred embodiments, the scope of the invention is not limited to specific embodiments and should be interpreted by the appended claims. Furthermore, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the invention.

Claims

1. An emitter that generates terahertz waves toward a semiconductor substrate; A detector for detecting terahertz waves generated from the emitter and reflected from the semiconductor substrate or terahertz waves transmitted through the semiconductor substrate; and Including an inspection unit that inspects defects (cracks) generated on the semiconductor substrate in real time based on terahertz waves detected by the detector while the semiconductor process is in progress; A semiconductor substrate inspection device using terahertz waves, wherein the defects include surface defects of the semiconductor substrate and internal defects generated in the thickness direction within the semiconductor substrate.

2. In Paragraph 1, The above inspection unit is a semiconductor substrate inspection device using terahertz waves, which visualizes terahertz waves detected by the detector to identify defects generated on the semiconductor substrate.

3. In Paragraph 2, A semiconductor substrate inspection device using terahertz waves, wherein the inspection unit inspects defects occurring on the semiconductor substrate from changes in amplitude according to the detection time of the terahertz waves detected by the detector, and filters the terahertz waves detected by the detector.

4. In Paragraph 2, A semiconductor substrate inspection device using terahertz waves, wherein the inspection unit converts terahertz waves represented in the time domain into the frequency domain through signal processing of terahertz waves detected by the detector.

5. In Paragraph 4, The above inspection unit is a semiconductor substrate inspection device using terahertz waves that performs cepstrum analysis of terahertz waves converted into the frequency domain.

6. In Paragraph 1, A semiconductor substrate inspection device using terahertz waves, wherein the region where the defect occurs in the semiconductor substrate has a relatively higher refractive index (n) than the normal region, and the refractive index (n) for each region where the defect occurs differs depending on the type of defect.

7. In Paragraph 6, The inspection unit calculates the refractive index (n) of the semiconductor substrate through the time difference (Δt) between the terahertz wave passing through air and the terahertz wave passing through the semiconductor substrate reaching the detector and the thickness (d) of the semiconductor substrate, and inspects defects occurring in the semiconductor substrate in real time based on the calculated refractive index (n) of the semiconductor substrate. A semiconductor substrate inspection device using terahertz waves, wherein the refractive index (n) of the semiconductor substrate is calculated through the following Equation 1. [Formula 1] Here, c is the speed of light.

8. In Paragraph 1, The emitter and detector are configured to operate in any one of a measurement mode, a reflection mode, a transmission mode, and a tilted transmission mode, based on the optical path of the terahertz wave to the semiconductor substrate, wherein In the above reflection mode, the emitter and detector are arranged symmetrically on the upper side of the semiconductor substrate with respect to the normal direction of the semiconductor substrate, and In the above transmission mode, the emitter and the detector are respectively positioned on the upper and lower sides of the semiconductor substrate in the direction normal to the semiconductor substrate, and A semiconductor substrate inspection device using terahertz waves, wherein in the above tilted transmission mode, the emitter is positioned to be tilted from the normal direction of the semiconductor substrate on the upper side of the semiconductor substrate and is adjustable in tilting angle, and the detector is positioned on the lower side of the semiconductor substrate so as to correspond to the same line as the emitter with respect to the optical path.

9. In Paragraph 8, A semiconductor substrate inspection device using terahertz waves, wherein in the above tilted transmission mode, the emitter and detector scan while changing the optical path of the terahertz waves transmitting the internal defect.

10. In Paragraph 1, It further includes a first optical instrument and a second optical instrument, but, The first optical mechanism is provided between the emitter and the semiconductor substrate, and the second optical mechanism is provided between the semiconductor substrate and the detector. The terahertz waves generated from the emitter are irradiated onto the semiconductor substrate through the first optical device and then guided to the detector by the second optical device, A semiconductor substrate inspection device using terahertz waves, capable of rapid scanning of the entire surface area of ​​the semiconductor substrate by adjusting the angles of the first optical instrument and the second optical instrument.

11. In Paragraph 1, A semiconductor substrate inspection device using terahertz waves, capable of scanning the entire surface area of ​​the semiconductor substrate by moving and rotating the semiconductor substrate while the emitter and detector are fixed.

12. In Paragraph 1, A semiconductor substrate inspection device using terahertz waves, wherein the semiconductor substrate is any one of a group of substrate candidates including a silicon wafer, a glass substrate, and a plastic substrate.

13. In Paragraph 1, A semiconductor substrate inspection device using terahertz waves, wherein at least one emitter and a detector are provided, provided in a corresponding number.

14. A step of generating terahertz waves toward a semiconductor substrate; A step of detecting terahertz waves reflected from the semiconductor substrate or terahertz waves transmitted through the semiconductor substrate; and The method includes a step of inspecting a defect (crack) generated on the semiconductor substrate in real time based on the terahertz waves detected in the step of detecting the terahertz waves while the semiconductor process is in progress; A semiconductor substrate inspection method using terahertz waves, wherein the defects include surface defects of the semiconductor substrate and internal defects occurring in the thickness direction within the semiconductor substrate.

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