KR20100005754A - Apparatus for inspecting silicon structure utilizing beam splitter and method of inspecting silicon structure utilizing the same - Google Patents

Abstract

PURPOSE: An apparatus and a method for inspecting a silicon structure using a beam splitter are provided to safely and quickly inspect the inner or rear sides of the silicon structure without damaging the silicon structure. CONSTITUTION: An apparatus for inspecting a silicon structure comprises a light source(100), a beam splitter(200), a collimated light generator(300), and an optical detector(600). The light source projects laser beam. The beam splitter separates the laser beam projected by the light source. The collimated light generator receives the separated light beam and converts it into collimated light, and projects the collimated light to the whole surface of the silicon structure. The optical detector measures the power of the laser light passing through the silicone structure.

Description

Inspection device and inspection method of silicon structure using light splitter. {APPARATUS FOR INSPECTING SILICON STRUCTURE UTILIZING BEAM SPLITTER AND METHOD OF INSPECTING SILICON STRUCTURE UTILIZING THE SAME}

The present invention is to examine the state of the inside or the back of the silicon structure by irradiating the laser light to the silicon structure, the laser beam can be irradiated to the front surface of the silicon structure by a light splitter, thereby simply checking the state of the silicon structure. The present invention relates to an inspection apparatus and an inspection method for a silicon structure using an optical splitter.

Recently, as the demand for high performance and miniaturization of electronic products increases, various researches for increasing the degree of integration of semiconductor devices have been conducted. In particular, active researches on wafer stack manufacturing technology for vertically stacking a plurality of silicon wafers have been conducted. .

Wafer bonding technology is being used in many processes due to the increasing demand for handling wafer bonding in solar cell and image sensor processes to commercialize MEMS products and improve photon efficiency.

However, in the case of stacking a plurality of wafers as described above, an air gap may be generated between the bonding surfaces of the wafers due to incomplete bonding between the wafers, and also various processes for processing the wafers or manufacturing the wafer stacks may be performed. While scratches or cracks may occur on the back surface of the wafer.

However, such air gaps, scratches, or cracks may cause defects in the wafer stack or the semiconductor device. Therefore, a method capable of accurately inspecting the inside of the silicon wafer or the back surface of the wafer is required.

In the past, it was common to inspect the back or the inside of a silicon wafer using X-rays or sound waves.

However, the method of using the X-ray has a problem that the X-ray equipment is expensive and bulky, and in particular, a shielding chamber is required due to the characteristics of the X-ray harmful to the human body.

In addition, a method of using ultrasonic waves is a destruction test in which a measurement object is immersed in water, and, like X-ray equipment, sound wave generating equipment is expensive and bulky.

The present invention is to solve the above problems, an object of the present invention is to examine the state of the inside or the back of the silicon structure by irradiating the laser light on the silicon structure, the laser beam is a front splitter of the silicon structure by a light splitter It is possible to provide an inspection apparatus and an inspection method for a silicon structure using an optical splitter that can easily inspect the state of the silicon structure by allowing irradiation.

According to the present invention, in the inspection device for a silicon structure in the laser structure for inspecting the state of the silicon structure by irradiating the laser light to the silicon structure and measuring the power of the laser beam transmitted through the silicon structure according to the position, A light splitter for splitting the laser light output from the light source, a plurality of parallel light generators for receiving the split laser light, converting the split laser light into parallel light, and irradiating the front surface of the silicon structure; It is achieved by a photodetector that measures the power of the laser light that has passed through the structure.

The apparatus may further include a diffusion plate positioned between the parallel light generator and the silicon structure to diffuse the parallel light.

In addition, the parallel light generator may be a collimator.

In addition, the wavelength of the laser light may be 1.0μm to 1.3μm.

In addition, the method of inspecting the silicon structure by irradiating a laser beam to the silicon structure and measuring the power of the laser beam transmitted through the silicon structure according to the position, the inspection method of the silicon structure, (a) can pass through the silicon structure Preparing a laser beam; (b) dividing the laser beam using a light splitter; and (c) converting the divided laser beams into parallel lights by a plurality of parallel light generators; (d) irradiating the front surface of the silicon structure with the parallel light; (e) measuring the power of the laser light passing through the silicon structure according to a position; and (f) the power of the measured laser light. Comparing the size of may include.

In addition, after the step (c), (g) may further comprise the step of diffusing the parallel light using a diffusion plate.

In addition, the wavelength of the laser light may be 1.0μm to 1.3μm.

In addition, the steps (c), (d) and step (g) may be repeated, and in step (e), the average square root (RMS) value of the measured laser light power may be compared.

Thereby, by inspecting the state of the inside or the back of the silicon structure using a laser light of a wavelength that can penetrate the silicon structure, by allowing a laser beam to irradiate the front surface of the silicon structure by a light splitter, It is effective to grasp the state of the inside or the back of the silicon structure safely and quickly without destroying the structure.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention is to examine the state of the part that is not exposed to the outside, such as the inside of the silicon structure or the back of the silicon structure by irradiating the laser light, the laser beam is irradiated to the front surface of the silicon structure by a light splitter The power of the transmitted laser light is measured, and the magnitude of the measured power is compared for each location to grasp the structure inside the silicon structure.

Therefore, in the present invention, a laser beam capable of transmitting silicon is required. First, the silicon transmission characteristics of the laser beam will be described.

In this case, the silicon structure refers to various structures that can be manufactured using silicon, such as a silicon wafer, a silicon wafer stack, or various structures manufactured by MEMS technology.

FIG. 1 is a cross-sectional view of a silicon wafer 10 having a reflective layer 20 formed on a back surface 40, and illustrates a configuration for grasping silicon transmission characteristics of the laser light 70 according to a wavelength.

2 is a reflection spectrum of the laser light 70 measured by the configuration of FIG.

The reflection spectrum is obtained by measuring the power of the laser light 70 emitted from the light source 50 and transmitted through the silicon wafer 10 and reflected from the reflective layer 20 with the photodetector 60.

2 shows the reflection spectrum 80 when the front surface 30 of the silicon wafer 10 is polished smoothly and the reflection spectrum 90 when the scratch is formed on the front surface 30 of the silicon wafer 10. However, first, the silicon transmission characteristic of the laser beam 70 will be described using the reflection spectrum 80 when polished.

At this time, the front surface 30 of the silicon wafer 10 means a surface to which the laser light 70 is irradiated among the surfaces of the silicon wafer 10.

The laser light 70 irradiated onto the front surface 30 of the silicon wafer 10 is absorbed by the silicon wafer 10 in the course of passing through the inside of the silicon wafer 10.

In this case, the degree of absorption in the silicon wafer 10 varies depending on the wavelength of the laser light 70.

Therefore, when the power of the laser light 70 reflected and reflected from the reflective layer 20 formed on the back surface 40 of the silicon wafer 10 is measured according to the wavelength, the laser light that can penetrate the silicon wafer 10 ( 70) wavelength can be seen.

According to the reflection spectrum 80 in the case where the front surface 30 of the silicon wafer 10 is polished smoothly in FIG. 2, the laser light 70 transmits the silicon wafer 10 in the range of 0.3 μm to 1.3 μm. As can be seen, in the present invention, the laser beam 70 belonging to the wavelength range of 0.3 μm to 1.3 μm is used to determine the structure or state of the silicon structure.

In the case of the laser light 70 of 1.0 μm to 1.3 μm, since the laser light 70 of about 95% is returned, it can be seen that almost no absorption occurs in the silicon, and thus the light detector 60 having low light efficiency is used. Even if you have the advantage that can be used.

The thickness of the silicon wafer 10 used in the measurement of the reflection spectrum is about 300 μm, and silver (Ag) may be used as the material of the reflective layer 20.

3 is a schematic configuration diagram of a device for inspecting a silicon structure using a light splitter according to the present invention.

As shown in FIG. 3, the inspection apparatus for the silicon structure using the light splitter according to the present invention includes a light source 100, a light splitter 200, a plurality of parallel light generators 300, and a photodetector 600. .

The light source 100 generates the laser light 110 to be used in the inspection process of the silicon structure 500.

The laser light 110 emitted from the light source 100 is guided to the silicon structure 500 to be inspected by the light splitter 200 and the plurality of parallel light generators 300.

The laser light 110 irradiated to the silicon structure 500 is detected by the photodetector 600 after passing through the silicon structure 500.

When the laser light 110 irradiated to the silicon structure 500 encounters a structure made of air, metal, or glass in the process of passing through the inside of the silicon structure 500, air, metal, or The power is rapidly reduced because it is absorbed or reflected by a glass structure or the like.

Accordingly, when the power of the laser beam 110 passing through the silicon structure 500 is measured according to the position, the presence of the air gap and the location of the air gap can be known. The position of the structure of the metal or glass material included in the 500 may be determined, and as a result, it may be known whether the structures formed inside the silicon structure 500 are disposed in place.

However, while the diameter of the laser light 110 emitted from the light source 100 is generally several mm to several cm, the silicon structure 500 such as a silicon wafer has a diameter of 300 mm, the light splitter 200 and By using the plurality of parallel light generators 300 to allow the laser light 110 to irradiate the front surface of the silicon structure 500, the state of the silicon structure 500 may be determined regardless of the size of the silicon structure 500. To help.

The light splitter 200 divides the laser light 110 output from the light source 100, and receives the laser light 110 and divides the laser light 110 into a plurality of laser lights 110.

In addition, the collimator 300 is generally used as a collimator. The collimator is a device that makes the laser light 110 into parallel light with a very precise objective lens. It is formed in a number corresponding to the number, and converts the divided laser light 110 into parallel light to irradiate the entire front surface 520 of the silicon structure 500.

For example, since the diameter of the laser light 110 output from the light source 100 is generally several mm to several cm, the silicon structure 500 such as a silicon wafer has a diameter of 300 mm, so that the silicon structure 500 It is difficult to examine the entirety of the front surface 520.

Therefore, the laser light 110 output from the light source 100 is divided into a plurality of light splitters 200 so as to irradiate the entire front surface 520 of the silicon structure 500, and the parallel light generator 300. Forming a plurality of the laser beam 110 is divided into a plurality of parallel light respectively to be irradiated to the entire surface 520 of the silicon structure 500.

Here, the front surface 520 of the silicon structure 500 refers to a surface to which the laser light 110 of the surface of the silicon structure 500 is irradiated. Reference numeral 510 denotes a rear surface which is a surface opposite to the front surface 520 of the silicon structure 500.

In this case, the laser light 110 output from the light source 100 is input to the light splitter 200, and the plurality of laser lights 110 divided by the light splitter 200 are input to the plurality of parallel light generators 300. The input is preferably input by an optical fiber.

On the other hand, the photodetector 600 is for measuring the power of the laser light 110 transmitted through the silicon structure 500, a CCD camera or a power meter (power meter) may be used.

The power of the laser light 110 measured by the photodetector 600 is preferably stored in a memory means or the like corresponding to the coordinates of the region to which the laser light 110 is irradiated.

In this case, the state of the silicon structure 500 may be determined by the mean square root (RMS) value of the measured power.

In addition, the inspection apparatus of the silicon structure using the light splitter according to the present invention may further include a diffusion plate 400 for diffusing the parallel light converted by the parallel light generator 300.

The diffusion plate 400 is disposed between the parallel light generator 300 and the silicon structure 500, which diffuses the parallel light to irradiate the entire front surface 520 of the silicon structure 500.

For example, when the diffusion plate 400 is not formed, in order to irradiate the entire front surface 520 of the silicon structure 500 with the laser light 110, it corresponds to the entire area of the front surface 520 of the silicon structure 500. The parallel light generator 300 must be formed.

In this case, since the number of parallel light generators 300 increases, a problem arises in that the cost increases and the installation area increases.

However, when the diffusion plate 400 is formed between the parallel light generator 300 and the silicon structure 500, since the parallel light may be diffused to irradiate a larger area, the number of the parallel light generators 300 may be increased. Is reduced, thereby reducing the cost and reducing the installation area.

Hereinafter, the inspection process of the silicon structure inspection apparatus using the light splitter according to the present invention will be described in more detail.

4 is a cross-sectional view of a silicon wafer stack 700 with an air gap 720 formed therein.

The air gap 720 is generated when the bonding between the stacked wafers 710 is incomplete.

The laser light 110 generated by the light source 100 is irradiated onto the front surface 730 of the silicon wafer stack 700 via the light splitter 200, the parallel light generator 300, and the diffusion plate 400. After passing through the stack 700, it is detected by the photodetector 600.

At this time, when the laser light 110 passes through the portion where the air gap 720 is formed, a part of the laser light 110 is reflected by the air gap 720 or absorbed in the air gap 720.

Therefore, the power of the laser light 110 passing through the air gap 720 has a value smaller than the power of the laser light 110 passing through the portion where the air gap 720 does not exist.

Therefore, it can be seen that the air gap 720 is present in the portion corresponding to the position where the power of the laser light 110 is measured relatively small.

FIG. 5 is a cross-sectional view of a silicon wafer 710 having a scratch 760 formed on a rear surface 750, and illustrates a case where a scratch 760 having a triangular cross section is formed.

In this case, the rear surface 750 refers to a surface opposite to the front surface 740 to which the laser light 110 is irradiated.

1 and 2 to describe the transmission characteristics of the laser light 110 when the scratch 760 is formed on the back surface 750 of the silicon wafer 710, the silicon wafer with the front surface 30 smoothly polished. When the laser light 70 is irradiated to the wavelength 10 with a wavelength of 1.0 μm or more, about 95% of the laser light 70 is transmitted, whereas about 60% of the scratches are formed on the front surface 30 of the silicon wafer 10. It can be seen that only the reflection comes out.

The reduction of the reflected laser light 70 may be explained as total reflection generated at the contact surface of the front surface 30 of the silicon wafer 10 with air.

That is, when the inclination occurs on the front surface 30 of the silicon wafer 10 by scratching, the laser light 70 reflected from the reflective layer 20 is totally reflected on the front surface 30 of the silicon wafer 10, and the reflective layer 20 is again reflected. Because it proceeds toward).

Accordingly, as a result of irradiating the laser light 110 having a wavelength of 1.0 μm to 1.3 μm using the silicon structure inspection apparatus of FIG. 3, on the silicon wafer 710 having the scratch 760 formed on the rear surface 750 as shown in FIG. 5. If an area where the power of the laser light 110 is reduced by about 35% is found, it can be seen that the scratch 760 is present on the back surface 750 of the silicon wafer 710 corresponding to the area.

However, according to the reflection spectrum of FIG. 2, when the wavelength of the laser light 70 is 0.3 μm to 1.2 μm, it can be seen that the reflectance is reduced by about 5 to 10% by scratch. The laser having the wavelength of 0.3 μm to 1.2 μm Of course, the light 110 may be used.

6 is a cross-sectional view of a silicon structure 800 fabricated by MEMS technology.

The silicon structure of FIG. 6 includes a body including an upper surface 810 and a lower surface 820, a left surface 830 and a right surface 840, and an internal structure 850 included in the body.

The internal structure 850 may be formed of a material such as silicon or glass coated with metal.

When the laser light 110 is irradiated through the upper surface 810 of the silicon structure 800 having the structure of FIG. 6, the power of the laser light 110 passing through the internal structure 850 causes the internal structure 850. As shown in FIG. 6, the position of the internal structure 850 that is not exposed to the outside may be easily determined by having a value smaller than that of the laser light 110 that does not pass.

FIG. 7 is a plan view of a silicon wafer 710 on which alignment markers 770 are formed, and FIG. 8 illustrates a stacking state of two silicon wafers 710 on which alignment markers 770 are formed using the silicon structure inspection apparatus of the present invention. A conceptual diagram showing the process of grasping.

An alignment marker 770 made of a metal material is formed on the silicon wafer 710 so as to confirm the alignment state in the process of stacking the wafers.

When the silicon wafers 710 are ideally stacked, the positions of the alignment markers 770 formed on the silicon wafers 710 coincide with each other.

The laser light 110 is reduced in the course of passing through the alignment marker 770, the silicon wafer 710 is measured by comparing the power of the laser light 110 passed through the stacked silicon wafer 710 according to the position ), You can see the alignment status.

That is, the power of the laser light 110 that has passed through the alignment markers 770 formed on the two silicon wafers 710 is only the alignment marker 770 formed on the silicon wafer 710. In comparison, the power loss is approximately twice that of the laser. The power loss of the laser light 110 that passes through the silicon wafer 710 can be measured to accurately determine the alignment of the silicon wafer 710.

The embodiments and drawings attached to this specification are merely to clearly show some of the technical ideas included in the present invention, and those skilled in the art can easily infer within the scope of the technical ideas included in the specification and drawings of the present invention. It is apparent that all modifications and specific embodiments that can be included in the scope of the technical idea of the present invention.

1 is a cross-sectional view of a silicon wafer with a reflective layer formed on its back surface.

2 is a reflection spectrum measured by the configuration of FIG. 1.

3 is a block diagram of a silicon structure inspection apparatus using a light splitter according to the present invention.

4 is a cross-sectional view of a silicon wafer stack with an air gap formed thereon.

5 is a cross-sectional view of a silicon wafer with a scratch formed on its back surface.

6 is a cross-sectional view of a silicon structure made by MEMS technology.

7 is a plan view of a silicon wafer with alignment markers formed thereon.

8 is a conceptual diagram illustrating a process of determining a stacking state of a silicon wafer.

<Description of the symbols for the main parts of the drawings>

 10 silicon wafer 20 reflective layer

 30: front 40: rear

 50: light source 60: photodetector

 70: laser light 80: reflection spectrum when polished

 90: reflection spectrum when scratch is formed

100: light source 110: laser light

200: light splitter 300: parallel light generator

400 diffusion plate 500 silicon structure

600: photodetector 700: silicon wafer stack

710 silicon wafer 720 air gap

730: front 740: front

750: rear 760: scratch

770: alignment marker 800: silicon structure

810: upper surface 820: lower surface

830: sin side 840: right side

850: Internal structure

Claims (8)

An inspection apparatus for a silicon structure in which a laser beam is irradiated to a silicon structure and the power of the laser beam transmitted through the silicon structure is measured according to a position to inspect the state of the silicon structure. A light source for outputting laser light; A light splitter for dividing the laser light output from the light source; A plurality of parallel light generators which receive each divided laser light and convert the split laser light into parallel light and irradiate the front surface of the silicon structure; And a photodetector configured to measure the power of the laser beam passing through the silicon structure. The method of claim 1, And a diffusion plate positioned between the parallel light generator and the silicon structure to diffuse each of the parallel light beams. The method of claim 1, And the parallel light generator is a collimator. The method of claim 1, The wavelength of the laser light is a silicon structure inspection device using a splitter, characterized in that 1.0μm to 1.3μm. In the silicon structure inspection method of irradiating a laser beam to the silicon structure and measuring the power of the laser beam transmitted through the silicon structure according to the position to inspect the state of the silicon structure, (a) preparing a laser beam that can penetrate the silicon structure; (b) dividing the laser light using a light splitter; (c) a plurality of parallel light generators receiving each of the divided laser beams and converting the divided laser beams into parallel light beams; (d) irradiating the front surface of the silicon structure with the parallel light; (e) measuring, according to position, the power of the laser light that has passed through the silicon structure; (f) comparing the magnitudes of the measured powers of the laser beams. The method of claim 5, After the step (c), (g) diffusing the parallel light by using a diffusion plate. The method of claim 5, The wavelength of the laser light is 1.0μm to 1.3μm silicon structure inspection method using a splitter, characterized in that. The method according to any one of claims 5 to 7, Repeat step (c), step (d) and step (g), and in step (e) using the optical splitter, characterized in that comparing the average square root (RMS) value of the measured laser light power How to inspect silicon structures.

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