KR20110017679A - Device and method for measuring height between top and bottom of sample - Google Patents

Abstract

PURPOSE: A device for measuring the height between top and bottom of samples is provided to a accurately detect the height difference value regardless the surface condition of measurement samples. CONSTITUTION: A device for measuring the height between top and bottom of samples comprises a lighting light, a first imaging unit, a second imaging unit, an analyzing device(120), and a controller. A pattern plate is located in front of a light source(20) and produces a pattern beam. The first imaging unit images the pattern beam illuminated from the lighting light in a measurement sample(40).

Description

Device and method for measuring height between top and bottom of sample}

The present invention relates to a height difference measuring apparatus and a method, and more particularly, to a height difference measuring apparatus and method for improving the measurement accuracy and reproducibility of the height difference value of the measurement sample by using the pattern beam as the illumination light.

Recently, with the miniaturization of electronic products, in order to increase the degree of integration of components on a PCB substrate, a ball grid array (BGA) type package in which balls are arranged in a grid form instead of a conventional lead is being used. Since the BGA cannot be visually inspected once it is mounted on the PCB, quality inspection such as ball position and size height inspection is essential in advance.

In particular, the coplanarity that the height of the ball is uniform so that the vertices of the ball must be in one plane is very important. This is because, if the height of the ball is not uniform, the balls with low ball height are very likely to be in poor contact.

However, since the general two-dimensional image inspection can measure only the size of the ball seen from the ball, three-dimensional measurement technology is required to measure the exact height of the ball. In addition, non-contact three-dimensional measurement technology without damage to the ball among the three-dimensional measurement technology is required.

Non-contact three-dimensional measurement techniques include laser scan, confocal method, white light interference method, phase shift interference method, and extended focus method. The laser scanning method uses trigonometry as a measuring principle. Despite the fact that the accurate center extraction of the laser is the core technology, the repeatability and accuracy of the extraction is not guaranteed in the actual inspection environment.

In the case of the confocal method, the laser beam is scanned with high precision, but the inspection speed is low, so only a part of it is applied to the 3D inspection market.

The white light interference method and the phase shift interference method have high precision but are extremely sensitive to the measurement environment. Therefore, the expensive anti-vibration structure and vibration desensitization algorithm are the key technologies when applied to the actual tester. The extended focus method uses a microscope to move the objective lens down or up at a certain interval, and then finds three-dimensional shapes by finding only the focused part of the image taken at each height by software. Is low.

As described above, the measurement of the three-dimensional shape of the measurement sample by the non-contact three-dimensional shape measuring device is also important, but in the case of the BGA-shaped package among the measurement objects, the difference between the top position of the ball and the height value of the PCB bottom surface may be an important value. .

Accordingly, the present invention provides an apparatus for detecting a difference between the highest height value and the lowest height value of a measurement object. The height difference measuring apparatus according to the present invention can increase the measurement accuracy and reproducibility of the height difference value of the measurement sample by using the pattern beam as the illumination light.

Accordingly, the technical problem to be achieved by the present invention relates to a height difference measuring apparatus and method for improving the measurement accuracy and reproducibility of the height difference value of the measurement sample by using the pattern beam as the illumination light.

The present invention provides a height difference measuring device devised to achieve the above object, a light source for outputting white light; A plate having a lattice pattern illuminated by the light source; A first imaging lens for forming the grating pattern at infinity; A beam-splitter for transmitting the light transmitted through the imaging lens to a measurement sample; An objective lens for imaging the light reflected by the beam splitter on the grating pattern on the measurement sample surface; A second imaging lens for imaging the light transmitted through the beam-splitter by imaging the measurement sample surface illuminated by the grid pattern formed by the objective lens with the objective lens; A CCD for recording an image formed by the second imaging lens; A whole measuring system including the light source, the grating pattern plate, the first imaging lens, the beam splitter, the objective lens, the second imaging lens, and the CCD; A control unit for moving the measurement unit; And an analysis apparatus including an automatic focusing function for analyzing the image recorded in the CCD and moving the measurement unit to a height value of a top surface of the measurement sample or a focused position of a bottom surface of the measurement sample. Characterized in that it comprises a.

According to still another feature of the present invention, the control unit includes a controller and a translator, and moves to the highest position predetermined in the translator in order to measure the height of the uppermost surface of the measurement sample. After finding the exact position of the high side, after finding the exact position, it moves to the lowest position predetermined in the translator, and then finds the height value of the bottom surface of the measurement sample.

In addition, the height difference measuring method of the height difference measuring apparatus according to the present invention devised to achieve the above object, the step of moving to the highest position predetermined in advance; Illuminating the grating pattern beam on the measurement specimen; Passing the illuminated grating pattern through a first imaging lens and optically imaging the measurement sample through the measuring unit; The grating pattern formed on the measurement sample acts as illumination light on the measurement sample to form an image of the surface where the pattern and the measurement sample are combined with the objective lens and the second imaging lens; Recording an image passing through the objective lens and the second imaging lens on a CCD; Analyzing the image recorded in the CCD to find a height value of the uppermost surface of the measurement sample; And after finding the height value of the uppermost surface, moving the measurement unit to the lowest predetermined position, and then finding the position of the bottom surface of the measurement sample.

According to another feature of the present invention, before the step of finding the highest surface and the bottom surface of the measurement sample, it characterized in that it comprises the step of pre-determining the position values of the highest point and the lowest point of the translator.

According to the present invention, the measurement accuracy and reproducibility of the height difference value of the measurement sample are improved by using the pattern beam as the illumination light.

In addition, according to the present invention, by illuminating the pattern beam, it is possible to accurately find the height difference value between the top and bottom surfaces of the measurement sample, regardless of the surface state of the top and bottom surfaces of the measurement sample, the height of the measurement sample Measurement accuracy and reproducibility of difference values are improved.

Hereinafter, with reference to the accompanying drawings in accordance with a preferred embodiment of the present invention will be described.

1 is a configuration diagram schematically illustrating a configuration of an apparatus for measuring height difference according to an embodiment of the present invention.

The height difference measuring apparatus in FIG. 1 is largely comprised from an illumination part, a 1st imaging part, a 2nd imaging part, a conveyance part, the analyzer 120, etc. In FIG.

The lighting unit is a portion that illuminates the pattern beam on the measurement sample, and includes a light source 20 and a pattern unit 10. That is, in order to raise the pattern beam to the measurement sample 40, the pattern portion 10 is placed in front of the light source 20 to illuminate the light.

The light source 20 uses white light or LED.

The pattern portion 10 includes a pattern to form the measurement sample 40, and is positioned in front of the light source 20 to emit the pattern beam. The pattern of the pattern portion 10 may be a grid pattern. That is, the pattern portion 10 may be formed of a plate having a lattice pattern.

The first imaging unit is a part for forming a pattern beam illuminated from the light source 20 and the pattern unit 10 on a measurement sample. The first imaging unit includes a first imaging lens 80, a beam splitter 60, and an objective lens 50. . That is, two lenses, that is, the first imaging lens 80 and the objective lens 50, were used to image the pattern beam by the pattern portion 10 to the measurement sample 40 at the imaging portion.

The first imaging lens 80 arranges the pattern portion 10 at the focal length so that the beam emitted from the light source 20 through the pattern portion 10 is formed at infinity.

The beam splitter 60 reflects the light passing through the first imaging lens 80 to be directed toward the objective lens 50.

The objective lens 50 is an objective lens used for a general microscope, and the pattern beam incident through the beam splitter 60 makes the pattern (lattice pattern) of the pattern portion 10 at the focal point of the objective lens 50. do.

The second imaging unit is a portion that causes the CCD 30 to reflect the beam reflected from the measurement sample 40. The objective lens 50, the beam splitter 60, the second imaging lens 70, and the CCD 30 And so on.

The objective lens 50 causes the beam reflected from the measurement sample 40 to be raised to infinity.

The beam splitter 60 directs the beam passing through the objective lens 50 toward the second imaging lens 70.

The second imaging lens 70 images the pattern beam incident through the beam splitter 60 on the CCD 30.

The CCD 30 detects an image of the pattern beam incident through the second imaging lens 70 and transmits the image to the analyzer 120. That is, the CCD 30 records an image formed by the second imaging lens 70.

The transfer unit (control unit) is a means for automatically adjusting the position of the measuring unit 130 in accordance with the position control signal of the analysis device 120, that is, a means for moving the position of the measurement sample 40 relatively, The translator 100 and the controller 110 are provided.

The controller 110 drives the translator 100 to move the position of the measurement unit 200 to the next position for focusing the image formed by the CCD 30 by analyzing the focusing degree with the analyzer 120. .

The translator 100 is driven by the controller 110 to adjust the position of the measuring unit 130.

That is, the transfer unit (control unit) is composed of a controller and a translator, in order to measure the height of the uppermost surface of the measurement sample, after moving the measuring unit 130 to the highest position predetermined in the translator, the measurement After finding the exact position of the highest surface of the sample, after finding the exact position, the measurement unit 130 is moved to the lowest position predetermined in the translator, and then the height value of the bottom surface of the measurement sample is found.

The analyzer 120 analyzes the image input from the CCD 30, generates a position control signal of the measurement unit 130, and transmits the generated control signal to the controller 110. The analyzing apparatus 120 includes software for numerically analyzing the recorded pattern image. That is, the analysis device 120 includes software for analyzing the image recorded in the CCD and moving the measurement unit 130 to the height value of the top surface of the measurement sample or the focused position of the bottom surface of the measurement sample. Auto focus is included.

In other words, the pattern portion 10 is placed in front of the light source 1 to illuminate the light in order to raise the pattern beam to the measurement sample 40. Two lenses were used to bring the pattern to the sample 40. Of the two lenses, the objective lens 50 is an objective lens used in a general microscope, and the pattern portion 10 is placed at the focal length of the first imaging lens 80 to raise the beam emitted from the light source 20 to infinity. The light passing through the first imaging lens 80 is reflected by the beam splitter 60 to be directed toward the objective lens 50. The beam directed to the objective lens 50 forms a pattern at the focal point of the objective lens 50. The measurement sample 40 including the pattern is brought to infinity with the objective lens 50. The beam passing through the objective lens 50 passes through the beam splitter 60 and is imaged on the CCD 30 by the second imaging lens 70.

2 is a schematic explanatory diagram of a height difference measuring method according to an exemplary embodiment of the present invention. That is, Figure 2 shows an algorithm designed to find the difference between the highest height value and the lowest height value of the measurement sample 40 in the height difference measuring apparatus according to the present invention.

The transfer unit (control unit), which is a device for moving the measuring unit 130, includes a translator 100, a controller 110 that controls the translator 100, and a software for analyzing an image formed on the CCD 30. It is comprised by the computer which is the analysis apparatus 120. The analyzer 100 moves the translator 100 using the controller 110 so as to analyze the image formed on the CCD 30 and automatically focus to the highest position and the lowest position of the sample.

In the movement of the highest position, the camera is moved to the highest position by moving the measurement unit 130 to the position of the highest measurement unit (S10). This is the basic preparation for performing focusing (auto focusing) while moving from top to bottom.

That is, the objective lens 50 is forcibly moved to a position higher than the position of the objective lens 50 for forming the image at the highest position of the measurement sample 40 in order to find the highest position value. The best position where the objective lens 50 is forcibly moved will be referred to as the highest measurement position. The position of the uppermost measurement unit is determined so as to find the highest position of the measurement sample 40 most quickly according to the measurement sample 40 at a predetermined value. The position of the highest measurement unit corresponds to an initial value for automatically finding the highest position of the measurement sample 40.

In the search for the highest position of the measurement sample, focusing is performed while gradually moving down from the highest position (S20), and the highest position of the measurement sample 40 is found and recorded (S30). In other words, while moving the measuring unit from the position of the uppermost measuring unit to the automatic focus to the highest position of the measurement sample 40.

In the lowest position moving step, the camera is moved to the lowest position by moving the measuring unit 130 to the lowest measuring unit position (S40).

That is, after finding the highest position of the measurement sample 40 in the uppermost position search step of the measurement sample, the measurement unit 130 is lower than the position of the objective lens 50 to form the lowest position of the measurement sample 40. Force the measurement unit 130 to the position. The lowest position where the measuring unit 130 is forcibly moved will be referred to as the lowest measuring unit position. The position of the lowest measurement part is determined so as to find the lowest position of the measurement sample 40 most quickly according to the measurement sample 40 at a predetermined value.

In the search for the lowest position of the measurement sample, focusing is performed while gradually moving upward from the lowest position (S50), and the lowest position of the measurement sample 40 is found and recorded (S60). That is, the position of the lowest measurement unit corresponds to an initial value for automatically finding the lowest position of the measurement sample 40, and to automatically focus to the lowest position of the measurement sample 40 while moving the objective lens upward. In this way, the difference between the height value of the highest position and the lowest position of the measurement sample 40 is found.

In the height difference calculation step, the difference between the height value of the highest position and the lowest position of the obtained measurement sample 40 is calculated (S70).

In other words, the height difference measuring method includes the steps of moving the measuring unit 130 to a predetermined highest position; Illuminating the grating pattern beam on the measurement specimen; Passing the illuminated grating pattern through a first imaging lens and optically imaging the measurement sample through the objective lens; The grating pattern formed on the measurement sample acts as illumination light on the measurement sample to form an image of the surface where the pattern and the measurement sample are combined with the objective lens and the second imaging lens; Recording an image passing through the objective lens and the second imaging lens on a CCD; Analyzing the image recorded in the CCD to find a height value of the uppermost surface of the measurement sample; After the height value of the top surface is found in the control unit, the step of moving the measuring unit 130 to the lowest position in which the translator is predetermined, and then finding the position of the bottom surface of the measurement sample. In addition, prior to the step of finding the highest surface and the bottom surface of the measurement sample, it may include the step of pre-determining the position values of the highest point and the lowest point of the translator.

3 is an embodiment of the present invention when the measurement object is a ball grid array (BGA) when the pattern beam is irradiated by the CCD (a) the image focused on the top position of the BGA ball (b) on the PCB bottom surface This picture shows the focused image.

That is, Figure 3 is a case where the BGA is attached to the substrate as an example of the measurement sample 40 in the height difference measuring apparatus according to the present invention, Figure 3 (a) is a view of the ball at the highest height of the measurement sample 40 The image is imaged on the CCD 30 after illuminating the peak and the pattern beam at the highest point. 3B is an image formed on the CCD 30 after illuminating the substrate surface at the lowest height of the measurement sample 40 and the pattern beam on the substrate surface. In other words, when the measurement sample is the BGA measurement results of Figure 3 is shown in Table 1 the height difference measurement results.

<Table 1. Height Difference Measurement Result when BGA is BGA>

4 is a view illustrating a result measured by the height difference measuring apparatus of the present invention when the measurement object is a BGA according to one embodiment of the present invention.

4 shows that the algorithm for finding the highest and lowest height of the sample when the sample is BGA focuses the image of the lowest position of the sample on the CCD 30 and then upwards by 1 μm. The image obtained by the CCD 30 while moving the objective lens is inputted to the software used in the analysis device 110 of the height difference measuring device of the present invention, and the analysis result is shown.

In FIG. 4, the x-axis value is a height value and the y-axis value is a value indicating the degree of focus, and the higher the value, the better the focus on the surface. In FIG. 4, it can be seen that there are three positions having the maximum value of the derivative value 0. The maximum value that appears on the left side is when the bottom surface of the BGA, the measurement sample 40, is focused, and the maximum value that appears on the right side is The top surface of the BGA ball, which is the measurement sample 40, is focused.

As a feature of the height difference measuring device of the present invention, the pattern beam is irradiated, and the conditions of the measurement sample 40 are changed in order to find out the accuracy of finding the height difference value which is the usefulness of the pattern beam.

5 is an embodiment of the present invention, when the measurement object is a BGA and the bottom surface does not have a mirror-like pattern, when the image is irradiated with normal light (a) the image focused on the highest position of the BGA ball, ( b) an image focused on the bottom surface without a pattern, (c) an image focused on the topmost position of a BGA ball photographed by a CCD when irradiated with a pattern beam, and (d) an image focused on the bottom surface without a pattern. to be.

FIG. 5 shows a sample (Sample A) having the bottom surface mirrored by placing a ball used for BGA on a glass plate.

5 (a) and 5 (b) show images of the top and bottom surfaces of Sample A focused on the CCD 4 by irradiating a general light source instead of the pattern beam. 5 (c) and 5 (d) show images of the top and bottom surfaces of Sample A focused on the CCD 4 using the height difference measuring apparatus of the present invention.

Since the beam used as the illumination light in the height difference measuring apparatus of the present invention is a pattern beam, it can be seen that the pattern is focused on the top and bottom surfaces of the sample A in FIGS. 5C and 5D.

Figure 6 is an embodiment of the present invention when the measurement object is a BGA and when the bottom surface is irradiated with normal light without a pattern when there is no pattern such as a mirror (a) measured result, the height difference measurement of the present invention (B) shows the measured result when the pattern beam is irradiated with the device.

 That is, when the pattern beam is irradiated on the sample A and when the normal light is irradiated, the image is input to the software used in the algorithm for finding the height difference by the height difference measuring apparatus of the present invention, and the value is found. Shown in

FIG. 6A is a result when it is irradiated with normal light, and FIG. 6B is a result when it is irradiated with the pattern beam used by the height difference measuring apparatus of this invention. In FIG. 6, the x-axis value is a height value, and the y-axis value is a value indicating the degree of focus, and the higher the value, the better the focus is on the surface. As shown in FIG. 6A, it can be seen that it is difficult to find the height value of the bottom surface of the sample A when the general light is irradiated. In contrast, Figure 6 (b) it can be seen that the bottom surface and the highest position value of the sample A accurately found. The above is summarized in Table 2.

<Table 2. Measurement result of height difference of sample A when used illumination light is normal light and pattern beam>

The results in Table 2 show that similar measurements were obtained in both cases. However, this result is obtained by analyzing the images taken while increasing the height of the objective by 1 μm. The result may be different when the actual autofocus function is used.

In the case of illumination using general light in a height measuring device having an autofocus function, as shown in Fig. 6a, the area of the focused image portion of the bottom surface may be too narrow, so there is a high possibility of missing the value of the bottom portion. On the other hand, when the pattern beam is used as the illumination used in the height measuring device of the present invention, as shown in (b) of FIG. 6, it can be seen that the height difference value can be found accurately regardless of the state of the bottom surface of the measured sample. Can be.

In another embodiment of the present invention, when the bottom surface of the measurement sample 40 is constant, the lowest and lowest position values of the measurement sample 40 are found only once, and only the highest and highest position values thereafter are measured. It can increase.

FIG. 7 is an explanatory diagram of a method of finding only the highest position while moving the entire area of the measurement object after measuring the height of the bottom surface once when the height of the bottom surface of the measurement object is constant according to an embodiment of the present invention. .

In FIG. 7, the transfer unit, which is a device for moving the measurement unit 130, includes an analysis device including a translator 10, a controller 110 controlling the translator 10, and software for analyzing an image formed on the CCD 30. It consists of a computer which is 120. The analyzer 130 moves the measurement unit 130 by using the controller 110 to analyze the image formed on the CCD 30 and to automatically focus to the highest position and the lowest position of the sample.

In the lowest position moving step, the objective lens 30 is relatively moved to the lowest position by moving the measuring unit 130 to the lowest measuring unit position (S110). This is the basic preparation for performing focusing (auto focusing) while moving from the bottom up.

That is, forcibly moving the measuring unit 130 to a position lower than the position of the objective lens 50 for forming the measuring unit 130 at the lowest position of the measuring sample 40 to find the lowest position of the measuring sample 40. Let's do it. The lowest position where the measuring unit 130 is forcibly moved will be referred to as the lowest measuring unit position. The position of the lowest measurement part is determined so as to find the lowest position of the measurement sample 40 most quickly according to the measurement sample 40 at a predetermined value.

In the search for the lowest position of the measurement sample, focusing is performed while gradually moving upward from the lowest position (S120), and the lowest position of the measurement sample 40 is found and recorded (S130). That is, the position of the lowest measurement unit corresponds to an initial value for automatically finding the lowest position of the measurement sample 40, and to automatically focus to the lowest position of the measurement sample 40 while moving the objective lens upward.

In the movement of the highest position, by moving the measuring unit 130 to the position of the highest measuring unit, the objective lens is moved to a relatively highest position (S140).

That is, forcing the measurement unit 130 to a position higher than the position of the objective lens 50 for forming an image at the highest position of the measurement sample 40 to find the lowest position value of the measurement sample 40 and then finding the highest position. Move it. The best position where the measuring unit 130 is forcibly moved will be referred to as the highest measuring unit position. The position of the uppermost measurement unit is determined so as to find the highest position of the measurement sample 40 most quickly according to the measurement sample 40 at a predetermined value.

In the search for the highest position of the measurement sample, focusing is performed while gradually moving down from the highest position (S150), and the uppermost position of the measurement sample 40 is found and recorded (S160). That is, the position of the highest measurement unit corresponds to an initial value for automatically finding the highest position of the measurement sample 40, and automatically moves to the highest position of the measurement sample 40 while moving the measurement unit 130 downward. Be sure to In this way, the difference between the height value of the highest position and the lowest position of the measurement sample 40 is found.

In the height difference calculation step, the difference between the height value of the highest position and the lowest position of the obtained measurement sample 40 is calculated (S170).

In this way, the height difference value between the highest position and the lowest position of the measurement sample 40 is obtained, and then the horizontal movement of the measurement sample 40 is performed to find the height difference value at another position of the measurement sample 40. In order to find the height difference value between the highest position and the lowest position at another position of 40), the measurement unit 130 is forcibly moved to the position of the highest measurement unit. By repeatedly measuring in the above-described method, it is possible to find the height difference value of all parts of the measurement sample 40.

In another embodiment of the present height difference measuring apparatus, several parts of the same pattern may be simultaneously measured in order to find a height difference value of the measurement sample 40 in which the same pattern is repeated, such as BGA.

8 is a diagram of a measurement object in which a certain pattern is repeated.

An example of a measurement sample 40 in which the same pattern is repeated is shown in FIG. 8. 8 includes the structures 200, 201, 202, and 203 that appear repeatedly among the measurement objects. In Fig. 8, the curved part shows an abbreviation for the repeated part. In FIG. 8, the circle is a structure having a height and is a height difference measurement object.

The area for imaging the measurement sample 40 with the same pattern repeated on the CCD 30 with the objective lens 50 is limited. For example, only the inside of the rectangular area formed by the dotted lines of FIG. It can be assumed that it can form an image.

FIG. 9 is a view illustrating dividing an area by dividing an image photographed by a CCD into only a portion of the measurement object in FIG. 8.

That is, FIG. 9 shows a picture obtained by dividing an image formed on an objective lens into four equal parts. Here, each of the quartered regions is referred to as a region, b region, c region, and d region.

As shown in FIG. 9, in order to find a height difference value in each quadrant region, only the structure 102 is formed in each region of the quadrant in the image photographed by the objective lens 50. The objective lens 50 is selected so that the images of the remaining structures do not overlap. The objective lens 50 is selected so that the remaining areas do not overlap each other.

FIG. 10 is a diagram illustrating an algorithm for extending a measurement area of a measurement object according to an embodiment of the present disclosure.

That is, FIG. 10 shows an algorithm designed to find the difference between the highest high position and the lowest low position in the measurement sample 40 in which the same pattern is repeated in the height difference measuring apparatus according to the present invention.

In FIG. 10, the transfer unit, which is a device for moving the measuring unit 130, includes an analysis device including a translator 10, a controller 110 controlling the translator 10, and software for analyzing an image formed on the CCD 30. It consists of a computer which is 120. The analysis device 120 analyzes the image formed on the CCD 30 to find the highest position and the lowest position of the sample.

In the lowest position moving step, by moving the measuring unit 130 to the lowest measuring unit position, the objective lens is relatively moved to the lowest position (S210).

In the search for the lowest and highest positions, focusing is performed while gradually moving upward from the lowest position, and the lowest and highest positions of the measurement sample 40 are found and recorded (S220). When the lens is in the highest position, search for the lowest and highest positions of the measurement sample 40 is terminated (S230).

In the height difference calculation step, the difference between the height value of the highest position and the lowest position of the obtained measurement sample 40 is calculated (S240).

In a different position moving step, after checking whether all the measurement areas have been searched, and if all the measurement areas have been found, if not all the measurement areas are found, after moving to the next measurement area, the process returns to the lowest position moving step (S250). .

That is, as shown in FIG. 10, the measurement unit 130 is forcibly moved to the position of the lowest measurement unit in order to simultaneously find the difference between the highest position and the lowest height value of several places in the measurement sample 40 in which the same pattern is repeated. It moves from the lowest objective lens position to a constant height, for example 1 μm, while moving the image from each position to the highest measurement position. In the constant height image thus obtained, each area of the quadrant is divided to find a height difference value in each area. After the height difference value is found, the measurement unit 130 is moved to another region of the measurement sample 40 and the difference between the height value of the highest position and the lowest position of the measurement sample 40 is found in the same manner.

 The translator can move the position of any of the sample, the CCD, and the objective lens. The present invention is not limited to the embodiment, but only to move the measurement sample as an example thereof, of course, more modifications and variations are possible to those skilled in the art within the scope of the following claims.

1 is a view showing the configuration of the height difference measuring apparatus according to an embodiment of the present invention.

2 is a view showing an algorithm for the height difference measuring apparatus method of the present invention.

FIG. 3 is a view illustrating an image focused on a top position of a BGA ball photographed by a CCD when a pattern beam is irradiated when a measurement object is a BGA according to an embodiment of the present invention. It is a photograph.

4 is a view illustrating a result measured by the height difference measuring apparatus of the present invention when the measurement object is a BGA according to one embodiment of the present invention.

5 is an embodiment of the present invention, when the measurement object is a BGA and the bottom surface does not have a mirror-like pattern, when the image is irradiated with normal light (a) the image focused on the highest position of the BGA ball, ( b) an image focused on the bottom surface without a pattern, (c) an image focused on the topmost position of a BGA ball photographed by a CCD when irradiated with a pattern beam, and (d) an image focused on the bottom surface without a pattern. to be.

Figure 6 is an embodiment of the present invention when the measurement object is a BGA and when the bottom surface is irradiated with normal light without a pattern when there is no pattern such as a mirror (a) measured result, the height difference measurement of the present invention (B) shows the measured result when the pattern beam is irradiated with the device.

FIG. 7 is an explanatory diagram for a method of finding only the highest position while moving the entire area of the measurement object after measuring the height of the bottom surface once when the height of the bottom surface of the measurement object is constant according to an embodiment of the present invention.

8 is a diagram of a measurement object in which a certain pattern is repeated.

FIG. 9 is a view illustrating dividing an area by dividing an image taken by a CCD into four parts by only a portion of the measurement object in FIG. 8.

FIG. 10 is a diagram illustrating an algorithm for widening a measurement area of a measurement object according to an embodiment of the present disclosure.

<Brief description of the main parts of the drawings>

Reference Signs List 10 pattern portion 20 light source 30 CCD 40 measurement sample 50 objective lens

60: beam splitter 70: second imaging lens 80: first imaging lens 100: translator

110: controller 120: analysis device 130: measuring unit

200, 201, 202, 203: Repetitive structures among objects

Claims (13)

 An illumination unit positioned in front of the light source to generate a pattern beam; A first imaging unit configured to form a pattern beam illuminated from the illumination unit on a measurement sample; A second imaging unit for forming a beam reflected from the measurement sample on a CCD; An analysis device for analyzing an image input from the CCD; A control unit (moving unit) for controlling the movement of the measuring unit; Height difference measuring apparatus comprising a. The method of claim 1, Analysis device Detecting the highest position of the measurement sample from the image data received from the CCD when focusing while moving downward from the position of the highest measurement unit, When focusing while moving upward from the position of the lowest measurement section, the lowest position of the measurement sample is detected from the image data received from the CCD,  A height difference measuring device, characterized by obtaining a height difference between the highest position of the measurement sample and the lowest position of the measurement sample. The method of claim 2, Analysis device A height difference measuring device, characterized in that for generating a measuring unit position control signal and transmitting to the control unit (moving unit). The method of claim 2, The light source is a height difference measuring device, characterized in that the use of white light or LED. The method of claim 2, A height difference measuring apparatus, wherein the pattern of the pattern plate is a lattice pattern. The method of claim 2, The first imaging unit is made of a first imaging lens, a beam splitter, an objective lens, The first imaging lens is provided with a pattern plate at a focal length so that the beam emitted from the light source through the pattern plate is formed at infinity, The beam splitter reflects the light passing through the first imaging lens and directs it toward the objective lens. And the objective lens makes the pattern beam incident through the beam-splitter form a pattern of the pattern plate at the focal point of the objective lens. The method of claim 6, The second imaging unit includes the objective lens, the beam splitter, and the second imaging lens, The objective lens causes the beam reflected from the sample to be reflected at infinity, The beam splitter directs the beam passing through the objective lens toward the second imaging lens, And the second imaging lens is configured to form a pattern beam incident through the beam splitter on a CCD. The method of claim 7, wherein The CCD detects an image of the pattern beam incident through the second imaging lens and transmits the image difference to the analyzer. The method of claim 8 The control unit (transport unit) is a height difference measuring apparatus characterized in that it comprises a translator, a controller.  Light source; A pattern portion formed of a plate having a lattice pattern illuminated by the light source; A first imaging lens for forming the grating pattern at infinity; A beam-splitter for transmitting the light transmitted through the imaging lens to a measurement sample; An objective lens for forming the grating pattern on the measurement sample surface with the light reflected by the beam splitter; A second imaging lens for imaging the light transmitted through the beam-splitter by imaging the measurement sample surface illuminated by the grid pattern formed by the objective lens with the objective lens; A CCD for recording an image formed by the second imaging lens; A measuring unit which is an entire system including the light source, the grating pattern plate, the first imaging lens, the beam splitter, the objective lens, the second imaging lens, and the CCD; A control unit for moving the objective lens; And An analysis apparatus including an autofocus function including software for analyzing the image recorded in the CCD and moving the objective lens to a height value of a top surface of the measurement sample or a focused position of a bottom surface of the measurement sample Height difference measuring apparatus comprising a; Moving the objective lens to a predetermined highest position; Illuminating the grating pattern beam on the measurement specimen; Passing the illuminated grating pattern through a first imaging lens and optically imaging the measurement sample through an objective lens; The grating pattern formed on the measurement sample acts as illumination light on the measurement sample to form an image of the surface where the pattern and the measurement sample are combined with the objective lens and the second imaging lens; Recording an image passing through the objective lens and the second imaging lens on a CCD; Analyzing the image recorded on the CCD to find the position of the highest surface of the measurement sample; And finding the position of the bottom surface of the measurement sample after the translator is moved to the lowest position previously determined by the control unit after finding the position of the highest surface. The method of claim 11, If the bottom is a sample with a constant height Finding the position of the bottom surface of the sample in one step; Moving the objective lens to a predetermined highest position; Illuminating the grating pattern beam on the measurement specimen; Illuminating an objective lens lattice pattern beam on the measurement specimen; Passing the illuminated grating pattern through a first imaging lens and optically imaging the measurement sample through an objective lens; The grating pattern formed on the measurement sample acts as illumination light on the measurement sample to form an image of the surface where the pattern and the measurement sample are combined with the objective lens and the second imaging lens; Recording an image passing through the objective lens and the second imaging lens on a CCD; Analyzing the image recorded on the CCD to find the position of the highest surface of the measurement sample; Moving the objective lens to another position of the measurement sample whose bottom surface is constant height after finding the position of the highest height surface; Finding the position of the highest surface in the position after the movement; Repeated to find the position of the top surface of all the regions of the floor surface height difference measuring method. In the measurement sample in which the same pattern was repeated; To find the difference between the highest position and the lowest height of several places of the measurement sample at the same time; Forcibly moving the objective lens to the lowest objective lens position; Capturing an image at each height while moving upward from the lowest objective lens position to the highest objective lens position at a constant height; Dividing the image photographed at each height into an independent area having only one pattern; Analyzing a photographed image at each height of each independent region to find a height difference value; Moving the objective lens to another area of the measurement sample after finding the height difference value; Repeatedly find the height difference measurement method of the height value of all the areas of the measurement sample.

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