JP2008046027A - Height measuring method and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform measurement in less time, thus increasing throughput using a simple device by measuring the height of an inspection object using image data obtained by one image pickup operation. <P>SOLUTION: An image pickup device A comprises an image pickup lens 1, a beam splitter 2 which bisects incidence light from the inspection object B, and CCDs 3, 4 which receive the bisected light through optical path length adjustment means 5, 6, respectively. Image pickups are done by the CCDs 3 and 4 in such a state that the CCDs 3 and 4 are out of image forming positions, respectively by the optical path length adjustment means 5, 6 after setting so as to form an image to the CCDs 3, 4 after bisecting of the incidence light from the inspection object B and the optical path lengths from image forming lenses should be d<SB>q1</SB>and d<SB>q2</SB>, respectively. d<SB>i</SB>is determined as the quantity regarding the height of the inspection object from the positional coordinates of d<SB>q1</SB>and d<SB>q2</SB>and their interval h, and the ratio R of light intensities at both the positions in an operation processing part 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for measuring the height of an object to be inspected and an apparatus therefor, and in particular, to measuring a minute height such as irregularities on the surface of a semiconductor element in a manufacturing process. The present invention relates to a method for measuring the height of an object to be inspected and an apparatus therefor.

  Miniaturization and high functionality are rapidly progressing in various digital devices such as information terminal devices such as mobile phones, portable information processing devices, and game machines. It has become indispensable. In ICs such as CPU and memory, which are the central part of digital equipment, the form of leads has been improved from SOP to BALL and further to BUMP. Lead from millimeters to BUMP of several hundred microns, along with the increasing demand for dimensional inspection accuracy, and the height of BUMP is particularly important in the joining in the manufacturing process, so measure the height with high accuracy Is now required.

  Triangulation method, confocal method, white light interferometry, etc. are used to measure the height of BUMP and the like. Of these, the triangulation method has a measurement accuracy of about a few microns, and cannot be used when BUMP is further reduced in the future. The confocal method and the white interference method are methods having high measurement accuracy and useful in research. However, if they are used in the manufacturing process, the throughput becomes low and becomes impractical.

As a technique related to the height measuring method, it is described in the following documents.
JP 2003-42720 A JP-A-9-105615 Japanese Patent Laid-Open No. 2-87005

  In Patent Document 1, two confocal images are picked up by changing the relative position between the condensing position of the objective lens of the confocal microscope and the sample, and a photodetector is provided for each corresponding pixel of each confocal image. A height measuring apparatus is described in which the height at each point of the sample is obtained by calculating the difference / sum of outputs or the division value.

  In Patent Document 2, a confocal image is captured at each of a plurality of different height positions in a sample, a height position at which the light intensity reaches a peak is obtained for each pixel, and the highest peak height position corresponds to that pixel. It describes three-dimensional measurement as sample surface information.

  In Patent Document 3, a measurement beam is collected on the surface of an object to be measured, a reflected light having surface unevenness information is interfered with a reference beam having a different frequency, and a measurement beat signal is extracted and its phase is extracted. It describes a surface shape measuring device that measures the uneven shape of a surface based on changes.

  In the device described in Patent Document 1, in order to obtain the height at each point of the sample, it is necessary to capture a confocal image at two height positions sandwiching the surface of the sample, and two imaging operations are performed. It is essential. The point that imaging is indispensable twice in order to obtain the height is the same as in Patent Document 2, and the method for obtaining the height in this way increases the time required for the process of obtaining the height. When applied in an actual semiconductor device manufacturing process, the throughput is reduced.

  Although the measurement accuracy can be increased with the interference between the measurement beam and the reference beam as in Patent Document 3, the optical system and the signal processing circuit for that purpose are complicated and large-scale, and the throughput cannot be increased. .

  In this way, when measuring a very small height, such as unevenness on the surface of a semiconductor element in the manufacturing process, in the method of capturing confocal images at two different positions, Since at least the time required for two times of imaging is required, the throughput is reduced. In addition, the method using the beam interference increases the size of the apparatus and is not effective in increasing the throughput. For this reason, there has been a demand for a method for measuring the height in a shorter time using a relatively simple apparatus.

（ただし、ｄ_ｉは撮像レンズから被検査体の基準面までの距離、ｄ_ｏは撮像レンズから被検査体の基準面上の点の結像面までの距離、Δｄ_ｏ１＝ｄ_ｏ−ｄ_ｑ１である。）を用いて前記撮像レンズから前記被検査体までの距離ｄ_ｉを求めることにより被検査体における高さを測定するものである。 The present invention has been made to solve the above-mentioned problems, and the method for measuring the height according to the present invention uses first and second light beams transmitted through an imaging lens having a focal length f from the object to be inspected, respectively. A method of measuring the height of the object to be inspected using image data obtained by an imaging device that is received by the equivalent first and second imaging elements via the optical path length adjusting means, Setting by the first optical path length adjusting means so that the first image sensor is at a first optical position deviating from the imaging position of light from the object to be inspected, and the second image sensor Is set by the second optical path adjusting means so that the second optical position is deviated from the imaging position of the light from the object to be inspected, and the first and second imaging from the imaging lens The optical distance (d _{q1) to} one of the elements ) And the optical path difference (h) from the first optical position to the second optical position, and the first optical position deviated from the imaging position by the imaging operation of the imaging device. The first and second imaging elements simultaneously image the inspected object, and the light intensity ratio (R) obtained by the first and second imaging elements, respectively, is obtained for each pixel. From d _q1 , h, R and the focal length f,

(Where d _i is the distance from the imaging lens to the reference plane of the object to be inspected, d _o is the distance from the imaging lens to the image plane of the point on the reference plane of the object to be inspected, and Δd _o1 = d _o −d _q1 The height of the object to be inspected is measured by obtaining a distance d _i from the imaging lens to the object to be inspected.

After the first and second imaging elements are set to the imaging positions of light from the object to be inspected and information on the positions is acquired, the optical positions of the first and second imaging elements are respectively imaged. By setting the first and second optical positions out of position, the distance (d _q1 ) from the imaging lens to the optical position of one of the first and second imaging elements and the first The height in the object to be inspected according to claim 1, wherein the optical path difference (h) from the optical position to the second optical position is obtained.

  An apparatus for measuring height according to the present invention includes an imaging lens, a beam splitter that bisects light transmitted through the imaging lens, and one of the lights bisected by the beam splitter is a first light. The first image sensor disposed at the position where the image is formed via the optical path length adjusting means and the position where the other of the bisected lights is imaged via the second optical path length adjusting means. A second image sensor provided, an image pickup operation unit for simultaneously picking up images with the first and second image sensors, and image data obtained by image pickup with the first and second image sensors. And an arithmetic processing unit that calculates the height of the object to be inspected, and the first optical path length adjusting means converts one of the bisected lights into the first imaging element. It is possible to adjust the state where the image is formed at the position and the state where it is out of the image formation state. The second optical path length adjusting means can be adjusted to a state in which the other of the bisected lights is imaged at the position of the second image sensor and a state outside the imaging state, The arithmetic processing unit includes the image data obtained by simultaneously performing imaging by the imaging operation unit in a state where the first and second imaging elements are out of the imaging state, and the first and second imaging elements. The height of the object to be inspected is obtained by performing arithmetic processing based on the optical distance indicating the degree to which the lens is out of the imaging state.

  In the apparatus for measuring the height, the first and second optical path length adjusting means continuously variably adjust the distance from the imaging lens to the first and second imaging elements through the beam splitter, respectively. You may make it do.

  In the apparatus for measuring the height, each of the first and second optical path length adjusting means adjusts the optical path length by inserting or removing an optical member having a predetermined thickness in the optical path. May be.

（ただし、ｄｉは撮像レンズから被検査体の基準面までの距離、ｄｏは撮像レンズから被検査体の基準面上の点の結像面までの距離、Δｄｏ１＝ｄｏ−ｄｑ１である。）を用いて前記撮像レンズから前記被検査体までの距離ｄ_ｉを求めることにより被検査体における距離を測定するようにしてもよい。 In the apparatus for measuring the height, the arithmetic processing unit sets the focal length of the imaging lens to f, and optically extends from the imaging lens to one of the first and second imaging elements. The distance is d _q1 , the optical path difference from the optical position of the first image sensor to the optical position of the second image sensor is h, and the intensity of light obtained by each of the first and second image sensors Let R be the ratio of

(Where, di is the distance from the imaging lens to the reference surface of the object to be inspected, do is the distance from the imaging lens to the image plane of the point on the reference surface of the object to be inspected, and Δdo1 = do−dq1). The distance d _i from the imaging lens to the object to be inspected may be used to measure the distance in the object to be inspected.

According to the present invention, images at two different perspective positions can be obtained by performing one imaging operation on two imaging elements, and the height of the object to be inspected can be calculated from the image data. Therefore, the throughput is, for example, 10,000 cm ² / In addition, the accuracy is as high as several hundreds of nanometers in terms of accuracy, and the cost can be reduced because measurement can be performed with a relatively simple configuration.

[Characteristics of imaging optical system]
The microscope optical system is used in the height measuring method and the measuring apparatus therefor according to the present invention. The basic characteristics of the optical system will be described.

FIG. 1 shows an optical system that is used to image the surface of an object to be measured in order to measure the height of the surface of the object to be inspected. In FIG. The reference plane of the lens L (considering the main surface as the lens system) is α. Point P on the inspected object B is from the reference plane α under the lens L on the vertical plane β to the optical axis at the position of the distance d _i, the lens L image of the point P is on the right of the lens L is the point Q formed on a plane perpendicular γ plane to the optical axis from the reference plane α at a distance d _o. A surface front (lens L side) by a distance d _o1 from the imaging surface γ is γ ₁ , a surface behind the imaging surface γ by a distance d _o2 is γ _2, and a distance from the reference surface α to the surface γ ₁ is d. _q1, the distance from the reference plane α to the surface gamma ₂ and _{d q2.}

となり、また、ｄ_ｏ／ｄ_ｉ＝ｘ_ｏ／ｘ_ｉ＝ｙ_ｏ／ｙ_ｉ＝ｍとして

のように座標変換をすると、Ｓは

となる。
さらに、ｎ次の第１種ベッセル関数Ｊ_ｎ（ｘ）の関係式

を用い、ｘ＝−（２π／λ）ρω、 ｎ＝０として、

となる。この波面がｄ_ｑ１の位置に作る波面は、Δｄ_ｏ１＝ｄ_ｏ−ｄ_ｑ１とすると、ｄ_ｏの位置からｄ_ｑ１の面までのフーリエ変換で与えられる。ｄ_ｑ１における座標を（ｘ_ｏ１，ｙ_ｏ１）として、

となる。これは逆フーリエ変換であるから、

となり、ｇ（ｘ_ｏ１，ｙ_ｏ１）は、半径がＤ／２＝（−ｘ_ｏ１／Δｄ_ｏ１）ｄ_ｏ／２で（つまりｘ_ｏ１＝−ＤΔｄ_ｏ１／ｄ_ｏ）、面積が（１／Δｄ_ｏ１）^２に比例した値となる。 When d _i and d _o satisfy the conditions of the imaging relationship, the point response function of the microscope is

Next, _also as _{d o / d i = x o} / x i = y o / y i = m

If the coordinate transformation is

It becomes.
Further, a relational expression of the nth-order first-type Bessel function J _n (x)

X = − (2π / λ) ρω, n = 0,

It becomes. The wavefront created by this wavefront at the position of d _q1 is given by Fourier transform from the position of d _{o to} the plane of d _q1 when Δd _o1 = d _o −d _q1 . The coordinates in d _q1 are (x _o1 , y _o1 ),

It becomes. Since this is an inverse Fourier transform,

G (x _o1 , y _o1 ) has a radius of D / 2 = (− x _o1 / Δd _o1 ) d _o / 2 (that is, x _o1 = −DΔd _o1 / d _o ) and an area of (1 / Δd) _o1 ) A value proportional to ² .

As described above, in a range where Δd _o1 is small, the point response function g _o1 (x _o1 , y _o1 ) indicating the intensity of light emitted from one point and passing through the imaging lens is proportional to (1 / Δd _o1 ) ² . is the value, the image is spread with [Delta] d _o1, intensity decreases in inverse proportion to the square of the [Delta] d _o1.

  FIG. 2A shows the light intensity distribution on the light receiving surface after the light emitted from one point of the object to be inspected passes through the imaging lens. The horizontal axis indicates the position on the light receiving surface (imaging device), and the vertical axis. Indicates strength. The curve with the highest peak and the smallest spread is when the light receiving surface is at the imaging position of the imaging lens, and the curve gradually becomes lower and wider as the light receiving surface deviates from the imaging position.

  In the case where the light from the inspected object is not a single point but light from a portion having a width of about 20 μm, for example, there is light from not only one point but also a nearby point, so the light intensity is as shown in FIG. The shape is as shown in (b). In FIG. 2B, the horizontal axis indicates the position in the width direction of the object to be inspected, and has a contrasting intensity distribution with respect to the center of the width direction portion.

FIG. 2C shows how the intensity of the reflected light changes due to the portion of the position in the width direction of the object to be inspected when the position of the light receiving surface deviates from the imaging position in FIG. The horizontal axis represents the deviation Δd _o1 of the light receiving surface from the imaging position, and the vertical axis represents the intensity. In this case, Δd _o1 is not so large. The uppermost curve is the intensity distribution for the portion at the center position in the width direction in FIG. 2B, and the lower curve shows the intensity distribution for the portion at the next position close to the center in the width direction, In the following, the intensity distribution of the adjacent portions is shown. Each curve has a different intensity distribution, but the intensity decreases in inverse proportion to the square of Δd _{o1 in} the range where Δd _o1 is small.

[Principle of height calculation]
As described above, the intensity of the image on the imaging surface by the microscope imaging optical system is proportional to (1 / Δd _o1 ) ² in a small range of Δd _{o1 where} Δd _o1 is the distance in the optical axis direction from the focal point. However, measurement of the height of the inspection object using this property will be described.

  When the height is measured by the intensity of light detected by a detection element having a plurality of pixels, such as a CCD, the test object corresponding to each pixel constituting the image obtained by imaging the surface of the test object The intensity of light from the body part is detected. Light reaching each pixel from the surface of the object to be inspected may have a uniform height or a non-uniform height on the surface corresponding to one pixel of the object to be inspected.

であり、２つの面γ_１、γ_２における強度の比Ｒは

となるから、ｈ＝｜ｄ_ｑ１−ｄ_ｑ２｜とすると、上式は

となる。これから、Δｄ_ｏ１がｈとＲで表され、さらにｄ_ｏ１＝ｄ_ｑ１＋Δｄ_ｏ１もｈとＲで表される。これらの関係とレンズの結像状態を示す

とからｄ_ｉが

として計算される。このようにして被検査体における高さを特徴づけるｄ_ｉが求められる。 (1) When the height is uniform In FIG. 1, the reflection intensity at the surface γ ₁ is proportional to (1 / Δd _o1 ) ² , and the reflection intensity at the surface γ ₂ is

And the intensity ratio R of the _two surfaces γ ₁ and γ ₂ is

_Therefore , if h = | d _q1 -d _q2 |

It becomes. From this, Δd _o1 is represented by h and R, and d _o1 = d _q1 + Δd _o1 is also represented by h and R. Shows these relationships and the imaging state of the lens

And d _i

Is calculated as Thus d _i characterizing the height at the object to be inspected is determined.

(2) the height is assumed that the height of the portion in the inspection object corresponding to one pixel when the heterogeneous is continuously changed, and, in its continuous change, d _i in FIG. 1 and changes in d _o is assumed to be small. In fact, if the height problem of the semiconductor element, d _i is a few tens mm, a height change is a few tens of [mu] m, the variation is about 1/1000, also, d _o dozens Since the change is several hundred μm with respect to mm, it is also about 1/100.

であり、また、面γ_２において各画素の受ける総光量Ｉ_２は

となる。したがって、面γ_１と面γ_２とにおいて受ける強度の比Ｒは

である。これは（１）と比較すると、その画素の受ける強度の最大値と最小値との相乗平均になっている。実際に受光素子の各画素が受ける強度はこのような相乗平均として得られるものであるので、高さが不均一の場合にも（１）式を用いてｄ_ｉが求められる。 The intensity of incident light in each pixel is given by the integral of the intensity of reflected light from a point on the surface of the corresponding inspection object part. If now the included from the height d _os as a component of the portion of the test subject corresponding to each pixel to d _oe, total light amount I ₁ received by the pixels in the plane gamma ₁ is

, And the The total amount of light I ₂ received by the respective pixels in the plane gamma ₂ is

It becomes. Therefore, the ratio R of the strength received at the surface γ ₁ and the surface γ ₂ is

It is. Compared with (1), this is the geometric mean of the maximum and minimum values of the intensity received by the pixel. The intensity actually each pixel of the light receiving element receives are those obtained as such a geometric mean, d _i is determined height with even (1) the case of heterogeneous.

Thus, two positions before and after the focal point, d _i as information indicating the height at the object to be inspected from the received light intensity ratio at intervals and their positions at those positions is determined.

[Device for height measurement]
When the height of the object to be inspected is actually measured according to the present invention using the above-described principle of calculating the height, an apparatus for measuring the height as shown in FIG. 3 is used. In FIG. 3, the apparatus for measuring the height performs control for imaging unit A of the object to be inspected, control for imaging at imaging unit A, and calculation processing for obtaining the height from the captured image data. And a processing unit C.

  The imaging unit A includes an imaging lens 1, a beam splitter 2 that bisects light transmitted through the imaging lens 1, an imaging device (CCD) 3 that receives light transmitted through the beam splitter 2, and an imaging device that receives light reflected by the beam splitter 2. (CCD) 4, CCD 3 is stored in storage section 3 a, and CCD 4 is stored in storage section 4 a. An optical path length adjusting means 5 is interposed between the beam splitter 2 and the CCD 3, and an optical path length adjusting means 6 is interposed between the beam splitter 2 and the CCD 4, and these are integrally accommodated in a housing. The connecting portion 7 is integrally attached to the casing. The imaging device A is attached to a column 21 attached to a mounting table 20 for mounting an object B to be inspected by a connecting portion 7. At the portion where the connecting portion 7 is attached to the support column 21, the position can be adjusted by a rack and pinion mechanism or the like, whereby the position of the imaging device A with respect to the inspection object B placed on the mounting table 20 is set in the optical axis direction. Make it adjustable.

  The CCD 3 and the CCD 4 are equivalent in terms of sensitivity and resolution, and the optical path length adjusting means 5 and 6 are configured such that the length in the optical axis direction can be continuously changed by, for example, a helicoid, or for adjusting the optical path length. The optical member may be inserted into or removed from the optical path. When the optical member is inserted / removed, the optical path length changes stepwise, but multi-step adjustment is possible by preparing a plurality of optical members having different refractive indices or thicknesses.

  The image pickup apparatus A has a function of adjusting so that the light transmitted through the image pickup lens 1 can be changed into a state where the light is focused on the surfaces of the CCD 3 and the CCD 4 and a state where the light is out of the focus state. There are a mode in which the distance from the imaging lens 1 to the respective CCDs 3 and 4 via the beam splitter 2 can be adjusted, and a mode in which focusing adjustment is performed by the imaging lens 1. If the optical path length adjusting members 5 and 6 are continuously variably adjusted or the optical path length adjusting members are not continuously variable, the positions of the CCDs 3 and 4 are adjusted in the optical axis direction in the respective CCD storage portions 3a and 4a. Keep it available. In the case where the focus adjustment is performed by the imaging lens 1, the imaging lens 1 is set so that the CCD 3 and the CCD 4 can be focused at the same time, and then the focusing lens can be adjusted. These position adjustment and focus adjustment may be performed manually. However, an actuator may be provided at a position where the adjustment is performed, and drive control may be performed. In order to perform focusing automatically, a focus detection unit is provided, and the position control of the imaging lens or the CCD is performed based thereon. In the case of manually adjusting the focus position, the position of the imaging lens or CCD is adjusted while viewing the monitor image. In the imaging apparatus A, it is assumed that imaging can be performed simultaneously by the CCD 3 and the CCD 4 with one release operation, and the imaging apparatus is further provided with illumination means.

  The control / processing unit C includes an arithmetic processing unit 11 that calculates the height of the object to be inspected based on image data obtained by imaging with the CCD 3 and the CCD 4, a control unit 12 that controls imaging with the imaging device A, and an imaging device. And a display unit 13 for monitoring the image of A and displaying necessary data for the arithmetic processing. The controller 12 adjusts the position of the optical path adjusting means 5 and 6 and the CCDs 3 and 4 and the focusing operation by the imaging lens 1 by an actuator, performs imaging by the imaging device A in response to a command from the controller 11, and The control unit 12 receives data such as the optical path length from the imaging device A and transfers the data to the arithmetic processing unit 11. The arithmetic processing unit 12 includes storage means for image data and optical path length data, and calculates the height based on the set data, input or transferred data.

  In the form of the apparatus of FIG. 3, the adjustment of the optical path length from the image pickup apparatus A and the imaging operation are performed in accordance with a command from the control unit 12 of the control / processing unit C, and data such as the optical path length is further transmitted from the control unit 12. It is transferred to the arithmetic processing unit 11 and adjustment of the optical path length and calculation processing are performed on the control / processing unit C side, but adjustment of the optical path length and the like are manually performed in the imaging apparatus A. In the embodiment, the function of the control unit 12 is moved to the imaging apparatus A side or omitted. In such an apparatus form, the control / processing unit C includes the arithmetic processing unit 11 and the display unit 13, and a general-purpose personal computer (PC) having a necessary arithmetic program may be used. In this case, it is necessary to input data such as the optical path length set in the imaging apparatus A to the PC.

[Procedure for measuring height]
The procedure of the method for measuring the height of the object to be inspected using the apparatus for measuring the height as shown in FIG. 3 will be described.
After mounting the inspection object B on the mounting table 20, the imaging apparatus A adjusts so that the image of the inspection object B is formed on the CCD 3 and the CCD 4. The optical path length data at this time is held in the storage means in the arithmetic processing unit 11.

  Thereafter, the optical path lengths reaching the CCD 3 and the CCD 4 are changed and adjusted so as to be out of the in-focus position. The amount to be removed from the in-focus position by this adjustment is related to the calculation of the height, and it is preferable to prescribe each of the CCDs 3 and 4 as standard amounts to some extent. In the case where the optical member for adjusting the optical path length is inserted and removed, the optical member that gives the optical path length deviated from the standard in-focus position is inserted and removed. When the optical path length is adjusted, the adjusted optical path length data is sent to the arithmetic processing unit 11, and the optical path length data is stored in the storage means.

  After adjusting the optical path length so as to deviate from the in-focus position, imaging is performed by the imaging apparatus A, and the image data of the object to be inspected respectively obtained by the CCD 3 and the CCD 4 is stored in the storage means of the arithmetic processing unit 11.

  The arithmetic processing unit 11 calculates the height using the image data of the object to be inspected and the optical path length data respectively obtained by the CCD 3 and the CCD 4. The calculation of the height is performed by the equation (1) using the luminance value and the optical path length difference at the corresponding pixels of the CCD 3 and the CCD 4, respectively.

  FIG. 4 shows a flow of measuring the height of the object to be inspected according to the present invention. In this flow, first, after adjusting the position of each CCD so that the light from the object to be imaged is formed on each of the two CCDs, each CCD is removed from the imaging state by the optical path length adjusting means. However, after setting the imaging device to a position for imaging with respect to the object to be inspected, the height of the other part of the object to be inspected is measured by relatively moving the imaging device and the object to be inspected perpendicular to the optical axis. In this case, since the imaging state of each image sensor is maintained, the data on the imaging device side obtained at the time of adjustment to the first imaging position is stored and held in the arithmetic processing unit. Thus, in the subsequent height measurement, the height measurement is performed without the process of adjusting the image pickup device again so as to be in the imaging state.

  As described above, according to the present invention, the height of the object to be inspected can be obtained by one imaging operation using the imaging device having two CCDs and the arithmetic processing of the data obtained thereby.

It is a figure which shows the optical principle of the measurement of height by this invention. (A) It is a figure which shows distribution of the intensity | strength in the light-receiving surface after the light from one point passes an imaging lens. (B) It is a figure which shows distribution of the intensity | strength in the light-receiving surface after the light from the object with a width | variety passed an imaging lens. (C) It is a figure which shows how the intensity | strength of light changes according to the shift | offset | difference of the position of the light-receiving surface from the imaging position of an imaging lens for every position of the width direction of the object in (b). It is a figure which shows the structure of the apparatus for measuring the height by this invention. It is a figure which shows the flow of the measurement of the height by this invention.

Explanation of symbols

A Imaging unit B Inspected object C Control / processing unit 1 Imaging lens 2 Beam splitter 3 CCD
4 CCD
5 Optical path length adjusting means 6 Optical path length adjusting means 11 Arithmetic processing part 12 Control part 13 Display part

Claims (6)

It is obtained by an imaging apparatus in which light transmitted through an imaging lens having a focal length f from an object to be inspected is received by equivalent first and second imaging elements via first and second optical path length adjusting units, respectively. A method for measuring the height of the object to be inspected using image data,
Setting by the first optical path length adjusting means so that the first imaging device is at a first optical position deviating from the imaging position of light from the object to be inspected;
Setting by the second optical path adjusting means so that the second imaging element is at a second optical position deviating from the imaging position of the light from the object to be inspected;
An optical distance (d _q1 ) from the imaging lens to one of the first and second imaging elements, and an optical path difference from the first optical position to the second optical position ( h) and
The inspected object is simultaneously imaged by the first and second imaging elements at optical positions deviated from the imaging position by the imaging operation of the imaging device, respectively, and obtained by the first and second imaging elements, respectively. Determining the ratio (R) of the intensity of the emitted light for each pixel;
From the obtained d _q1 , h, R and the focal length f,

(Where, di is the distance from the imaging lens to the reference surface of the object to be inspected, do is the distance from the imaging lens to the image plane of the point on the reference surface of the object to be inspected, and Δdo1 = do−dq1). A method of measuring the height of the object to be inspected by using a distance d _i from the imaging lens to the object to be inspected. After the first and second imaging elements are set to the imaging positions of light from the object to be inspected and information on the positions is acquired, the optical positions of the first and second imaging elements are respectively imaged. By setting the first and second optical positions out of position, the distance (d _q1 ) from the imaging lens to the optical position of one of the first and second imaging elements and the first 2. The method for measuring the height of an object to be inspected according to claim 1, wherein the optical path difference (h) from the optical position to the second optical position is obtained.   An imaging lens, a beam splitter that bisects the light that has passed through the imaging lens, and one of the light that is bisected by the beam splitter is disposed at a position where an image is formed via the first optical path length adjusting means. A first image sensor, a second image sensor disposed at a position where the other of the bisected lights forms an image via a second optical path length adjusting means, and An imaging operation unit for performing imaging simultaneously with the second imaging device, and an operation for calculating the height of the object to be inspected by calculating the image data obtained by imaging with the first and second imaging devices. A processing unit, wherein the first optical path length adjusting unit forms an image of one of the bisected lights at the position of the first image sensor and a state deviated from the imaging state. And the second optical path length adjusting means is bisected. Can be adjusted to a state in which the other light is imaged at the position of the second imaging element and a state outside the imaging state, and the arithmetic processing unit is configured so that the first and second imaging elements are respectively Based on image data obtained by simultaneous imaging by the imaging operation unit in a state deviating from the imaging state and an optical distance indicating the degree to which the first and second imaging elements deviate from the imaging state. A device for measuring the height, characterized in that the height of the object to be inspected is obtained by performing an arithmetic process.   The first and second optical path length adjusting means continuously variably adjust distances from the imaging lens to the first and second imaging elements through the beam splitter, respectively. 3. A device for measuring the height according to 3.   The said 1st and 2nd optical path length adjustment means adjusts an optical path length by inserting or removing the optical member which respectively has predetermined | prescribed thickness in an optical path. A device for measuring the height of an object. The arithmetic processing unit has a focal length of the imaging lens as f, an optical distance from the imaging lens to one of the first and second imaging elements as d _q1 , and the first imaging element. The optical path difference from the optical position to the optical position of the second image sensor is h, and the ratio of the intensity of light obtained by the first and second image sensors is R,

(Where d _i is the distance from the imaging lens to the reference plane of the object to be inspected, d _o is the distance from the imaging lens to the image plane of the point on the reference plane of the object to be inspected, and Δd _o1 = d _o −d _q1 in a.) any one of the claims 3-5, characterized in that so as to measure the distance in the object to be inspected by obtaining the distance d _i from the imaging lens to the object to be inspected using a A device for measuring the height described in 1.

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