JP2005172686A - Double-side machining position measuring device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a machining position simply and accurately without using a large-size casing for fixing cameras on front-and-back both sides of a work and without performing troublesome optical axis alignment, concerning the work to which microfabrication such as a circuit pattern is applied on front-and-back both faces. <P>SOLUTION: This device is equipped with an infrared camera 2 capable of imaging the image acquired by an infrared ray transmitted through the work W, and an image processing device 4 for executing prescribed operation processing based on the image imaged by the infrared camera 2. The image processing device 4 is equipped with a coordinate calculation means 9 for calculating coordinate data of each reference point (P<SB>A</SB>, P<SB>B</SB>) based on reference marks (M<SB>A</SB>, M<SB>B</SB>) on the front and back imaged on one image by the infrared camera 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a double-sided processing position measuring apparatus and method for confirming the processing position of a workpiece such as a silicon wafer that has been subjected to fine processing such as a circuit pattern on both front and back surfaces.

The IC chip improves its function by forming fine circuit patterns on both the front and back sides of a silicon wafer.
In this case, after the circuit pattern is laminated on one side of the silicon wafer by repeating the oxide film generation step-resist coating step-photo-etching step-diffusion step on the front side, the circuit pattern is similarly applied to the back side. Although a circuit pattern is formed, in this case, the circuit pattern on the front and back sides must be accurately positioned because of the connection between the front and back circuits using through holes that penetrate both the front and back sides. If so, the resist material is removed and the circuit pattern is formed again.
For this reason, there has been proposed a measuring apparatus that images each circuit pattern and measures the presence / absence of the positional deviation at the stage where the circuit patterns are formed on the front and back surfaces of the silicon wafer.
JP-A-8-201035 No. 7-3320 Japanese Patent Publication No. 7-81831

  FIG. 5 shows such a conventional measuring apparatus 41, in which an observation hole 43 for observing the wafer W from the back surface is formed in the stage 42 on which the silicon wafer W is placed, and is formed from the top to the front side of the silicon wafer W. An image pickup camera 44 for picking up the circuit pattern and an image pickup camera 45 for picking up a circuit pattern on the back surface of the wafer W through the observation hole 43 are arranged so that the respective image pickup optical axes 44x and 45x are coaxially positioned. Yes.

  According to this, when the circuit pattern is formed on the silicon wafer W, the reference marks are attached to the corresponding positions on both the front and back surfaces, and the front and back reference marks are imaged by the imaging cameras 44 and 45, and the image If the upper coordinate data is read, the imaging optical axes 44x and 45x of the imaging cameras 44 and 45 are common, and therefore the presence or absence of positional deviation can be determined from the coordinate data.

However, in order to completely match the imaging optical axes 44x and 45x of the imaging cameras 44 and 45 arranged on both sides of the silicon wafer W, with one imaging optical axis 44x fixed, to match the first XY coordinates for the other imaging optical axis 45x, further X _theta, must match the inclination of the Y _theta, the task of accurately align the optical axis was very troublesome.

  In particular, if the two cameras 44 and 45 are supported by a frame in which a plurality of parts are combined, the parts do not vibrate with each other, and sufficient rigidity for accurate positioning cannot be obtained. Therefore, it is virtually impossible to match the two imaging optical axes 44x and 45x.

Further, if the cameras 44 and 45 are supported by a large integral casting housing or the like, sufficient rigidity can be obtained without play, and positioning can be performed with high accuracy.
However, in this case, since the manufacturing cost is extremely high only by the cast casing, the manufacturing cost of the entire apparatus increases, and the commercial price of this type of measuring device reaches tens of millions of yen.

  Therefore, the present invention has a technical problem to enable easy and accurate measurement of a processing position without using a large casing for a work that has been subjected to fine processing such as circuit patterns on both sides.

  In order to solve this problem, the invention of claim 1 is directed to processing a workpiece having a reference mark having a reference point at a corresponding position on the front and back sides, and fine processing such as circuit patterns is performed on both sides. A double-sided processing position measuring apparatus for confirming a position, an infrared camera capable of capturing an image obtained by infrared rays passing through a workpiece, and image processing for executing predetermined arithmetic processing based on an image captured by the infrared camera And the image processing device includes coordinate data calculation means for calculating coordinate data of each reference point based on front and back reference marks captured on a single image by the infrared camera. And

  The double-sided processing position measuring apparatus according to claim 2 is a positional deviation amount calculation unit in which the image processing apparatus calculates a positional deviation amount between the reference points based on the coordinate data of each reference point calculated by the coordinate data calculation unit. It has.

  According to a third aspect of the present invention, there is provided a double-sided processing position measuring apparatus that includes an illuminating device that irradiates the work with epi-illumination light as necessary, while irradiating the work with infrared transmissive illumination light that passes through the work and travels toward the infrared camera.

  A double-sided processing position measuring apparatus according to a fourth aspect includes an illuminating device that emits visible light as the incident illumination light when the photosensitive characteristic of the infrared camera is from the visible light region to the infrared region.

  The invention according to claim 5 is a double-sided processing position for confirming the processing position of a work having a reference mark having a reference point at a corresponding position on the front and back sides, and fine processing such as a circuit pattern is performed on both front and back surfaces. A measuring method, using a single infrared camera arranged on one side of a workpiece, using infrared rays that are transmitted through the workpiece, the reference marks on the front and back of the workpiece are superimposed on a single image and imaged. It is characterized in that the coordinate data of each reference point is calculated based on the front and back reference marks displayed in the image.

  The double-side machining position measurement method according to claim 6 calculates the amount of positional deviation between the reference points based on the coordinate data of each reference point.

The invention according to claim 7 is a double-sided processing position measuring device for confirming a processing position of a work having a reference mark attached to a corresponding position on the front and back sides while fine processing such as a circuit pattern is performed on both front and back surfaces. The front side of the workpiece is taken as the front, and the camera that picks up the reference mark on the front and the infrared camera that picks up the back reference mark with infrared rays that pass through the work are coaxial with respect to the work. And an image processing device that is attached to an optical system that is orientated and that executes predetermined arithmetic processing based on an image captured by each camera,
The image processing apparatus includes coordinate data calculation means for calculating coordinate data of each reference point based on front and back reference marks individually captured by each camera.

  The invention according to claim 8 is a double-sided machining position measuring method for confirming a machining position of a workpiece having a reference mark at a corresponding position on the front and back sides while fine machining such as a circuit pattern is performed on both sides. The imaging optical axis of the camera that images the reference mark on the front and the infrared camera that images the back reference mark by infrared rays that pass through the work are coaxial with respect to the work. The coordinate data of each reference point is calculated on the basis of the reference marks on the front and back sides that are individually imaged by each camera.

According to the first and fifth aspects, the reference mark on both the front and back sides is imaged on a single image only by imaging the work through which infrared rays are transmitted with one infrared camera, and based on the reference mark on the front and back sides. Since the coordinate data of each reference point is calculated, the deviation of the processing position can be confirmed by comparing the values of the coordinate data, and there is an advantage that there is no need for troublesome optical axis alignment. .
In addition, since there is no need for optical axis alignment, there is no measurement error due to optical axis misalignment, and it is not necessary to support two cameras accurately at remote locations, so it is necessary to use a large integral casting case. In addition, there is an effect that the entire apparatus is small and light, can be manufactured accurately, and at low cost.

  According to the second and sixth aspects, since the positional deviation amount between the reference points is calculated based on the coordinate data of each reference point, the numerical value of the positional deviation amount can be known.

According to the third aspect, the reference mark on the back can be reliably imaged by the infrared transmissive illumination light that passes through the workpiece and travels toward the infrared camera, and the workpiece is irradiated with epi-illumination light as necessary. The reference mark can be reliably imaged.
Here, when the photosensitive characteristic of the infrared camera is from the visible light region to the infrared region as described in claim 4, visible light can also be used as the epi-illumination.

  According to the seventh and eighth aspects, since two cameras are used, that is, a camera that captures the front reference mark and an infrared camera that captures the back reference mark, the work of aligning the optical axes is required. However, since each camera can be provided close to each other by placing it on the front side of the workpiece, the members for mounting and supporting the two cameras can be small, and the entire device is large. And can be manufactured at low cost.

  In this example, for a work that has been subjected to micromachining such as circuit patterns on both front and back sides, the problem of enabling easy and accurate measurement of the machining position without using a large case is Realized by arranging one or two cameras on the side.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 is an explanatory view showing a double-sided processing position measuring apparatus according to the present invention, and FIG. 2 is a flowchart showing an image processing procedure.

A double-sided processing position measuring apparatus 1 shown in FIG. 1 detects a shift in the processing position of a silicon wafer (work) W in which circuit patterns are finely processed on both front and back surfaces.
In this type of silicon wafer W, when the front and back circuit patterns are formed without misalignment, the reference marks M _A and M _B centered on the front and back reference points P _A and P _B that overlap each other are formed on the wafer W. It is formed on the front and back.
Then, the front and back of the reference mark M _A, M _B, for example, the table is diamond, so that the back square, easy to identify its center point, and, that the shape or size at both sides are different mark preferable.
Reference mark M _A, since M _B have different shape or size, also the front and back of the circuit pattern is formed ideally without displacement, without the mark M _A, is M _B completely overlap, the one When the mark is not imaged, it can be determined that there is an abnormality.

  In the double-sided processing position measuring apparatus 1, an infrared camera 2 capable of capturing an image obtained by infrared rays transmitted from the back side of the wafer W is arranged on the front side of the wafer W, and the wafer W is transmitted from the back side of the wafer W. And irradiating the infrared camera with infrared transmission illumination light, and performing predetermined calculation processing based on the illumination device 3 that irradiates the wafer W with epi-illumination light and an image captured by the infrared camera 2 as necessary. The image processing apparatus 4 is provided.

In the illumination device 3 of this example, an optical path 6 for branching infrared light emitted from the same infrared light source 5 to be led to the back side of the wafer W and an optical path 7 to be led into the lens barrel of the camera 2 are formed. Both transmitted illumination and epi-illumination use infrared light.
In addition, although illustration is abbreviate | omitted, when the photosensitive characteristic of the infrared camera 2 has a visible light region to an infrared region, it is good also considering incident light as visible light using an infrared light source and a visible light source.
Thus, the back of the reference mark M _B is imaged by the infrared light transmitted through the reference mark M _A table will be captured by both the infrared transmitted light and reflected light.

The image processing device 4 calculates the coordinate data of the respective reference points P _A and P _B that are the center points based on the front and back reference marks M _A and M _B imaged on one image by the infrared camera 2. _A positional deviation amount for calculating a positional deviation amount between the reference points P _A and P _B based on the coordinate data calculating means 8 and the coordinate data of the respective reference points P _A and P _B calculated by the coordinate data calculating means 8 Calculation means 9 is provided.

FIG. 2 is a flowchart showing a processing procedure in the image processing apparatus 4. First, in step STP 1, the front and back images projected on the image by pattern recognition based on the shape of a reference mark (for example, a rhombus and a square) registered in advance. The reference marks M _A and M _B are identified.
Then, as shown in FIG. 3, in step STP2, as the coordinate data of the reference point P _A to the intersection of the diagonals on the basis of the four coordinates of the vertices A ₁ to A ₄ to be read from the reference mark M _A diamond table calculate.
Then, at step STP3, and calculates the intersection of diagonal lines as the coordinate data of the reference point P _B on the basis of the four coordinates of the vertices B ₁ .about.B ₄ to be read from the reference mark M _B of the back of the square.
Then, it goes to step STP4, each reference point P _A, based on the coordinate data of P _B, by calculating the reference point P _A, the positional deviation amount between the P _B, whether the front and back of the circuit pattern is how much deviation Can be measured accurately.
Finally, in step STP5, the positional deviation amount calculated in step STP4 is compared with a preset allowable positional deviation amount, and if this is within the allowable range, the process ends. If it is larger than the allowable range, step STP6 is entered. Then, the positional deviation amount calculated in step STP4 is output.

  Note that the processing of steps STP1 to STP4 is a specific example of the coordinate data calculation means 8, and step STP5 is a specific example of the positional deviation amount calculation means 9.

Figure 4 shows a second embodiment of the present invention, both surfaces processing position measuring device 11 of this embodiment, the one side of the wafer (work) W and the table, the camera 12A and the wafer W to image the reference mark M _A table infrared camera 12B for imaging the back of the reference mark M _B by infrared radiation transmitted through is attached to the imaging optical axis X _a and X _B each in an optical system 13 oriented coaxially from the table relative to the wafer W Yes.

The image processing device 14 is configured to execute a predetermined calculation process based on images captured by the cameras 12A and 12B. The front and back reference marks M _A and the individual images captured by the cameras 12A and 12B are provided. husband based on M _B 's reference point P _a, and a coordinate data calculating means 15 for calculating the coordinate data of the P _B.

The cameras 12A and 12B have the same imaging magnification.
Thereby, even if the coordinates of the respective reference points P _A and P _B are calculated based on the individual images captured by the cameras 12A and 12B, they can be handled as data by the same coordinates.
Moreover, the camera 12A for imaging the table so that it can not be captured only reference marks M _A table The camera 12B for imaging the back so as not only be imaged behind the reference mark M _B, the depth of field is set ing.
Thus, since there is no possibility that two reference mark M _A and M _B are simultaneously imaged, reference marks M _A, no problem even using the mark having the same shape and size as M _B.

Then, in the same manner as in Example 1, based on the table of the image captured by the camera 12A, the image processing apparatus 14 the coordinate data of the reference point P _A is the center point of the reference mark M _A table is calculated, infrared based on the back of the image captured by the camera 12B, the coordinate data of the reference point P _B is the center point of the back of the reference mark M _B is calculated.
Then, the respective reference point P _A, based on the coordinate data of P _B, by calculating the reference point P _A, the positional deviation amount between the P _B, to accurately measure how the front and back of the circuit pattern is how much deviation Can do.

The work is not limited to a silicon wafer, and can be applied to an arbitrary work made of an infrared transmitting material.
Further, the reference point is not limited to using the center point, and any point that can be specified from the reference mark can be used.

As described above, according to the present invention, the reference marks on both the front and back sides of the workpiece can be simultaneously captured on one image with one infrared camera arranged on one side of the workpiece. It is not necessary to align the optical axes, and the processing positions on both the front and back surfaces can be measured extremely easily and accurately.
Also, when using two cameras for imaging the front and back surfaces of the workpiece, the work of aligning the optical axes is necessary, but both cameras are placed on one side of the workpiece surface. In addition, since the cameras can be provided close to each other, a member for mounting and supporting the two cameras may be small, and the entire apparatus can be manufactured at a low cost without increasing the size.

  As described above, the present invention can be applied to the use of product inspection for confirming the processing position of a workpiece such as a silicon wafer that has been subjected to fine processing such as a circuit pattern on both front and back surfaces.

Explanatory drawing which shows the double-sided processing position measuring device which concerns on this invention. 5 is a flowchart showing a processing procedure of the image processing apparatus. Explanatory drawing which shows the imaged image. Explanatory drawing which shows another Example. Explanatory drawing which shows a conventional apparatus.

Explanation of symbols

1,11 Double-sided processing position measuring device W Silicon wafer (work)
P _{A, P B} reference points _M A, _{M B} reference mark 2 infrared camera 3 illuminating device 4,14 image processing apparatus 12A camera 12B infrared camera

Claims (8)

It is a double-sided processing position measuring device that confirms the processing position of a workpiece with a reference mark having a reference point at the corresponding position on the front and back, as well as fine processing such as a circuit pattern on both front and back surfaces,
An infrared camera capable of capturing an image obtained by infrared rays that pass through the workpiece, and an image processing device that executes predetermined arithmetic processing based on the image captured by the infrared camera;
The double-sided processing position, wherein the image processing apparatus includes coordinate data calculation means for calculating coordinate data of each reference point based on front and back reference marks captured on one image by the infrared camera. Measuring device.   The double-sided processing position according to claim 1, wherein the image processing apparatus includes a positional deviation amount calculation unit that calculates a positional deviation amount between the reference points based on the coordinate data of each reference point calculated by the coordinate data calculation unit. Measuring device.   The double-sided processing position measuring apparatus according to claim 1, further comprising an illuminating device that irradiates the workpiece with infrared transmission illumination light that passes through the workpiece and travels toward the infrared camera, and irradiates the workpiece with epi-illumination light as necessary.   The double-sided processing position measuring apparatus according to claim 3, further comprising an illuminating device that emits visible light as the epi-illumination light when a photosensitive characteristic of the infrared camera is from a visible light region to an infrared region. It is a double-sided processing position measurement method for confirming the processing position of a workpiece with a reference mark having a reference point at a corresponding position on the front and back, as well as fine processing such as a circuit pattern on both the front and back surfaces,
Using one infrared camera placed on one side of the workpiece, the reference marks on the front and back of the workpiece were superimposed on a single image using infrared rays transmitted through the workpiece, and displayed on that image. A double-sided processing position measuring method, wherein coordinate data of each reference point is calculated based on front and back reference marks.   The double-sided processing position measuring method according to claim 5, wherein a positional deviation amount between the reference points is calculated based on the coordinate data of each reference point. It is a double-sided processing position measurement device that confirms the processing position of a workpiece that has been subjected to fine processing such as a circuit pattern on both the front and back surfaces, and a reference mark attached to the corresponding position on the front and back surfaces,
A camera that images one side of the workpiece as a front, and a camera that images the front reference mark and an infrared camera that images the back reference mark using infrared rays that pass through the workpiece, each imaging optical axis is coaxial with respect to the workpiece from the front. An image processing device that is attached to an optical system that is oriented, and that executes predetermined arithmetic processing based on an image captured by each of the cameras;
The double-sided processing position measurement apparatus according to claim 1, further comprising coordinate data calculation means for calculating coordinate data of each reference point based on front and back reference marks individually captured by each camera. It is a double-sided processing position measurement method for confirming the processing position of a workpiece with a reference mark at the corresponding position on the front and back, as well as fine processing such as circuit patterns on both front and back surfaces,
With one side of the workpiece as the front, the imaging optical axis of the camera that images the front fiducial mark and the infrared camera that captures the back fiducial mark with infrared rays that pass through the workpiece are oriented coaxially from the front with respect to the workpiece. And
A double-sided processing position measuring method, comprising: calculating coordinate data of each reference point based on front and back reference marks individually captured by each camera.

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