JP2009198336A - Optical height/step measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten measurement accuracy of an optical height/step measuring device, and to shorten a measuring time. <P>SOLUTION: In this measuring device for measuring the size in the Z-direction of a measuring object by detecting a moving amount in the Z-direction by means of detection operation of a focusing point of a target mark image projected onto the measuring object moving relatively in the Z-direction, a wedged prism 11 having a pair of wedged parts combined so as to obtain opposite wedge directions is arranged so that an illumination light flux is halved in a direction orthogonal to an optical axis and deflected to an opposite direction, and a plurality of target marks arranged so as to stride over the halved light flux are provided on a projection original plate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical height / level difference measuring device that measures the height and level difference of a target object without contacting the object to be measured, and more specifically, measurement is performed by detecting a focal point of a target mark image projected on the target object. Relates to the device to perform.

  For example, when measuring the height or level difference of an object to be measured such as an electronic part such as an IC or a precision machined part, a height / level difference measuring device is used. When measuring the height or level difference of the object to be measured, a contact-type measuring device (for example, Patent Document 1) for bringing a measuring element into contact with the object to be measured and an operation for detecting a focal point of a target mark image projected on the object to be measured. An optical measuring device (for example, Patent Documents 2 and 3) that performs measurement is known.

In this case, when measuring the height or level difference in any of the above measuring apparatuses, first, a measuring element is brought into contact with one point (hereinafter referred to as “reference point”) of the object to be measured, or a target mark image. In this case, the measured value in the height direction (hereinafter referred to as the “Z direction”) is recorded, and this is used as a reference value. Hereinafter, the object to be measured is placed in the vertical direction (hereinafter referred to as “X direction”) and the horizontal direction by means of an X, Y stage or the like so that the measuring element or the target mark image is positioned at “measurement point”. (Hereinafter referred to as “Y direction”) and the like, and the difference between the measured value at this point and the reference value is used as the value of the height or step.
JP 2005-214833 A JP 63-8508 A JP-A-10-2221013

  As is apparent from the description of the prior art measuring apparatus, in the prior art, when measuring the dimension of the object to be measured in the Z direction, it is inevitable to move the object to be measured in the plane direction. In this case, when the object to be measured is moved in the plane direction, it is easily assumed that there is a considerable amount of shake in the Z direction, which may remain as an uncertain factor during measurement. Therefore, in order to reduce it as much as possible, efforts to increase the working accuracy of the X, Y stage, etc. were required.

  In addition, since the object to be measured must be moved in the plane direction every time measurement is performed, extra work time is required, which hinders shortening of the measurement time.

  The present invention was created for the purpose of providing a height / level difference measuring apparatus that solves the above-mentioned problems, and is an optical type that performs measurement by detecting the focal point of a target mark image projected on a measurement object. The measuring device is a direct prior art. That is, the height and level difference measuring apparatus of the present invention detects the amount of movement in the Z direction by detecting the focal point of the target mark image projected on the object to be measured that moves relative to the Z direction, and detects the Z of the object to be measured. Wedge type having a pair of wedge parts combined so that the wedge directions are opposite to each other so that the illumination light beam is divided into two in a direction perpendicular to the optical axis and deflected in the opposite direction The prism is arranged in the projection optical system, and a plurality of target marks arranged so as to straddle the two divided light beams are provided on the projection original plate.

  Here, as the second invention, a plurality of types of projection original plates in which a plurality of target marks are provided differently in the first invention are prepared, and the height and step which can be selectively inserted into the projection optical system. A measuring device is also disclosed.

  In the second aspect of the present invention, as means for selectively inserting a plurality of types of prepared projection original plates into the projection optical system, the moving direction of the slide member that can move horizontally in a direction orthogonal to the optical axis of the projection optical system In addition to arranging a plurality of types of projection master plates, a plurality of types of projection master plates may be arranged in the rotation direction of a rotating member having a rotation center at a position offset with respect to the optical axis of the projection optical system. In these cases, it is preferable to arrange a plurality of sets of target mark image projection members composed of a wedge prism and a projection original plate instead of the projection original plate alone.

  According to the present invention, the illumination light beam for projecting the target mark onto the object to be measured is in a direction orthogonal to the optical axis by the wedge-shaped prism having the pair of wedge portions combined so that the wedge directions are opposite to each other. Divided in two, each deflected in the opposite direction. On the other hand, since the target mark is arranged so as to straddle the light beam divided into two parts, the target mark image projected on the object to be measured is shifted with the division line between the target position and the target mark is relatively Even if it is small, the focusing operation can be easily performed.

  In the present invention, a plurality of target marks are provided on the projection original plate because the focusing operation can be easily performed even if the target marks are relatively small. By doing so, as long as the reference location of the object to be measured and the location to be measured match any one of the plurality of target mark images in the field of view, the object to be measured is moved between two points without moving in the plane direction. It becomes possible to measure a dimensional difference. That is, after performing the focusing operation of the target mark image located at the reference position in the field of view by relative movement of the optical system and the object to be measured in the Z direction, the position in the plane direction of the object to be measured remains as it is in the field of view. If the operation of focusing another target mark image located at the location to be measured is performed in the same manner, the amount of movement between them becomes a measured value.

  Further, according to the second invention, a plurality of types of projection original plates with different methods of providing a plurality of target marks are prepared, and these can be selectively inserted into the projection optical system. Accordingly, it is possible to select a projection master plate on which a target mark is appropriately provided, and it is possible to minimize the number of scenes in which the object to be measured must be moved in the plane direction. Depending on the type of electronic parts such as ICs and precision processed parts, the object to be measured can be categorized to a certain extent on the surface irregularities. It is particularly effective to select and prepare seeds.

  When arranging multiple types of projection original plates on the slide member and the rotation member, it is not necessary to arrange a plurality of target mark projection members consisting of a wedge-shaped prism and projection original plate at the time of switching. This is particularly effective for increasing accuracy.

  As described above, according to the optical height / level difference measuring apparatus of the present invention, it is possible to measure the height and level difference without moving the object to be measured in the plane direction, thus enabling high-precision measurement and shortening the measurement time. It becomes possible to do.

  Hereinafter, specific embodiments of the optical height / step measuring apparatus of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing an optical system of this measuring apparatus. In the figure, symbol A is an observation optical system in which a measurer observes the object to be measured for measurement, and the observation light beam of the object to be measured (not shown) on the stage passes through the objective lens 5 and is passed through the beam splitter 4. (A semi-transparent mirror is used here) Reflected and deflected, passes through the tube lens 8, further deflected by the mirror 7, and is measured by the prism 6 with the direction of the eyepiece (not shown) of the measurer and the camera ( (Not shown).

  On the other hand, symbol B in the drawing is a projection optical system for projecting the target mark image onto the object to be measured, and the illumination light beam from the light source 1 passes through the condenser lens 2 to the wedge-shaped prism 11 and the projection original plate 12. After passing, the light passes through the tube lens 3, further passes through the beam splitter 4, and enters the objective lens 5.

  5 and 6 are diagrams for explaining the details and operation of the configuration of the projection optical system B for projecting the target mark image onto the object to be measured. In the measuring apparatus of the present invention, the illumination light beam is divided into two in the direction perpendicular to the optical axis S by the wedge-shaped prism 11 arranged in the projection optical system and deflected in the opposite direction. The wedge-shaped prism 11 is combined so that a pair of wedge portions 11A and 11B formed at an appropriate angle (for example, 2 to 3 °) are opposite to each other, and both surfaces forming the wedge are polished to a flat surface with high accuracy. Has been. In addition, the shape is shown here as a combination of planar semicircular shapes in the left-right direction, but it is of course possible to have other shapes and combinations.

  On the other hand, the target mark arranged on the original plate 12 which is provided to be joined or spaced apart from the wedge-shaped prism 11 is arranged so as to straddle the split line of the light beam divided into two, in other words, the target mark is wedge-shaped. The wedge portions 11 </ b> A and 11 </ b> B of the mold prism are arranged so as to straddle the opposing ridge lines. A plurality of target marks are arranged within the above ridge line range, and are arranged, for example, at several places including one center point or all on the ridge line. (4A) to (4D) in FIG. 4 are diagrams showing examples of the projection original plate 12 in which the target marks are provided in different ways, and the symbol M in the figure indicates the target mark.

  According to the present invention, since the target mark is arranged so as to straddle the light beam divided into two parts, the target mark image projected on the object to be measured is displaced with the dividing line interposed therebetween except for the in-focus position. In the projection optical system of FIGS. 5 to 6, two targets M1 and M2 are arranged on the projection original plate 12, but these target images MM1 and MM2 on the object to be measured 20 are within the same field of view. Therefore, both of the objects to be measured 20 can be visually recognized without moving in the plane direction. Therefore, first, the focusing operation of the target mark image MM1 located at the reference point 20A of the object to be measured 20 is performed by moving the optical system or the stage on which the object to be measured is placed in the Z direction by a coarse / fine movement device (not shown). (See FIG. 5) Then, the position of the object to be measured in the plane direction is kept as it is, and another focusing operation for another target mark image MM2 located at the measurement location 20B in the field of view is performed in the same manner (see FIG. 6). The amount of movement between them detected by the scale (height / step) is sent to the counter as an electrical signal for display and displayed as the height or step of the object to be measured.

  By the way, for example, depending on the type of electronic parts such as ICs and precision-machined parts, the object to be measured can be categorized to some extent on the surface irregularities. Can do. Therefore, if the target mark is suitable for the type of the object to be measured, it is possible to minimize the number of scenes where the object to be measured must be moved in the plane direction. In this embodiment, a plurality of types of projection original plates with different target mark arrangements are prepared on the basis of the premise described above, and these can be selectively inserted into the projection optical system. Here, as a mechanism for this, two sets of target mark image projections consisting of a set of a wedge-shaped prism 11 and a projection original plate 12 are projected in the moving direction of a slide member 10 that can move horizontally in a direction perpendicular to the optical axis S of the projection optical system. The members are arranged, and these are selectively inserted into the projection optical system by a slide operation with the knob 13.

  FIGS. 7 to 8 are views showing examples of different mechanisms for inserting a projection original plate in which a plurality of target marks are provided in different ways into the projection optical system. Here, the optical axis S of the projection optical system is shown. A plurality of sets of target mark image projecting members composed of a set of wedge-shaped prisms 21 and projection original plates 22 are arranged in the rotational direction of the rotating member 20 having the rotation center 23 at a position offset with respect to the position. Are selectively inserted into the projection optical system.

The block diagram which shows the optical system of the optical height and level | step difference measuring apparatus in this invention. FIG. 4 is a cross-sectional view of a wedge-shaped prism and a projection original plate. The top view of a wedge-shaped prism and a projection original plate location as above. The top view which shows the example of a projection original plate same as the above. FIG. 3 is a partially omitted perspective view showing the illumination optical system. FIG. 3 is a partially omitted perspective view showing the illumination optical system. Sectional drawing of the Example from which a wedge-shaped prism differs from a projection original plate location same as the above. The partially cutaway top view of the Example from which a wedge-shaped prism differs from a projection original plate location same as the above.

Explanation of symbols

M target mark 1 light source 11 wedge prism 12 projection original plate

Claims (4)

In a measuring apparatus that detects the amount of movement in the Z direction by detecting the in-focus point of a target mark image projected on the object to be measured that moves relative to the Z direction, and measures the dimension in the Z direction of the object to be measured. A wedge-shaped prism having a pair of wedge parts combined so that the wedge directions are opposite to each other is divided into two in the direction perpendicular to the optical axis and deflected in the opposite direction, and the projection optical system is divided into two An optical height / level difference measuring apparatus comprising a plurality of target marks arranged on a projection original plate so as to straddle the emitted light flux. 2. The optical height / step measuring apparatus according to claim 1, wherein a plurality of projection original plates in which a plurality of target marks are provided are prepared, and these can be selectively inserted into a projection optical system. Select multiple target mark image projection members consisting of a wedge prism and projection master plate in the direction of movement of the slide member that can move horizontally in the direction perpendicular to the optical axis of the projection optical system. 3. The optical height / step measuring apparatus according to claim 2, wherein the optical height / step measuring apparatus is a means for inserting into a projection optical system. By arranging a plurality of target mark image projecting members composed of a wedge prism and a projection original plate in the rotational direction of a rotating member having a rotation center at a position offset with respect to the optical axis of the projection optical system, The optical height / step measuring apparatus according to claim 2, wherein the optical height / step difference measuring device is a means for selectively inserting the light into the projection optical system.

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