JPH05223533A - Height measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a height measuring apparatus which can measure the height of a lead correctly in the actual using state while a semiconductor device is mounted on a glass substrate. CONSTITUTION:Laser beams are scanned and condensed onto leads 21 of a semiconductor device 20 mounted on a glass substrate 25. The light reflected at each lead is condensed on a first-dimensional sensor 7 by a first and a second cylindrical lenses 6, 8, with forming an image at a position corresponding to the height of the lead. Nearly the whole of the regularly reflected light from the surface of the glass substrate 25 is cast onto a shielding plate 9. However, the regularly reflected light from an end part of scanning passes aside the shielding plate 9 and forms an image on the first-dimensional sensor 7 corresponding to the height of the upper surface of the glass substrate. The height of each lead from the glass substrate can be correctly measured by a detecting circuit 11 which obtains the height from signals corresponding to the position on the sensor 7 where the image is formed and a correcting circuit 12 which corrects the height using the height signal from the upper surface of the glass substrate as a reference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a height measuring device,
Especially, the lead height of a semiconductor device having a plurality of leads,
That is, the present invention relates to a height measuring device that measures the amount of lead floating from a reference surface.

[0002]

2. Description of the Related Art FIG. 6 is a perspective view showing an example of a conventional height measuring apparatus, and FIG. 7 is an operation explanatory view of the apparatus shown in FIG.

The height measuring device 36 shown in FIG.
1, a light projecting lens 33 that collects the laser light 32 on the lead 21 of the semiconductor element 20, a light receiving lens 34 that collects the reflected light from the lead 21, and a light receiving lens 34 that is arranged at the image forming point of the light receiving lens 34. And a dimension sensor 35.

As shown in FIG. 7, when the height of the lead 21 changes, the reflection points of the laser light 32 change to A, B and C,
Also, the images of the reflection points A, B, and C are
Images are formed on the dimensional sensor at positions A ', B', and C ', respectively. Therefore, the height of one lead can be obtained from the deviation of the image formation point on the one-dimensional sensor 35.

Further, in consideration of the fact that the semiconductor element is placed on a flat substrate for use, a reference plane is obtained from the height of each lead, and the height of each lead from the reference plane is calculated.

The semiconductor element 20 or the height measuring device 36
By moving the leads 21a, 21b, 21
It is possible to measure the height of each lead like c and 21d.

[0007]

In the conventional height measuring device described above, the package portion of the semiconductor element is held by suction or the like, and each lead is measured in a free state without any constraint. Therefore, the reference plane is obtained from the height of each lead, and the actual height is obtained from the reference plane. However, it is important for the height of each lead to be in actual use, that is, the height from the flat substrate when placed on the flat substrate, and the measurement needs to be performed in this state.

When it is attempted to measure the lead height in a practical use state using a conventional height measuring device, it is conceivable that a semiconductor element is placed on a glass substrate and the glass substrate is measured from below. Since the specularly reflected light on the surface is also imaged on the one-dimensional sensor through the light receiving lens, there is a drawback that an accurate height cannot be obtained.

When measuring the lead height of a semiconductor element having a large number of leads, the semiconductor element or
Since the lead height detection device itself must be mechanically moved to measure one point at a time, a moving mechanism such as a stage is required, and time to mechanically move one point at a time is required. There was a drawback that it took time to measure.

[0010]

A height measuring device of the present invention comprises a transparent and flat glass substrate on which an object to be measured is placed, a laser, and a mirror for rotationally scanning a laser beam of the laser in one direction. A projection optical system for irradiating a laser beam on a surface to be measured of the object to be measured from obliquely below the glass substrate, and A first cylindrical lens having one focus on the measurement surface and having a curvature in the scanning direction of the laser light, and a partial scanning region of the laser light arranged immediately before the other focus of the first cylindrical lens. Except for the light-shielding plate that blocks the specularly reflected light from the upper surface of the glass substrate, the specularly-reflected light from the glass substrate upper surface and the laser light from the surface to be measured in the partial scanning region disposed immediately after the light-shielding plate. Rebellion A one-dimensional sensor that receives a portion of the light that spreads outside the light shielding plate, and an image of a reflection point of the laser light on the measured surface that has a curvature that is orthogonal to the direction of the curvature of the first cylindrical lens. A light receiving optical system including a second cylindrical lens that forms an image on the one-dimensional sensor, a height measuring circuit that measures the height of the surface to be measured from the output of the one-dimensional sensor, and a height measuring circuit from the upper surface of the glass substrate. And a height correction circuit that uses an output value of the one-dimensional sensor as a reference value in a region where specular reflection light is not blocked by the light shielding plate.

The height measuring apparatus according to the present invention has a transparent flat glass substrate on which an object to be measured is placed, on which a diffusely reflecting substance is attached on a part of the upper surface thereof, a laser, and a laser beam of the laser is rotationally scanned in one direction. A mirror and a lens that scans and condenses the laser light that is rotationally scanned by the mirror in substantially parallel,
A projecting optical system that irradiates a measured surface of the measured object with laser light obliquely from below the glass substrate; and a first projection having one focus on the measured surface and having a curvature in a scanning direction of the laser light. Cylindrical lens, a light shielding plate arranged at the other focal point of the first cylindrical lens to block specularly reflected light from the upper surface of the glass substrate, and the measured surface and the irregular reflection arranged immediately after the light shielding plate. A one-dimensional sensor that receives the diffused light of the laser light from the substance that spreads to the outside of the light shielding plate, and a laser light having a curvature that is orthogonal to the curvature direction of the first cylindrical lens. A light receiving optical system including a second cylindrical lens for forming an image of the reflection point of the image on the one-dimensional sensor, and a height measuring circuit for measuring the height of the surface to be measured from the output of the one-dimensional sensor, Previous And a height compensation circuit as a reference value an output value of the one-dimensional sensor from diffuse reflection material.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention. 2 and 3 are operation explanatory diagrams of the embodiment shown in FIG.

The height measuring apparatus shown in FIG. 1 has a transparent and flat glass substrate 25 on which a semiconductor element 20 as an object to be measured is placed.
A laser 1, a galvano mirror 3 for rotating and scanning the laser light 2 in one direction, and a telecentric projection lens 4 for scanning and condensing the laser light 2 in a substantially parallel manner. Semiconductor element 20 which is the surface to be measured
The projection optical system 5 for irradiating the lead 21 with the laser light 2 obliquely, and the reflected light from the surface to be measured of the laser light 2 is received and has one focus on the surface to be measured. The first cylindrical lens 6 having a curvature and the glass substrate 25, which is arranged immediately in front of the other focus of the first cylindrical lens 6 except for a part of the end of the scanning region of the laser beam 2.
Of the specularly reflected light 15 from the upper surface of the glass substrate 25, the specularly reflected light 15 from the upper surface of the glass substrate 25 at a part of the end of the scanning region which is arranged immediately after the shading plate 9, and the leads 21.
The one-dimensional sensor 7 for receiving the portion of the diffused reflected light 16 from the outside of the light-shielding plate 9 and the curvature of the first cylindrical lens 6 that is orthogonal to the curvature direction, and the image of the reflection point of the lead 21 is formed. The light receiving optical system 10 including the second cylindrical lens 8 that forms an image on the one-dimensional sensor 7, the height measuring circuit 11 that measures the height of the lead 21 from the output of the one-dimensional sensor 7, and the glass substrate 25 Specular reflection light from the upper surface 1
The height correction circuit 12 corrects the measurement result of the height measurement circuit 11 with the output value of the one-dimensional sensor 7 when 5 is received as a reference value. The height correction circuit 12 is composed of a memory unit for storing a reference value and a comparison circuit for comparing the data in the memory.

Next, the operation of this embodiment will be described with reference to FIGS.

The laser beam 2 emitted from the laser 1 is rotationally scanned in one direction by the galvanometer mirror 3, but is substantially parallel scanned by the projection lens 4 of the telecentric system and is held on the glass substrate 25. Semiconductor element 2
The lead 21 of 0 is focused and irradiated. At this time, part of the laser light 2 is specularly reflected by the surface of the glass substrate 25. The laser light 2 that has passed through the glass substrate 25 is reflected by the surface of the lead 21, but since the surface of the lead 21 is somewhat rough, diffuse reflection also occurs. The divergence angle of the beam is larger for the reflected light 16 on the leads 21.

The reflected light will be described below separately in the scanning direction and the direction perpendicular to the scanning.

First, considering only the scanning direction, FIG.
As shown in, the second cylindrical lens 8 can be considered as a simple glass plate. The specular reflection light 15 on the glass surface at each scanning position has its optical axes substantially parallel,
Further, although it diffuses with a certain divergence angle, the beam of each specularly reflected light 15 becomes substantially parallel light and the optical axis is bent by the action of the first cylindrical lens 6, and it tries to gather at the focal position. Since the light shielding plate 9 is arranged before the focal position, the light 1 specularly reflected at the edge of the scanning region 1
A part of 5 ′ passes through the light shielding plate 9 and is applied to the one-dimensional sensor 7. However, the specularly reflected light 15 in the other scanning region is collected on the light shielding plate 9 and is then projected onto the one-dimensional sensor 7. Not irradiated.

On the other hand, since the diffused reflection light 16 on the lead 21 has a larger beam divergence angle than the regular reflection light 15 on the glass surface, the beam diameter after passing through the first cylindrical lens 6 also becomes large, and the light shield plate Although a part is blocked by 9, the remaining part is irradiated on the one-dimensional sensor 7 arranged in the rear (FIG. 2).

Next, considering the direction perpendicular to the scanning,
The first cylindrical lens 6 can be considered as a simple glass plate. Therefore, the spot condensed on the lead 21 is changed by the second cylindrical lens 8.
An image is formed on the one-dimensional sensor 7. Here, if the height of the lead 21 changes, the image forming position on the one-dimensional sensor 7 changes,
This change can be detected by the one-dimensional sensor 7 (FIG. 3), and the height of the lead 21 can be obtained.

At the end of the scanning area, the reflected light 15 'from the upper surface of the glass substrate 25 passes through the light shielding plate 9 and is applied to the one-dimensional sensor 7, whereby the upper surface of the glass substrate 25 is exposed. You can ask for height. Further, the specularly reflected light 15 from the lower surface of the glass substrate 25 is generally outside the measurement range of the one-dimensional sensor 7 because the glass substrate 25 is thicker than the measurement range and can be ignored. The output value of the one-dimensional sensor 7 at the end of the scanning area is taken in as a reference value of the height correction circuit 12, and the height data obtained by the height detection circuit 11 is corrected by this reference value.

As described above, due to the function of the pair of cylindrical lenses and the light blocking plate, in the normal scanning area, the reflected light from the glass surface is blocked and the reflected light from the leads is efficiently collected on the one-dimensional sensor. While measuring the lead height,
At the end of the scanning region, specular reflection light on the glass upper surface is collected on the one-dimensional sensor and the height of the glass upper surface is measured, so that the height of the lead from the glass upper surface can be accurately measured.

Further, since the laser beam can be scanned at high speed by the galvano mirror and the reflected light can be collected on the one-dimensional sensor, the height of each lead can be measured at high speed.

FIG. 4 is a perspective view showing another embodiment of the present invention. FIG. 5 is an operation explanatory diagram of the embodiment shown in FIG.

In FIG. 4, the projection optical system 5 is the same as that shown in FIG. A diffuse reflection material 26 is attached to the peripheral portion of the upper surface of a transparent and flat glass substrate 25 on which the semiconductor element 20 as the object to be measured is placed. The light receiving optical system 10 receives the reflected light of the laser light 2 from the surface to be measured, has one focus on the surface to be measured, and has a first cylindrical lens 6 having a curvature in the scanning direction of the laser light; A light shielding plate 9 arranged at the other focal point of the cylindrical lens 6 and blocking the specularly reflected light 15 from the upper surface of the glass substrate 25, and a light shielding plate 9 arranged immediately after the light shielding plate 9 to diffusely reflect light 16 from the lead 21 and the irregular reflection substance 26. , 16 'of the one-dimensional sensor 7 for receiving the portion of the light-shielding plate 9 spread outside the light-shielding plate 9, and the first cylindrical lens 6
The second cylindrical lens 8 has a curvature that is orthogonal to the direction of the curvature of, and forms an image of the reflection point of the lead 21 and the diffuse reflection material 26 on the one-dimensional sensor 7. The height measuring circuit 11 measures the height of the lead and the height of the diffuse reflection material from the output of the one-dimensional sensor 7. The height correction circuit 12 corrects the height of the lead with the height of the diffuse reflection material 26, that is, the height of the upper surface of the glass substrate 25 as a reference value. The height correction circuit 12 is composed of a memory unit for storing a reference value and a comparison circuit for comparing the data in the memory.

Next, the operation of this embodiment will be described with reference to FIG.

First, considering only the scanning direction, FIG.
As shown in, the second cylindrical lens 8 can be considered as a simple glass plate. The specular reflection light 15 on the glass surface at each scanning position has its optical axes substantially parallel,
Although it diffuses with a certain divergence angle, the beam of each specularly reflected light 15 becomes substantially parallel light and the optical axis is bent by the action of the first cylindrical lens 6, and the beams are gathered at the focal position. Since the light shielding plate 9 is arranged at the focal position, the specularly reflected light 15 is collected on the light shielding plate 9 and is not irradiated onto the one-dimensional sensor 7.

On the other hand, the diffusely reflected light 16 and 16 'from the lead 21 and the diffusely reflective material 26 are specularly reflected light 15 from the glass surface.
Since the beam divergence angle is larger than that of, the beam diameter after passing through the first cylindrical lens 6 is also large, and although part of the beam is blocked by the light blocking plate 9, it is arranged at the rear.
It is irradiated onto the dimension sensor 7. (Fig. 5).

Next, considering the direction perpendicular to the scanning,
The first cylindrical lens 6 is the same as that shown in FIG.
Can be thought of as just a glass plate. Therefore,
The spot condensed on the lead 21 is imaged on the one-dimensional sensor 7 by the second cylindrical lens 8. Here, if the height of the lead 21 changes, the imaging position on the one-dimensional sensor 7 changes, and this change can be detected by the one-dimensional sensor 7, and the height of the lead 21 can be obtained. Similarly, the height of the diffuse reflection material 26, that is, the height of the upper surface of the glass substrate 25 can be detected.
The output value of the one-dimensional sensor 7 at this time is taken in as a reference value of the height correction circuit 12, and the height data obtained by the height detection circuit 11 is compared and corrected.

The diffuse reflection material 26 is easily provided by applying a paint or the like on the surface of the glass substrate.

As described above, the function of the pair of cylindrical lenses and the light blocking plate blocks the reflected light from the glass surface, and the reflected light from the leads is efficiently collected on the one-dimensional sensor to measure the lead height. At the end of the scan area,
Since the height of the glass upper surface can be measured by the diffuse reflection material provided on the glass upper surface, the height of the lead from the glass upper surface can be accurately measured.

[0032]

According to the height measuring apparatus of the present invention, instead of placing the object to be measured or the measuring apparatus on the stage and mechanically moving it in order to measure the heights of a large number of leads, the laser light is emitted at high speed. While scanning and irradiating each lead, a set of cylindrical lenses and a light blocking plate work to block the specularly reflected light from the glass surface on which the semiconductor element is mounted and to efficiently reflect the reflected light from each lead on the sensor. The lead height can be measured by collecting the light on the glass substrate at the edge of the scanning area, and the height of the glass upper surface can be measured by specular reflection light on the glass top surface or diffuse reflection light from the diffuse reflection material. The effect is that the height of each lead from the glass substrate can be measured accurately and at high speed in the mounted actual use state.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a diagram showing an optical path on a surface in the scanning direction for explaining the operation of the embodiment shown in FIG.

FIG. 3 is a diagram showing an optical path on a surface in a direction perpendicular to scanning for explaining the operation of the embodiment shown in FIG.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation of the embodiment shown in FIG.

FIG. 6 is a perspective view showing a conventional height measuring device.

FIG. 7 is a diagram for explaining the operation of the conventional height measuring device shown in FIG.

[Explanation of symbols]

 1,31 laser 2,32 laser light 3 galvano mirror 4,33 light projecting lens 5 light projecting optical system 6 first cylindrical lens 7,35 one-dimensional sensor 8 second cylindrical lens 9 light shielding plate 10 light receiving optical system 11 high Measurement circuit 12 Height correction circuit 15 Regularly reflected light on the glass surface 16 Reflected light from the lead 16 'Reflected light from the diffusely-reflecting substance 20 Semiconductor element 21 Lead 25 Glass substrate 26 Diffuse-reflecting substance

Claims (2)

[Claims] 1. A transparent and flat glass substrate on which an object to be measured is placed, a laser, a mirror for rotationally scanning a laser beam of this laser in one direction, and a laser beam rotationally scanned by this mirror is scanned substantially in parallel. A condensing lens, a projection optical system for irradiating the measured surface of the object to be measured with laser light from obliquely below the glass substrate, and the measured surface having one focus, A first cylindrical lens having a curvature in the scanning direction, and a specular reflection light from the upper surface of the glass substrate, except for a partial scanning region of the laser light, which is arranged immediately before the other focal point of the first cylindrical lens. A light-blocking plate for blocking, and a part of the specularly-reflected light from the upper surface of the glass substrate in the partial scanning region, which is arranged immediately after the light-blocking plate, and the diffused light of the laser beam from the surface to be measured, which spreads outside the light-blocking plate To A one-dimensional sensor that emits light and a second cylindrical lens that has a curvature orthogonal to the direction of curvature of the first cylindrical lens and forms an image of a reflection point of the laser light on the surface to be measured on the one-dimensional sensor. A light receiving optical system including a lens, a height measuring circuit that measures the height of the surface to be measured from the output of the one-dimensional sensor, and a region in which regular reflection light from the upper surface of the glass substrate is not blocked by the light shielding plate. A height measuring device comprising a height correction circuit using an output value of the one-dimensional sensor as a reference value. 2. A transparent and flat glass substrate on which an object to be measured is placed, with a diffusely reflecting substance attached to a part of its upper surface, a laser, a mirror for rotationally scanning the laser light of this laser in one direction, and rotation by this mirror. A projection optical system configured to irradiate a laser beam onto a measured surface of the object to be measured from obliquely below the glass substrate, and a lens to condense the scanned laser light in a substantially parallel manner, and to the measured surface. A first cylindrical lens having one focus and having a curvature in the scanning direction of the laser light, and a light shield arranged at the other focus of the first cylindrical lens to block specular reflection light from the upper surface of the glass substrate. A board,
A one-dimensional sensor disposed immediately after the light shield plate for receiving the portion of the diffused reflected light of the laser light from the surface to be measured and the irregular reflection material that spreads outside the light shield plate, and the curvature of the first cylindrical lens. From the output of the one-dimensional sensor, a light receiving optical system including a second cylindrical lens that has a curvature orthogonal to the direction and forms an image of the reflection point of the laser light on the measured surface on the one-dimensional sensor. A height measuring device comprising: a height measuring circuit for measuring the height of a surface to be measured; and a height correcting circuit using an output value of a one-dimensional sensor from the diffuse reflection material as a reference value.