JP2512050Y2 - Observation device in non-contact detection device - Google Patents

Description

[Detailed Description of the Invention] <Field of Use> The present invention detects the surface shape / roughness of an object to be measured, pattern edge detection, etc. by an optical non-contact means using laser light and measures the surface of the non-contact detection device. The present invention relates to an observation device.

<Prior Art> The prior art will be described with an example of pattern edge detection of an IC chip or the like.

FIG. 3 shows an optical system based on the astigmatism method, in which light from the laser light source 1 is polarized by the polarization beam splitter 2 and λ / 4.
After passing through the plate 3, the object surface 4 is irradiated with the objective lens 4 and the reflected light is redirected again through the polarization beam splitter 2 at a right angle, divided by the semi-transparent mirror 6 and then split through the cylindrical lenses 7 and 8. The light receiving elements 9 and 10 are adapted to receive the light. Here, the divided light receiving element 9
Is divided into 4 and 10 is divided into 2 so that the control signal for moving the objective lens 4 to adjust the focus at the measurement point is obtained by the 4-division element 9 and the pattern edge detection is performed by the 2-division element 10. ing. Note that this edge detection is to determine the position of a fine pattern line of an IC chip or the like formed on a semiconductor wafer, and the laser spot defines the boundary of the line (which has a certain width in this case) as the edge. When scanning, the reflected light received by the two-divided element is strong on one side and weaker on the other side, so that the edge position of the line is specified from the difference.

In this measurement, the laser light is what irradiates a fine laser spot on the measurement surface, because it is physically difficult to directly observe the irradiation part with a macroscopic microscope interposed, It was not possible to easily know which position on the measurement surface of the entire object to be measured the position of the laser spot irradiated in the unit of μm. In particular, when many lines are arranged in parallel, it is very difficult to detect the detection position. In addition, it is necessary to match the direction of the line with the optical system by the orientation of the measurement surface, but this is a complicated task to detect.

The problem as described above is the same in the surface roughness measuring device, for example, and it has not been possible to easily know exactly which point the detected value is output.

It should be noted that an observation optical system may be provided separately from the detection optical system, but this is not only a structural and device problem, but it also means that the measurement point is inclined and observed. It becomes a malfunction.

<Means for Solving the Present Invention> In view of the problems described above, the present invention provides another light source that irradiates the periphery of the laser spot of the measurement point in addition to the laser light as the light source for detection, and measures the reflected light. By passing through the same optical system as the system and branching it to the observation optical system on the way, the measurement point can be observed (confirmed) with a slight addition of the optical system.

<Examples> FIG. 1 is an example of an optical system based on the astigmatism method, and description of parts common to those in FIG. 3 is omitted.

In the figure, 11 is an observation light source for irradiating the measurement surface 5, and is provided so as to be located around the objective lens 4 or between the objective lens 4 and the measurement surface 5. Reference numeral 12 denotes a light beam branching member, for example, a semitransparent mirror, which is interposed in the optical path between the semitransparent mirror 6 and the cylindrical lens 8 shown in the conventional optical system of FIG. It is reflected to the side of the divided light receiving element 10 and the other part is infrared filter
It is led via 13 to a microscope section 14 as an optical system for observation. Therefore, the microscope unit 14 is in the same optical path as the detection optical system, and the detection laser light and the observation light are incident.

In the illustrated example, the reflected light of the laser light and the observation light radiated on the measurement surface 5 has its optical path changed by the polarization beam splitter 2 and enters the semi-transparent mirror 6, and a part of the light passes through the cylindrical lens 7. Through the divided light receiving element 9 for focus detection
The light is reflected to the side, and the other part is transmitted through the semi-transparent mirror 6 and is incident on the second semi-transparent mirror 12. Part of the incident light on the semi-transparent mirror 12 is reflected and sent to the split light receiving element 10 for displacement detection of the target edge or the like, and the other transmitted light passes through the infrared filter 13 and the microscope unit 14 Sent to.

Therefore, the position of the measurement point on the measurement surface 5 can be easily confirmed and observed with the naked eye from the microscope unit 14.

Next, FIG. 2 shows a case where the present invention is applied to an optical system by the critical angle method, 1 is a laser light source, 22 is a polarization beam splitter, 23 is a λ / 4 plate, 24 is an objective lens, 26
Is a semi-transparent mirror.
The reflected light and transmitted light at the critical angle prisms 27 and 28, respectively.
And is sent to the split light receiving element 29 for focus detection and the split light receiving element 30 for displacement detection.

Therefore, in the present invention, the semi-transparent mirror 12 as a light beam branching member is interposed in the optical path between the semi-transparent mirror 26 and the critical angle prism 28, and a part of the incident light to the semi-transparent mirror 12 is reflected to make the critical angle. The transmitted light is sent to the prism 28, and the other transmitted light is sent to the infrared filter 13 and the microscope section 14 as an optical system for observation which are constructed in the same manner as in the first embodiment.

Therefore, the observation light source 11 disposed near the objective lens 24
The observation light that is emitted from the laser beam and reflected on the measurement surface 5 and passed through the same optical path as the laser light for detection enters the microscope section 14 in the same manner as in the first embodiment, and the position of the measurement point is determined accordingly. You will be able to easily check and observe.

By the way, in any of the above-mentioned embodiments, the focusing in the observing optical system requires a means for cooperating with the focusing means of the laser spot for detection (in this embodiment, the control means by the divided light receiving element). If it is applied, automatic focusing can be achieved. Further, in each of the above-mentioned embodiments, the observation optical system is configured so that macroscopic observation can be performed by the microscope section 14, but instead of this microscope section,
It is also possible to use a monitor TV display system using a CCD camera. In this case, the infrared filter may be set according to the degree of reflection from the object to be measured. Furthermore,
The case where the semi-transparent mirror is provided as the light beam branching member for guiding the observation light to the observation optical system has been described, but it goes without saying that this may be configured by a beam splitter.

<Effect> As described above, according to the present invention, the measurement point on the measurement surface of the DUT is measured in a non-contact manner by the laser beam,
In what is to be detected, the measurement point and its periphery are irradiated with the observation light, and the reflected light is imaged on the observation optical system through the same optical system as the detection light, thereby observing,
Since it can be confirmed, the position or state of the measurement point by the laser spot on the measurement surface can be easily recognized, the measurement position can be searched or set very easily, and its operation is easy, and the optical system It is possible to provide a device having an extremely excellent practical effect.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical system by the astigmatism method according to the first embodiment of the present invention, FIG. 2 is a block diagram of an optical system by the critical angle method according to the second embodiment of the present invention, and FIG. 3 is a configuration diagram of an optical system based on the astigmatism method of FIG. 1: Laser light source, 5: Measurement surface 11: Observation light source, 12: Light flux splitting member 13: Infrared filter 14: Observation optical system (microscope section)

Continuation of front page (56) Reference JP-A-60-253905 (JP, A) JP-A-60-253822 (JP, A) JP-A-60-186705 (JP, A) JP-A-60-179949 (JP , A) JP 60-15939 (JP, A) JP 59-101827 (JP, A) JP 59-100805 (JP, A) JP 59-27207 (JP, A) JP 59-18913 (JP, A) JP-A-56-24504 (JP, A) Actual development 60-21911 (JP, U)

Claims (3)

(57) [Scope of utility model registration request] 1. A non-contact detecting device having an optical system configured to irradiate a measuring surface of an object to be measured with detection light from a laser light source and to perform focusing and displacement detection of a measurement point by the reflected light. An observation light source for illuminating a surface is provided outside the optical system, and a light beam branching member is provided in the optical path of the optical system so that the reflected observation light passing through the same optical system as the detection light is branched and imaged. And an observation device in a non-contact detection device, wherein an observation optical system is provided. 2. An observation device in a non-contact detection device according to claim 1, wherein the observation optical system is a microscope section. 3. An observation device in a non-contact detection device according to claim 1, wherein the observation optical system is a CCD camera.