JPH0320649A - Photomask inspecting apparatus - Google Patents

Abstract

PURPOSE:To simultaneously perform pattern comparing inspection and surface foreign matter inspection by providing a laser beam reflecting part and a scattering beam detecting part. CONSTITUTION:The laser beam emitted from a laser source 6 irradiates a photomask 7 at a certain angle. The reflected beam thereof is detected at the same angle by a beam detection part 8 and the height of an optical system 1 is adjusted to a place where the intensity of the reflected beam is high to match the focus of the optical system 1. Next, the scattering beam of the laser beam applied to the photomask 7 is detected by a scattering beam detecting part 9. Herein, since the scattering beam from foreign matter becomes reverse to the laser beam from the laser source 6 in phase, a polarizing filter is provided to the detecting part 9 so that only beam changed in its phase by 90 deg. from the phase of the laser beam 6 is detected. The scattering beam scattered from the foreign matter is detected by the detecting part 9 and optical data where intensity is high is stored in a memory buffer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inspection apparatus for photomasks used in the manufacture of semiconductor devices.

2. Description of the Related Art When manufacturing semiconductor devices, in order to expose a predetermined device structure or pattern on a semiconductor substrate, the pattern is enlarged 1 to 10 times and formed on a glass substrate on which a metal such as chromium (CI) is vapor-deposited. A photomask is used. Defects in the photomask and foreign matter on the photomask are transferred onto the semiconductor substrate, which greatly affects the reduction in semiconductor device yield. Regarding this photomask defect inspection, when inspecting a photomask in which multiple main body patterns forming a predetermined integrated circuit are arranged, or a memory pattern with many repeated patterns even in a single arrangement, the adjacent patterns are converted into electrical signals. There is a method of testing for differences (hereinafter referred to as pattern comparison testing).

FIG. 2 shows a schematic diagram of the pattern comparison inspection apparatus described above. Adjacent patterns on the photomask 7 are converted into comparison data D by the optical conversion device 2 via the optical system 1.

In order to focus the optical system, the laser light emitted from the laser source 6 is irradiated onto the photomanuk 7, the reflected light is received by the light receiving part 8, and the height of the optical system 1 is set at the point where the intensity of the reflected light is maximum. This is done by making adjustments. The comparison data D of the actual pattern is compared by the comparing section 3, and only when there is a difference, the comparison information is stored in the defective pattern memory 4 and outputted to the external output 6 to confirm the pattern of the defective part.

Problems to be Solved by the Invention However, with conventional inspection equipment, it is necessary for the operator to distinguish between dust attached to the photomask 7 and the remaining portion of the Dr on the photomask, and it is not possible to check dust on the Cr pattern on the casing. The problem was that it was possible.

The present invention solves the above-mentioned problems and aims to simultaneously perform pattern comparison inspection and surface foreign matter inspection.

Means for Solving the Problem f To achieve this object, the No. 1 Manuk inspection device according to the present invention is provided with a reflected light receiving section for laser light for focusing in pattern comparison inspection. It has a light receiving section for scattered light.

By using the inspection apparatus having the above structure, the laser beam irradiated onto the photomask is focused based on the intensity of the reflected light, and foreign matter is detected based on the intensity of the scattered light.

In this way, the pattern comparison inspection and the surface foreign matter inspection are performed in parallel.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an outline of a photomask inspection apparatus according to the present invention. Furthermore, Figure V? ：'1 is the optical system, 2 is the photoelectric conversion section,
3 a comparison section, 4 a defective pattern list, and 6 an external output, which are the same in structure as the conventional pattern comparison inspection machine. A is a photomask, 61d laser source, 8 is a reflected light receiver that receives l,/- laser reflected light from the photomask, and 9 is a scattered light that receives laser scattered light from F, ti-manuk. This is the light receiving section.

The mechanism of the photomask inspection apparatus of this embodiment constructed as described above will be explained below. 1zu laser source 6
Laser light generated from the photomask 7 is irradiated at a certain angle. The reflected light is applied by the light receiving section 8 at the same angle, and the height of the optical system 1 is adjusted and focused so that the reflected light is located at a position where the intensity of the reflected light is strong. Scattered light of the laser light irradiated onto the photomask is received by the scattered light receiver 9. Since the phase of the scattered light from the foreign object is opposite to that of the laser light from the laser source, the light receiving section 9 has a polarization finoreta so as to receive only the light whose phase has changed by 90' from that of the laser source. Scattered light scattered by a foreign object is received by a scattered light receiver 9, and light data where the intensity is strong is stored in a memory buffer 4.

Effects of the Invention As described above, according to the present invention, a laser beam installed for focusing a photomask is irradiated at an arbitrary angle, and the surface foreign matter on a photomask can be inspected by receiving the scattered light. can. In this way, pattern comparison inspection and surface foreign matter inspection are performed simultaneously, and it is possible to classify missing patterns, Cr residue, foreign matter on the glass surface, and foreign matter on the Cr surface.

1. In the case of the present invention, since the foreign object inspection section can confirm whether the signal 3 recognized as an extra pattern by the pattern comparison section is Cr residue or a foreign object, accurate classification can be achieved in the case of an automatic defect classification device. This method greatly helps in shortening the inspection time.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a pattern comparison button and surface foreign matter detection photomask inspection device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional pattern comparison photomask inspection device. 1...Optical system, 2...Photoelectric conversion section, 3
... Comparison section, 4 ... Memory buffer, 5 ... External output, 6 ... Laser source,
End: Photomask, 8: Reflected light receiver, 9: Scattered light receiver.

Claims (1)

[Claims] A photomask inspection device characterized by comprising a light receiving section for reflected laser light and scattered light.