Wafer surface inspection apparatus and wafer surface inspection method

Abstract

A wafer surface inspection method and apparatus of high sensitivity, and free from performance degradation in terms of cleanliness, coordinate repeatability of foreign particles and the like. Gas for cooling is sprayed onto a laser irradiation position on the wafer surface to prevent an increase in temperature of the foreign particles and to suppress break-down of the foreign particles.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a surface inspection apparatus and a surface inspection method of a subject to be inspected, and relates for example to a wafer surface inspection apparatus and a wafer surface inspection method for inspecting for foreign particles or foreign matter, defects and the like on a semiconductor wafer surface in a manufacturing process of a semiconductor device.[0002]In a manufacturing process of a semiconductor device, a circuit is formed by transferring a pattern onto a bare wafer and etching the same. In the manufacturing processes of various semiconductor devices during which circuits are formed, foreign particles adherent to the wafer surface, defects and the like become major factors causing a decrease in yield. The foreign particles adherent to the wafer surface and the defects are managed in each manufacturing process, and a wafer surface inspection apparatus detects the foreign particles adherent to the bare wafer ...

AI Technical Summary

Benefits of technology

[0005]For a wafer surface inspection apparatus, high cleanliness and high precision coordinate repeatability of foreign particles are required. The wafer contamination attributable to the destruction of foreign particles, however, would degrade such performance. To address this problem, although the density of energy of laser irradiation may be decreased to avoid destruction of foreign particles, it would lower detection sensitivity as well. Accordingly, there is a demand for a method that can prevent destruction of foreign particles attributable to laser without lowering the detection sensitivity.

[0006]An object of the present invention is to provide a wafer surface inspection apparatus that is highly sensitive and free of degradation of device performance in terms of cleanliness, coordinate repeatability of foreign particles and the like.

[0007]It is considered that foreign particles are broken down (destructed) by irradiation with a laser beam because the temperature of the particles increases due to the irradiation with the laser beam. Thus, by spraying gas for cooling onto the laser irradiation position on the wafer, the increase in temperature of the foreign particles can be prevented to suppress destruction of the foreign particles. The conditions for spraying gas for cooling depend on the density of energy at the point of laser irradiation. That is, when the density of energy is large, it is necessary to increase the flow velocity and the flow rate of the gas for cooling to increase the amount of heat radiation from the foreign particles.

[0010]According to the present invention, irradiation of laser and spraying of gas with respect to the wafer are carried out at the same time and for the same location. This can increase the density of energy of irradiated laser at the limit of not destroying the foreign particles, compared to the conventional case. Accordingly, it is possible to carry out the inspection without destructing the foreign particles, while preventing lowering of detection sensitivity.

Problems solved by technology

However, it has become found that when the foreign particles are made of organic matter prone to break down, the foreign particles may be broken down (destructed) by heat of the laser irradiation, in which case the particles broken down would fly around the area and adhere to the wafer surface to thereby contaminate the wafer.

However, with an increase in sensitivity of detection of foreign particles, laser of high power has come to be used, and thus, the phenomenon of destruction of foreign particles by laser irradiation has begun to emerge.

The wafer contamination attributable to the destruction of foreign particles, however, would degrade such performance.

To address this problem, although the density of energy of laser irradiation may be decreased to avoid destruction of foreign particles, it would lower detection sensitivity as well.

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