Laser device with long depth of focus

Abstract

The invention relates to a laser device with long depth of focus, comprising a laser source for emitting single wavelength ultraviolet light, an optical module with a first optical element, a first reflective element and a second reflective element. The first optical element comprises a first surface adjacent to the laser source and a second surface face towards the first surface. At least one of the first and second surfaces is aspherical, so that the UV light having a single wavelength is focused to one point. The first reflective element and the second reflective element are arranged between the laser source and the first optical element. A focal length f1 of the first reflective element and a focal length f2 of the second reflective element have relationships as follow: |f1|+|f2|=d, |f2| / |f1|=2fw / (BGDOF), wherein d represents a distance d spanned by the apexes of the two reflective elements, f represents the focal length of the first optical element, w represents a diameter of a formed light spot, B represents a light beam diameter of the UV light, and GDOF represents a geometrical depth of focus of the laser device.

Description

technical field [0001] The invention relates to a laser device, especially a laser device with a long focal depth. Background technique [0002] With the advancement of semiconductor technology and processing technology, various electronic components and optical components are increasingly miniaturized. Lithography in semiconductor technology, or laser processing in processing technology, have begun to use short-wavelength ultraviolet laser devices (UV Laser) to make the feature size (Feature size) and resolution of electronic components or optical components Resolution meets the requirements. Since the resolution R is inversely proportional to λ / NA (λ is the laser wavelength and NA is the numerical aperture), the DOF (Depth of Focus) is proportional to λ / NA 2 , here it can be understood that the effective depth of laser action is proportional to λ / NA 2 , so as the resolution (as assessed by the laser spot size) increases, the depth of focus decreases. A decrease in the ...

AI Technical Summary

Problems solved by technology

However, this technology requires broadband laser or multi-wavelength laser, resulting in high cost

In addition, Diffractive Optical Element (DOE) can also be used to extend the depth of focus, but this technology still requires broadband laser or multi-wavelength laser, and the high-order diffraction of the beam reduces the light utilization efficiency

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