Photoresist Inspection with the Keyence VHX Microscope Series

NIGHTSEA offers solutions for inspecting photoresist with the Keyence VHX series of digital microscopes. The photoresist used in electronics manufacturing is designed to react when exposed to light in the ultraviolet and blue parts of the spectrum. Once the resist is applied the materials are only handled in rooms in which these wavelength ranges are absent (typically yellow light). Microscopic inspection of the photoresist layers must similarly be done with light sources that will not cause premature exposure. 

Our line of fluorescence adapters for Keyence microscopes provides an opportunity for us to also offer solutions for photoresist inspection tailored to the most commonly used lenses. Note that the solutions are specific to the lenses and not to the microscope model (e.g. VHX-6000, -7000, etc.).

VHX-7100 Fully Integrated (FI) Head 

We designed a custom filter insert that 
slips into the polarization slot on the left 
side (as you are facing the microscope) of the FI head. This removes the shorter wavelengths from the built-in Keyence light source. The image on the left below shows the filter insert. The graph shows the spectral output of the light before (blue line) and after (orange line) inserting the NIGHTSEA filter.

VH-Z00 / VH-Z20 / VH-Z50

With the VH-Z00, VH-Z20 and VH-Z50 there is no provision to replace the Keyence light source with our excitation sources. For fluorescence our light source is placed to the side of the microscope and a barrier filter is placed beneath the lens, as shown in the photograph below. For fluorescence the Keyence light source would be turned off. If the Keyence light source is operated with a barrier filter in place the light has to pass through that filter to reach the subject. Use of an appropriate barrier filter removes UV and blue wavelengths. For photoresist inspection we recommend the Cyan (CY) barrier filter, which is a longpass filter with cutoff at around 550nm. This would be all you need to safely inspect photoresist with these lenses. 

Click here to order the Cyan barrier filter SFA-KZB-BF-CY [ADD LINK]

VH-ZST / VH-Z100 / VH-Z500

With the VH-ZST, VH-Z100, and VH-Z500 there is no provision to introduce a filter in the light path after the Keyence light source as there is with the FI head. For fluorescence applications NIGHTSEA developed adapters that enable the user to mount our excitation light heads in place of the Keyence fiber optic source on these lenses. In this way the excitation light is channeled through the Keyence optics to illuminate the sample from above. We offer an amber LED light source that takes advantage of this adapter to illuminate the sample with light that contains no UV or blue wavelengths. 

There are two scenarios for adding the photoresist illumination capability to Keyence microscopes with these lenses: 

Scenario 1 – You already own a NIGHTSEA system for fluorescence work with one of these lenses. You only need to purchase the amber light head.

Scenario 2 – You do not own any NIGHTSEA equipment You will need: 

• lamp base with power supply
• lens-specific mount
• light head
• light head cable (for operating the light head remote from the lamp base)