Microfluidic standard process

The substrate typically is a 100 mm borosilicate glass or fused silica wafer. Our substrates are obtained from carefully selected suppliers and have subnanometer surface roughness.

We apply an etch mask material. Our etch mask has very low pinhole density, and excellent adhesion to glass substrates. A good etch mask is the base of reproducible microchannel fabrication.

Photoresist is spun, exposed through your customised mask and developed. All with micrometer precsion.

The masking material is etched to expose the microfluidic channels.

Channels are isotropically etched in an HF solution. The channel is etched to your specified depth with a uniformity of 1%. Typical channel depth is 10 to 20 microns, but we can go as low as 1 micron and as far as 250 microns. Alternatively channels can be etched by Deep Reactive Ion Etching (DRIE). This allows higher channel density and channels with rectamgular cross sections.

A dry film photoresist is applied on the backside of the wafer. It is a negative tone resist.

The photoresist is illuminated through a second mask which defines the throughholes.

Throughholes are made by powderblasting. Diameter is typically 0.5 to 2 millimeters.

Photoresist and masking material are removed, and wafers thouroughly cleaned.

A cover wafer is fused to the microfluidic wafer by heating to a temperature close to the melting point of the glass. No adhesives or bonding layers are used! We can define electrode patterns in the cover wafer for the purpose of conductivity detectors or heating elements if your application requires so. In that case we use aligned wafer bonding

Finally we dice the wafer into chips of your specified size. Usually we ship chips on bluefoil. Other packages as you specify. Packaging is absolutely dust free and cleanroom compatible.