Rapid soda-lime glass etching process for producing microfluidic channels with higher aspect ratio
Lin C H, Chen K W, Li T Y.
Microsystem technologies, 2014, 20(10-11): 1905-1911.
This paper presents a simple method to produce microﬂuidic channels in soda-lime glasses with the aspect ratio >0.5 utilizing a modifed wet etching protocol. A low-cost positive photoresist (PR) layer is used as the etching mask for the wet etching process. Prior to the PR and primer coating procedure, a UV activation process is adopted for enhancing the binding strength of the hexamethyldisilazane primer layer and the glass substrate, resulting in a better adhesion for the Pr layer. A fast etching recipe is also developed by increasing the acidity and the temperature of the buffered oxide (BOE) etchant. Since the photoresist etching mask does not peel during the etching process shortly, the structure of the etching mask forms a barrier and results in a different diffusion rate for the etchant inside the etched trench structure. A slower etching rate for the glass is observed at the undercut region such that the proposed anisotropic etching pattern can be achieved. Results show that the etching rate of the modifed glass etching process is as high as 7.7 μm/min which is much faster than that of pure BOe etchant (0.96 μm/min). Sealed microﬂuidic channel with the aspect ratio of around 0.62 is produced with the developed method. The method developed in the present study provides a rapid and effcient way to produce microﬂuidic channels with higher aspect ratio.