In this paper, the authors present the fabrication of high-yield Si thin-membranes by electrochemical etch-stop in tetramethyl ammonium hydroxide (TMAH): isopropyl alcohol (IPA):pyrazine solutions. The current-voltage (I-V) characteristics of n- and p-type Si in TMAH:IPA;pyrazine solutions were analysed, repsectively. Open circuit potential (OCP)and passivation potential (PP) of n- and p-type Si, respectively, were obtained and applied potential was selected between n- and p-type Si PPs. The electrochemical etch-stop method was applied to the fabrication of 801 micro-membranes with 20.0 $mu extrm{m}$ thickness on a 5" Si wafer. The average thickness of fabricated 801 micro-membranes on one wafer 20.03$mu extrm{m}$ and the standard deviation was ${pm}$0.26$mu extrm{m}$. The Si surface of the etch-stopped micro-membranes was extremely flat with no noticeable taper or nonuniformity. The results indicate that use of the electrochemical etch-stop method for the etching of Si in TMAH:IPA;pyrazine solutions provides a powerful and versatile alternative process for fabricating high-yield Si micro-membranes.