In this paper, fabrication of silicon microchannels with integrated obstacles by using 25 wt.% tetramethylammonium hydroxide (TMAH) aqueous solution at the temperature of 80?C is presented and analysed. We studied basic island patterns, which present union of two symmetrical parallelograms with the sides along predetermined crystallographic directions <n10> (2<n<8) and <100>. Acute angles of the parallelograms were smaller than 45?. We have derived analytical relations for determining dimensions of the integrated obstacles. The developed etching technique provides reduction of the distance between the obstacles. Before the experiments, we performed simulations of pattern etching based on the level set method and presented evolution of the etched basic patterns for the predetermined crystallographic directions <n10>. Combination of basic patterns with sides along the <610> and <100> crystallographic directions is used to fabricate a matrix of two row of silicon obstacles in a microchannel. We obtained a good agreement between the experimental results and simulations. Our results enable simple and cost-effective fabrication of various complex microfluidic silicon platforms with integrated obstacles.