Manufacturing method of silicon device

A method of manufacturing a silicon device comprising:

• forming etching start patterns at a surface of a silicon substrate;
• etching said silicon substrate by applying a voltage to said silicon substrate while said silicon substrate is immersed in a solution containing fluorine ions, with said silicon substrate used a positive electrode, to form narrow etched portions extending into said silicon substrate from said etching start patterns;
• accelerating etching of said silicon substrate by increasing current flowing through said silicon substrate after said narrow etched portions have reached a threshold depth in said silicon substrate, to form wide etched portions, wider than said narrow etched portions, at a location deeper than the threshold depth;
• and
• forming a hollow passage in said silicon substrate by filling said narrow etched portions after said wide etched portions have reached a second threshold depth.

A method of manufacturing a silicon device comprising:

• forming etching start patterns at a surface of a silicon substrate;
• etching said silicon substrate by applying a voltage to said silicon substrate while said silicon substrate is immersed in a solution containing fluorine ions, with said silicon substrate used a positive electrode, to form etched portions extending into said silicon substrate from said etching start patterns;
• and
• accelerating etching of said silicon substrate by increasing current flowing through said silicon substrate by changing the voltage applied to said silicon substrate, after said etched portions have reached a threshold depth in said silicon substrate, to form a free standing structure, including a part of said silicon substrate, in which neighboring etched portions are in communication with each other at a location deeper than the threshold depth.