Semiconductor structure etching solution and method for fabricating a semiconductor structure using the same etching solution

A method of removing a stripe having a line width smaller than 20 nm in a semiconductor structure, the method comprising:

• forming a sidewall spacer surrounding the stripe;
• preparing an etching solution by applying an ionic strength enhancer to an etchant, wherein the ionic strength enhancer has a molar concentration in a range from about 10−3 M to about 10 M in the etching solution and includes at least one of Li+, Na+, K+, Mg2+, Ca2+, N(CH3)+, and N(C2H5)4+;
• and
• applying an etching solution to the stripe.

A method for silicon removal enhancement during forming a semiconductor structure, comprising:

• combining an ionic strength enhancer, a solvent and an etchant to form an etching solution, wherein the ionic strength enhancer has an ionic strength greater than 10−3 M in the etching solution, the solvent comprising at least one of isopropanol, acetone, acetic acid, ethyl acetate, or super critical carbon dioxide;
• forming at least one silicon stripe with a width narrower than 20 nm;
• covering at least a sidewall of the silicon stripe with a dielectric material;
• and
• applying the etching solution to remove the silicon stripe thereby exposing a sidewall of the dielectric material and forming a trench having an average width substantially similar to a width of the silicon stripe.