NOVELTY - Method for making three-dimensional nano-structure (108) array, involves: providing substrate (100); forming mask on surface of substrate, where mask is monolayer nanosphere array or film defining several holes arranged in array; simultaneously tailoring mask and etching substrate by mask; and removing mask.    USE - For making three-dimensional nano-structure array (claimed). The three-dimensional nano-structure array is useful in nano integrated circuits, light-emitting diodes, solar cells, and nano optical components such as plasmonic.    ADVANTAGE - The method provides three-dimensional nano-structure array by low-cost and simple method. The method involves simultaneously tailoring mask and etching substrate by the mask. Because reactive atmosphere can tailor the mask and simultaneously etch substrate by mask, several nanospheres become smaller, holes become greater and gap between adjacent holes becomes smaller i.e. gap between two adjacent nanospheres becomes greater during process; so that more of portion of substrate is etched during step of tailoring and etching. As holes become larger, more of substrate can be etched. Thus, three-dimensional nano-structures with stepped hollow are obtained.    DETAILED DESCRIPTION - Method for making three-dimensional nano-structure array (108), involves: providing substrate (100); forming mask on surface of substrate, where mask is monolayer nanosphere array or film defining several holes arranged in array; simultaneously tailoring mask and etching substrate by mask; and removing mask. The monolayer nanosphere array is formed by preparing nanosphere solution; forming monolayer nanosphere solution on substrate; and drying monolayer nanosphere solution. The forming of monolayer nanosphere solution on substrate involves diluting nanosphere solution; inserting the substrate into diluted nanosphere solution; and drawing substrate out of diluted nanosphere solution. The angle between surface of substrate and level of nanosphere solution is 5-15 degrees . The speed of inserting and drawing substrate is 3-10 ml/hour. Alternatively, the forming monolayer nanosphere solution on substrate involves diluting nanosphere solution to form diluted nanosphere solution; dripping diluted nanosphere solution on surface of substrate; spinning substrate at speed of 400-500 rpm for 5-30 seconds; increasing spinning speed of substrate to 800-1000 rpm for 30 seconds to 2 minutes; and increasing spinning speed of substrate to 1400-1500 rpm for 10-20 seconds. The monolayer nanosphere array is hexagonally close-packed, squarely close-packed, or concentrically close-packed. A step of hydrophilicly treating substrate is performed before forming monolayer nanosphere solution on substrate. The tailoring and etching is performed in reactive atmosphere (110) produced by microwave plasma system. The reactive atmosphere simultaneously tailors monolayer nanosphere array and etches substrate using monolayer nanosphere array as mask. The reactive atmosphere consists of chlorine gas, argon gas, and oxygen gas. The input rate of chlorine gas is 10-60 cm3/minute, input rate of argon gas is 4-20 cm3/minute, and input rate of oxygen gas is 4-20 cm3/minute. The tailoring and etching time in reactive atmosphere is 1-2.5 minutes. The ratio between power of plasma system and working pressure of reactive atmosphere is less than 20:1. The mask is removed by dissolved in stripping agent. The film is made of polymer and is formed by nano-imprint or template deposition.    DESCRIPTION OF DRAWING(S) - The figure shows process for making the three-dimensional nano-structure array.    Substrate (100)    Three-dimensional two-layer cylindrical nano-structures (102)    First cylinder of nano-structure (104)    Second cylinder extending from top of first cylinder (106)    Monolayer nanosphere array (108)    Reactive atmosphere (110)