PURPOSE: To manufacture a quantum box having a shape-independing upon any plane orientation by a method wherein the droplet of In or Ga is formed, aluminum fluoride is formed, only a region covered with the droplet is etched selectively through dry etching, and a columnar or conical hole is formed.

CONSTITUTION: An AlGaAs substrate 3 is irradiated with Ga molecular beams in a molecular-beam epitaxy device, thus shaping a Ga droplet 14. The AlGaAs substrate 3, on which a droplet adheres, is transferred to a reactive ion-beam etching (RIBE) device. When NF 3 plasma is generated and F atoms are made to reach the AlGaAs substrate 3 at that time, aluminum fluoride is formed on a surface section not covered with the Ga droplet 4. Consequently, RIBE by chlorine is conducted to the substrate 3 with the Ga droplet formed and aluminum fluoride forming layer 2, thus preparing a conical hole 1. Accordingly, a quantum box having a shape independing upon any plane orientation can be manufactured.