Master mold manufacturing method and mold structure manufacturing method

Abstract

Disclosed is a method of manufacturing a master mold having an uneven pattern which includes wide and narrow concave portions using a reactive ion etching process. The method is capable of manufacturing a master mold improved in the uniformity of concave portions of the uneven pattern by performing a main etching step in which etching is performed, using an original plate which includes a processing target layer and a foundation layer, on the processing target layer using the foundation layer as an etch stop layer and an extra etching step in which etching is performed on the original plate degraded by the main etching step in the uniformity of concave portions in order to improve the uniformity using an etching gas which includes a first gas capable of etching the foundation layer and producing a deposit with a bias power of not greater than 15 W.

1 . A master mold manufacturing method using an original plate which includes a processing target layer and a foundation layer in which a coating layer having an opening pattern constituted by a plurality of openings is formed on the processing target layer and an etching step is performed with a reactive ion etching process using the coating layer as a mask to manufacture a master mold having thereon an uneven pattern corresponding to the opening pattern, wherein:
 the opening pattern comprises a wide opening having a wide width and a narrow opening having a width narrower than the width of the wide opening; and   the etching step comprises:
 a main etching step in which etching is performed on the processing target layer using the foundation layer as an etch stop layer; and 
 an extra etching step in which etching is performed on the original plate, in which a wide bottom surface of a wide concave portion corresponding to the wide opening has been shaped in an upward convex and a narrow concave portion corresponding to the narrow opening has been etched to a depth deeper than a depth of the wide concave portion by the main etching step, such that the wide bottom surface is flattened out and the depth of the wide concave portion corresponds to the depth of the narrow concave portion using an etching gas which includes a first gas capable of etching the foundation layer and producing a deposit with a bias power of not greater than 15 W. 
   
     
     
         2 . The master mold manufacturing method of  claim 1 , wherein the etching gas further comprises a second gas having a greater capability to etch the foundation layer than the capability of the first gas and producing no deposit. 
     
     
         3 . The master mold manufacturing method of  claim 2 , wherein the extra etching step is performed under a pressure of 1 to 12 Pa. 
     
     
         4 . The master mold manufacturing method of  claim 3 , wherein the extra etching step is performed using a diluent gas, as well as the etching gas, with an antenna power of 20 to 200 W. 
     
     
         5 . The master mold manufacturing method of  claim 4 , wherein the reactive ion etching process is an etching process which uses an inductively coupled plasma generation method, a capacitively coupled plasma generation method, or an electron cyclotron resonance plasma generation method, and is capable of independently controlling the bias power and the antenna power. 
     
     
         6 . The master mold manufacturing method of  claim 5 , wherein:
 the reactive ion etching process is an etching process which uses the inductively coupled plasma generation method;   the processing target layer consists primarily of SiO 2  and the foundation layer consists primarily of Si; and   the extra etching step is performed under a flow ratio of 1:1 to 15:1 between the first gas and the second gas and a flow ratio of 1:1 to 1:20 between the etching gas and the diluent gas.   
     
     
         7 . The master mold manufacturing method of  claim 6 , wherein the extra etching step is performed under a flow ratio of 3:1 to 8:1 between the first gas and the second gas, a flow ratio of 1:5 to 1:15 between the etching gas and the diluent gas, a pressure of 4 to 8 Pa, and an antenna power of 30 to 100 W. 
     
     
         8 . The master mold manufacturing method of  claim 4 , wherein the first gas is at least one type of gas selected from the group consisting of CF4, CH2F2, CH3F, C4F8, C4F6, and C5F8, and the second gas is SF6. 
     
     
         9 . The master mold manufacturing method of  claim 4 , wherein the first gas is CH3F, the second gas is SF6, and the diluent gas is Ar. 
     
     
         10 . A mold structure manufacturing method comprising the steps of:
 forming, through electroforming of a metal material, a metal substrate made of the metal material on the uneven pattern of a master mold manufactured by the master mold manufacturing method of  claim 1 ; and   detaching the metal substrate from the master mold to obtain a mold structure, which is the metal substrate, having an uneven pattern reverse to the uneven pattern of the master mold.