Method, apparatus and program for manufacturing silicon structure

1. A method for manufacturing a silicon structure, the method comprising, in a process of etching a silicon region in a substrate provided with an etch stop layer with use of plasmas generated by alternately supplying an etching gas and an organic deposit forming gas, to thereby form a first opening and a second opening in the silicon region, the second opening being smaller in width than the first opening, the method comprising the steps of:

etching a portion in the silicon region at a highest etching rate under a high-rate etching condition such that the portion does not reach the etch stop layer;

subsequently etching under a transition etching condition in which an etching rate is decreased with time-dependently from the highest etching rate in the high-rate etching condition; and

thereafter, etching the silicon region under a low-rate etching condition of a lowest etching rate in the transition etching condition until the second opening reaches the etch stop layer.

2. The method for manufacturing a silicon structure according to claim 1 , wherein in the transition etching condition, the etching rate is decreased substantially linearly.

3. A recording medium having a manufacturing program being stored thereon, the manufacturing program comprising, in a process of etching a silicon region in a substrate provided with an etch stop layer with use of plasmas generated by alternately supplying an etching gas and an organic deposit forming gas, to thereby form a first opening and a second opening in the silicon region, the second opening being smaller in width than the first opening, the manufacturing program, when executed by a computer, causing the computer to perform the steps of:

control etching of a portion in the silicon region at a highest etching rate under a high-rate etching condition such that the portion does not reach the etch stop layer;

control subsequent etching under a transition etching condition in which an etching rate is decreased with time from the highest etching rate in the high-rate etching condition; and

thereafter, control etching the silicon region under a low-rate etching condition of a lowest etching rate in the transition etching condition until the second opening reaches the etch stop layer.

4. An apparatus for manufacturing a silicon structure, comprising:

a control unit in which is stored a program comprising, in a process of etching a silicon region in a substrate provided with an etch stop layer with use of plasmas generated by alternately supplying an etching gas and an organic deposit forming gas, to thereby form a first opening and a second opening in the silicon region, the second opening being smaller in width than the first opening, the program, when executed by the control unit, causing the control unit to perform the steps of:

control etching of a portion in the silicon region at a highest etching rate under a high-rate etching condition such that the portion does not reach the etch stop layer;

control subsequent etching under a transition etching condition in which an etching rate is decreased with time from the highest etching rate in the high-rate etching condition; and

thereafter, control etching of the silicon region under a low-rate etching condition of a lowest etching rate in the transition etching condition until the second opening reaches the etch stop layer.

5. An apparatus for manufacturing a silicon structure, comprising:

a control unit which uses the recording medium of claim 3 for controlling the apparatus for manufacturing a silicon structure.

6. The method according to claim 1 , wherein the low-rate etching results in etching of the second opening down to the etch stop layer, while at a same time causing little if any excess etching of the first opening that has been previously etched down to the etch stop layer.