Etching method and etching apparatus

• US 8,070,972 B2
• Filed: 03/29/2007
• Issued: 12/06/2011
• Est. Priority Date: 03/30/2006
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Tsujimoto, Hiroshi
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US11/730,196
• Publication Number:
  US 20070284335A1
• Time in Patent Office: 1,713 Days
• Field of Search: None
• US Class Current: 216/41
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks

Abstract

The present invention relates to an etching method for etching a film to form a concave portion therein with the use of a photoresist mask provided with an opening. In this method, there is determined, in advance, a first correlation between a parameter value and an opening dimension of the concave portion, as a process parameter for the etching process, when the etching process is conducted with the use of the mask provided with the opening of a reference opening dimension. In addition, there is determined, in advance, a second correlation between a variation in opening dimension of the mask and a variation in opening dimension of the concave portion. When conducting the etching process, an actual opening dimension of the mask is measured. A target parameter value of the process parameter for achieving a target opening dimension of the concave portion is determined, based on a difference between the actual opening dimension of the mask and the reference opening dimension thereof, the target opening dimension of the concave portion to be formed, and the first and second correlations.

Claims

1. An etching method for subjecting an object to be processed to an etching process, the object including:

a substrate;

a film to be etched that is formed on the substrate; and

a photoresist mask provided with an opening, the photoresist mask being formed on the film;

to form a concave portion in the film;

the etching method comprising the steps of;

determining, in advance, a first correlation between a parameter value of an etching process parameter and an opening dimension of the concave portion, when the etching process is conducted with the use of the mask provided with the opening of a reference opening dimension;

determining, in advance, a second correlation between a variation in opening dimension of the opening the mask and a variation in opening dimension of the concave portion in the film;

measuring an actual opening dimension of the opening in the mask in the object that is to be subjected to the etching process;

determining a target parameter value of the etching process parameter for achieving a target opening dimension of the concave portion, based on a difference between the actual opening dimension of the opening in the mask and the reference opening dimension of the opening in the mask, the target opening dimension of the concave portion to be formed, and the first and second correlations; and

conducting an etching process to the object to be processed, so as to make the etching process parameter correspond to the target etching parameter value, wherein the etching process is conducted by using at least two types of etching gases, and

the etching process parameter is a ratio of flow rates of the etching gases.

2. The etching method according to claim 1,

wherein the film to be etched is a reflection preventing film containing silicon, oxygen, and nitrogen, and

the etching gases are a CF₄ gas and a C₄F₈ gas.

3. A non-transitory computer-readable storage medium storing a control program for performing the etching method according to claim 1 in an etching apparatus.