Etching method and etching apparatus

• US 20070284335A1
• Filed: 03/29/2007
• Published: 12/13/2007
• Est. Priority Date: 03/30/2006
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Tsujimoto, Hiroshi
• Granted Patent: US 8,070,972 B2
• Time in Patent Office: Days
• 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 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;

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

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

determining a target parameter value of the process parameter for achieving a target opening dimension of the concave portion, based on a difference between the actual opening dimension of the mask and the reference opening dimension of 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 process parameter correspond to the target parameter value.

2. The etching method according to claim 1,

wherein the etching process is conducted by using at least two types of etching gases, and

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

3. The etching method according to claim 2, 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.

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

4. An etching apparatus 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 apparatus comprising;

(i) a storage section that stores;

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; and

a second correlation between a variation in opening dimension of the mask and a variation in opening dimension of the concave portion;

(ii) means for determining a target parameter value of the process parameter for achieving a target opening dimension of the concave portion, based on;

a difference between an actual opening dimension of the mask measured in the object that is to be subjected to the etching process, and the reference opening dimension of the mask;

the target opening dimension of the concave portion to be formed; and

the first and second correlations stored in the storage section; and

(iii) means for conducting an etching process to the object to be processed, so as to make the process parameter correspond to the target parameter value.

5. The etching apparatus according to claim 4,

wherein the means for conducting an etching process conducts an etching process by using at least two types of etching gases, and

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

6. The etching apparatus according to claim 5,

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.