Claims
- 1. A method for determining an endpoint of an etching step performed to etch a recess, which comprises:
providing a wafer having a substrate and a mask formed by a mask layer provided on top of the substrate; performing a wafer alignment step to align the wafer in a vacuum etch chamber; measuring a thickness of the mask layer on top of the substrate to determine a thickness value representing a thickness of the mask layer; performing the step of measuring the thickness of the mask layer while performing the wafer alignment step; forwarding the thickness value to an interferometric endpoint determination system for performing an endpoint algorithm; adding the thickness value to a target depth value of the endpoint algorithm; performing the etching step to etch the recess into the substrate relative to the mask formed by the mask layer; during the etching step, measuring the depth of the recess to obtain a depth value representing the depth of the recess; and stopping the etching step when the depth value reaches a sum of the target depth value and the thickness value.
- 2. The method according to claim 1, which comprises: using a laser measurement system to perform the step of measuring the thickness of the mask layer.
- 3. The method according to claim 2, wherein: the laser measurement system performs ellipsometry.
- 4. The method according to claim 1, which comprises:
performing the step of measuring the thickness of the mask layer by directing a laser beam of a laser measuring system towards a center of the wafer.
- 5. The method according to claim 1, which comprises:
providing a nitride layer as the mask layer.
Priority Claims (1)
Number |
Date |
Country |
Kind |
99119443.2 |
Sep 1999 |
EP |
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of copending International Application No. PCT/EP00/09518, filed Sep. 28, 2000, which designated the United States.
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/EP00/09518 |
Sep 2000 |
US |
Child |
10113344 |
Apr 2002 |
US |