PROCESSING TERMINATION DETECTION METHOD AND APPARATUS

• US 20080078948A1
• Filed: 09/24/2007
• Published: 04/03/2008
• Est. Priority Date: 10/03/2006
• Status: Abandoned Application

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: SAITO, Susumu
• Application Number:
  US11/859,971
• Publication Number:
  US 20080078948A1
• Time in Patent Office: Days
• US Class Current: 250/492.2
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32

Abstract

A processing termination detection method capable of accurately performing changeover of etch rates when a residual film thickness of a to-be-processed layer decreases to a predetermined value. A substrate processing apparatus starts first etching to form a through-hole in a single crystal silicon layer of a wafer. A processing termination detection apparatus irradiates laser light comprised of red to near-infrared light onto the wafer and performs a frequency analysis of reflected light received from the wafer. When the intensity, represented in a result of the frequency analysis, in a frequency band corresponding to residual layer interference light has exceeded a threshold value, second etching is started to remove a through hole formation portion of the single crystal silicon layer to cause a silicon oxide layer to be exposed.

Claims

1. A processing termination detection method for use in forming a process hole in a to-be-processed layer of a substrate comprised of at least an underlayer, the to-be-processed layer, and a mask layer, which are formed in layers in this order, comprising:

an irradiation step of irradiating light of long wavelength onto the substrate;

a light reception step of receiving reflected light from surfaces of at least the to-be-processed layer, the underlayer, and the mask layer of the substrate;

a frequency analysis step of performing a frequency analysis of a waveform of received reflected light;

an intensity determination step of determining whether an intensity at a predetermined frequency represented in a result of the frequency analysis exceeds a predetermined threshold value; and

a processing rate changeover step of changing a processing rate of the to-be-processed layer when it is determined that the intensity at the predetermined frequency exceeds the predetermined threshold value.

2. The processing termination detection method according to claim 1, including:

a differentiation step of taking a second-order derivative of the waveform of the received reflected light after the processing rate is changed;

a derivative value determination step of determining whether a variation in a value of the second-order derivative falls within a predetermined range; and

a processing termination step of stopping processing on the to-be-processed layer when it is determined that the variation in the value of the second-order derivative falls within the predetermined range.

3. The processing termination detection method according to claim 1, including:

a difference step of taking a second-order difference of the waveform of the received reflected light after the processing rate is changed;

a difference value determination step of determining whether a variation in a value of the second-order difference falls within a predetermined range; and

a processing termination step of stopping processing on the to-be-processed layer when it is determined that the variation in the value of the second-order difference falls within the predetermined range.

4. The processing termination detection method according to claim 1, wherein the underlayer is a silicon oxide layer, the to-be-processed layer is a single crystal silicon layer, and the process hole is a through-hole.

5. The processing termination detection method according to claim 4, wherein the light of long wavelength irradiated onto the substrate is comprised of red to near-infrared light.

6. The processing termination detection method according to claim 5, wherein the light of long wavelength has a wavelength thereof falling within a range from 650 nm to 1000 nm.

7. A processing termination detection apparatus for detecting a processing termination point in formation of a process hole in a to-be-processed layer of a substrate comprised of at least an underlayer, the to-be-processed layer, and a mask layer, which are formed in layers in this order, comprising:

an irradiation section adapted to irradiate light of long wavelength onto the substrate;

a light receiving section adapted to receive reflected light from surfaces of at least the to-be-processed layer, the underlayer, and the mask layer of the substrate;

a frequency analyzer adapted to perform a frequency analysis of a waveform of the received reflected light;

an intensity determination section adapted to determine whether an intensity at a predetermined frequency represented in a result of the frequency analysis exceeds a predetermined threshold value; and

a processing rate changeover section adapted to change a processing rate of the to-be-processed layer when it is determined that the intensity at the predetermined frequency exceeds the predetermined threshold value.

8. The processing termination detection apparatus according to claim 7, including:

a differentiator adapted to take a second-order derivative of the waveform of the received reflected light after the processing rate is changed;

a derivative value determination section adapted to determine whether a variation in a value of the second-order derivative falls within a predetermined range; and

a processing termination section adapted to stop processing on the to-be-processed layer when it is determined that the variation in the value of the second-order derivative falls within the predetermined range.

9. The processing termination detection apparatus according to claim 7, including:

a difference determinator adapted to take a second-order difference of the waveform of the received reflected light after the processing rate is changed;

a difference value determination section adapted to determine whether a variation in a value of the second-order difference falls within a predetermined range; and

a processing termination section adapted to stop processing on the to-be-processed layer when it is determined that the variation in the value of the second-order difference falls within the predetermined range.