Browse Prior Art Database

ORGANIC SUBLAYER FOR ENDPOINT DETECTION

IP.com Disclosure Number: IPCOM000006057D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2001-Nov-29
Document File: 3 page(s) / 206K

Publishing Venue

Motorola

Related People

John Helbert: AUTHOR [+4]

Abstract

Etchback planarization is an integral part of many wafer processing operations. It is widely used in multilevel metallizations and trench isolations. The typical process utilizes a 1:l plasma etchback chemistry for the organic overcoat, e.g. photoresist, to the oxide dielectric. Stopping the etch prior to exposing the underlying structures is not an easily controllable task. By adding a optically different organic between the oxide and the organic overcoat, a laser reflectometer endpoint signal can be obtained. The application of this technique is described in the following.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 3

0 M

MOTOROLA INC. Technical Developments Volume 12 April 1991

ORGANIC SUBLAYER FOR ENDPOINT DETECTION

by John Helbert, Jeffrey Pearse, Clarence Tracy and John Vogel

  Etchback planarization is an integral part of many wafer processing operations. It is widely used in multilevel metallizations and trench isolations. The typical process utilizes a 1:l plasma etchback chemistry for the organic overcoat, e.g. photoresist, to the oxide dielectric. Stopping the etch prior to exposing the underlying structures is not an easily controllable task. By adding a optically different organic between the oxide and the organic overcoat, a laser reflectometer endpoint signal can be obtained. The application of this technique is described in the following.

  The wafer processing sequence is shown in figures 1 through 3. The difference in this current invention occurs with the application of a thin (c2000.&) organic spin on coating. This sublayer is compatible with the overcoat organic processing and differs primarily only in its optical absorbance or reflectance properties.

  Wafer processing continues with loading into a reactive ion or plasma etcher, where a laser is aimed at the wafer surface to provide an amplitude modulated reflectance signal ',2. During the etch, the process is controlled to near 1 to 1 etch rates of the organic and oxide, so as to provide a planar surface upon completion. A reflectometer trace of a wafer prepared without the sublayer is shown in figure 4. Note there

is no change in amplitude nor period as the etch progresses through the organic into the oxide. Figure 5 shows the amplitude change obtained by the use of a dyed organic sublayer. Here the signal increases as the dyed layer is removed, exposing the oxide. An antireflective coating, ARC, wi...