Browse Prior Art Database

Improvement of the Process Window at Structuring

IP.com Disclosure Number: IPCOM000018131D
Original Publication Date: 2002-Feb-01
Included in the Prior Art Database: 2003-Jul-23
Document File: 1 page(s) / 144K

Publishing Venue

Siemens

Related People

Thorsten Schedel: AUTHOR [+3]

Abstract

For the evaluation of new technologies huge efforts are necessary to characterize the products behavior in litho and etch. This means that a so called focus exposure matrix (FEM) wafer has to be run. By varying the focus and the exposure dose on the wafer it is possible to measure the process windows for the critical dimension (CD) values and judge the quality of the patterns over the focus range. Currently the process window is mostly limited by semi- or iso- lated structures which can collapse before the meas- ured CD is out of specification. The problem is, that only some well known positions on the wafer can be covered. But there is always the risk that one critical position may be forgotten, because the pattern is not said to be very critical. It is possible, that some resist residues will remain within the pattern area or that pattern lift offs will occur. As a consequence the chip would not work any more. With the help of this method it is possible to avoid yield loss in the early state of the process development. It could also be done on a routine base to make sure that the influ- ences of later process changes do not affect the litho or etch process windows.

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Improvement of the Process Win-dow at Structuring

Industrie

Idee: Thorsten Schedel, Dresden;

Sebastian Schmidt, Dresden;Katrin Palitzsch, Dresden

For the evaluation of new technologies huge effortsare necessary to characterize the products behavior inlitho  and  etch.  This  means  that  a  so called focusexposure  matrix  (FEM)  wafer  has  to  be  run. Byvarying the focus and the exposure dose on the waferit is possible to measure the process windows for thecritical dimension (CD) values and judge the qualityof the patterns over the focus range. Currently theprocess window is mostly limited by semi- or iso-lated structures which can collapse before the meas-ured CD is out of specification. The problem is, thatonly some well known positions on the wafer can becovered. But there is always the risk that one criticalposition may be forgotten, because the pattern is notsaid to be very critical. It is possible, that some resistresidues will remain within the pattern area or thatpattern lift offs will occur. As a consequence the chipwould not work any  more.  With  the  help  of  thismethod it is possible to avoid yield loss in the earlystate of the process development. It could also bedone on a routine base to make sure that the influ-ences of later process changes do not affect the lithoor etch process windows.

Today there is no prior art for an automatic inlinedetection of critical patterns during the process win-dow evaluation.

The inspection for critical patterns is done automati-cally and fast (defect inspection). Everything is donein the production line (without yield loss). A highgrade of automation (defect coordinates can be ac-cessed by SEMs) and normal engineering is possible.The new method has a full wafer / exposure fieldscan.

The influence of other processes, like CMP (Chemi-cal  Mechanical  Plana...