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Optimized Overlay Measurement Algorithmen (based on existing signal detection software)

IP.com Disclosure Number: IPCOM000017673D
Original Publication Date: 2001-Jul-01
Included in the Prior Art Database: 2003-Jul-23
Document File: 2 page(s) / 19K

Publishing Venue

Siemens

Related People

Sebastian Schmidt: AUTHOR [+3]

Abstract

At the production of memory and logic chips in the field of semi-conductor technology different structured layer must get fine aligned to other below. Currently is one layer in both dimension (X and Y) aligned to the layer below to which it should best fit related to the design manual (Figure 1). An optimized alignment is assuming a measurement of the misregistration in best quality. These measurements are performed at special test structures.

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Bauelemente

Optimized Overlay Measurement Algorithmen (based on existing signaldetection software)

Idee: Sebastian Schmidt, Dresden; Rolf Heine, Berlin; Dietmar Ganz, Dresden

At the production of memory and logic chips in the field of semi-conductor technology differentstructured layer must get fine aligned to other below. Currently is one layer in both dimension (Xand Y) aligned to the layer below to which it should best fit related to the design manual (Figure1). An optimized alignment is assuming a measurement of the misregistration in best quality. Thesemeasurements are performed at special test structures.

The idea for new chip generations is to fit the actual printed layer to one layer in X and another inY direction due to the very tough tolerances. Because both layers use different overlay teststructures which generate different signals it is necessary to use different algorithmen for signaldetection (contrast, slice level, resolution, reference signal) to obtain the best result (Figure 2).

This assures as well a good rework performance as also improved electrical results (yield).

1

1

1

2

2

2

2

1 - reference-layer (etch ) below the actuallayer   for x- and y-direction

2 - actual layer   (resist )

y

y-signal*

Prior art: Control Overlay in x- and y-direction to the same reference in both directions

Figure 1

1

*x-signal = y-signal

x-signal*

x

Measurement of the shift (displacement ) of top layer 2 (resist) to bottom-layer 1 (etch )

Siemens Technik Report

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