ISI Product Family

Powerful, Accurate, Cross-Platform Lens Aberration Analysis

Overview

The ISI is an advanced wavefront interferometer providing accurate in-situ measurement of lithography tool lens aberrations. Conforming to standard reticle dimensions and printing on standard wafers, the ISI measures multiple locations in the lens field for fast and flexible full projection lens characterization. ISI presents numerous applications to your lithographic process to improve yield and maximize your lithography tool investment.

ISI comprises an interferometer and a software package for analyzing data received from an overlay tool. The interferometer is used to expose on a standard wafer a pattern in which aberration effects are amplified. One box of the box-in-box target is unaberrated while the other contains aberrated information. The resultant overlay measurements form the basis of the aberration calculation.

InspecStep Interferometer (ISI) ®

For over 7 years ISI has provided industry leading 3^rd party lens aberration analysis. Comprised of a two “reticle” set, the ISI is a cost effective solution for stepper and scanner owners at 365 nm, 248 nm, and 193 nm wavelengths to improve yields and push micro-lithography tools to their optical limits.

High Accuracy InspecStep Interferometer (HA-ISI) ®

Building off of the success of the ISI technology, the HA-ISI significantly improves accuracy for users operating at aggressive technology nodes. Printing aberrated features with smaller dimensions and tighter pitch, the HA-ISI uses a single precisely calibrated “reticle” to approximately double the accuracy of the ISI.

Universal Layout High Accuracy ISI (UL HA-ISI)

The UL HA-ISI extends the high accuracy design with additional functionality and flexibility. Improved coverage of both 25mm and 26mm slit lengths and higher density lens sampling provide a more detailed analysis of the projection lens. The UL HA-ISI also features increased scan direction coverage, to observe immersion fluid flow effects (up to an effective 0.95 numerical aperture) and improved error checking.

Hyper NA ISI™

Not sure how immersion is affecting phase error at the wafer? Hyper NA ISI™ brings accurate in-situ aberration analysis to immersion systems. Measurements can be done “wet” or “dry” up to an effective numerical aperture of 1.37.

	InspecStep Interferometer (ISI)®	High Accuracy InspecStep Interferometer (HA-ISI)®	Universal Layout High Accuracy ISI	Hyper NA ISI™
NA Capability	NAPO max 0.95	NAPO max 0.95	NAPO max 0.95	NAPO max 1.37
Immersion	No	No	No	Yes
Wavelength Capability	Wavelength specific 365 nm, 248 nm, 193 nm	Wavelength specific 248 nm, 193 nm	Wavelength specific 248 nm, 193 nm	193 nm
Zernike	28	37	37	37
Wavefront Repro.	1.40 nm RMS	0.70 nm RMS	0.70 nm RMS	0.70 nm RMS
Single Zernike	0.30 nm RMS	0.12 nm RMS	0.12 nm RMS	0.12 nm RMS
Key Features	Stepper / scanner compatibility ASML / Nikon / Canon cross platform capability	Stepper / scanner compatibility ASML / Nikon / Canon cross platform capability	High density spatial sampling ASML / Nikon / Canon cross platform capability	Up to 1.37 NA immersion capability Compatible with ‘dry’ 193 nm lithography tools ASML / Nikon / Canon cross platform capability
Benefits	Detect aberration changes before yield is impacted Track aberrations and lens degradation over lifetime of litho tool Full field / slit analysis for ACLV analysis and simulation exercises Provides data to match lenses between lithography tool vendors

Features

• Resist based measurements
• Reticle design technology
• No moving or replacement parts
• One instrument can be used w/all OEM’s tools of a given wavelength
• Ability to be used within multi generations of OEM’s lithography tools
• No calibration or maintenance required

Benefits

• Quickly qualify newly installed tools and reduce start-up time
• Resist based measurements require minimal lithography tool downtime
• Combine aberration information with lithographic simulation software to predict printing resolution
• Verify RET masks (OPC, PSM, etc.) will work with a given projection lens
• Tool ranking, tool clustering, and tool matching
• Reduce or eliminate the need for monitor wafers
• Preemptively adjust lens elements before yield is affected
• Verify lens state after major tool changes such as lens adjustments or thermal transients