Alignment strategy for metal layers after W-CMP

Sajan R. Marokkey; Juan Boon Tan; Yan Tse Tak; Alex Tsun-Lung Cheng

doi:10.1117/12.350792

14 June 1999 Alignment strategy for metal layers after W-CMP

Sajan R. Marokkey, Juan Boon Tan, Yan Tse Tak, Alex Tsun-Lung Cheng

Proceedings Volume 3677, Metrology, Inspection, and Process Control for Microlithography XIII; (1999) https://doi.org/10.1117/12.350792
Event: Microlithography '99, 1999, Santa Clara, CA, United States

Abstract

CMP of Tungsten (W) in the wafer process flow pose a major challenge for robust stepper alignment, particularly at tighter design rules for 0.25 micron and beyond. Traditional alignment strategies based on optical diffraction often fail to provide alignment accuracy and consistency, as dictated by the tighter overlay budgets. Intensity based image analysis methods prove to be more successful in the alignment of metal CMP layers. In addition the noise reduction and signal processing capabilities of alignment sensors, the condition of the mark after W-CMP is vital for achieving good alignment. In this paper we report results from various alignment mark designs. The marks are designed to reduce the impact of CMP process variations on stepper alignment. Three types of alignment methods using laser diffraction, bright field imaging and laser interferometry techniques were investigated. The brightfield imaging alignment schemes provide the best results using a narrow trench mark separated by wider islands. Details of stepper alignment signals and overlay measurement results corresponding to some of the relevant mark design sand process variations are included in the paper.

Citation Download Citation

Sajan R. Marokkey, Juan Boon Tan, Yan Tse Tak, and Alex Tsun-Lung Cheng "Alignment strategy for metal layers after W-CMP", Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); https://doi.org/10.1117/12.350792

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available