AVS 49th International Symposium
    Manufacturing Science and Technology Monday Sessions
       Session MS+SE-MoM

Paper MS+SE-MoM5
Measurements of Shallow Trench Isolation by Normal Incidence Optical Critical Dimension Technique

Monday, November 4, 2002, 9:40 am, Room C-109

Session: In-Situ Monitoring and Metrology for Coating Growth and Manufacturing
Presenter: J. Hu, Nanometrics, Inc.
Authors: J. Hu, Nanometrics, Inc.
D. Shivaprasad, Nanometrics, Inc.
F. Yang, Nanometrics, Inc.
R. Korlahalli, Nanometrics, Inc.
Correspondent: Click to Email
Shallow Trench Isolation (STI) has emerged as one of the primary techniques for device isolation in complementary metal-oxide semiconductor (CMOS) technologies. This device isolation technology has become extremely important to satisfy the high density requirements of modern integrated circuits, It is of paramount importance to measure the critical dimensions of the STI structure. Currently used CD-SEMs cannot identify the rounding typically present at the bottom or top of the profile, and it is difficult to differentiate between the top and bottom line-width values. X-SEMs which can give the profile information require the destruction of the wafer. In this paper we present the work done on STI using the Optical Critical Dimension (OCD) technique. This technique measures line or trench profiles using Normal Incidence Polarized Reflectometry with a sensitivity to sub-50nm grating lines. In the OCD technique, a broadband polarized light beam is focused onto the grating surface, and the reflected 0th order is measured as a function of wavelength. The data obtained by measuring the grating structure gives a signature of the profile structure which is analyzed in real time using Rigorous Coupled Wave Analysis (RCWA). Since the data is fitted in real time, there is no requirement for library generation, which makes the analysis simpler and easier to extend to other structures without the need of lengthy re-generation of a new library of profile data. Data from STI wafers before and after ashing (removal of the developed resist) will be presented. Sensitivity to the oxide notching and repeatability data will also be presented.