Title :
A two-dimensional low pass filter model for die-level topography variation resulting from chemical mechanical polishing of ILD films
Author :
Tat-Kwan Yu ; Chheda, S. ; Ko, J. ; Roberton, M. ; Dengi, A. ; Travis, E.
Author_Institution :
Motorola Inc., Austin, TX, USA
Abstract :
This paper presents a new two-dimensional (2-D) low pass filter model for the prediction of post-chemical-mechanical polishing (CMP) die level wafer topography variation caused by the interconnect metal density of a circuit layout. It is demonstrated that the local smoothing and planarization effects of an ILD polishing process can be characterized accurately (in the frequency domain) by a polynomial equation with a small number of fitted parameters. In this method, the design specific metal density patterns with millions of shapes are first captured in the frequency domain using a 2-D Fast Fourier Transform (FFT). A fitted low pass filter CMP model is then applied to filter/remove short range pattern variation. (Die level topography variations are not removed by CMP effectively). Finally, the post-CMP smoothed topography in the spatial domain is computed from inverse FFT. Model predictions and experimental data are compared in three examples (a) a test structure, (b) a die with shallow trench isolation (c) cumulative topography of a die after ILD1, 1LD2 and ILD3 polishing.
Keywords :
chemical mechanical polishing; dielectric thin films; fast Fourier transforms; integrated circuit interconnections; low-pass filters; semiconductor process modelling; chemical mechanical polishing; circuit layout; die-level wafer topography; fast Fourier transform; frequency domain; interconnect metal density; interlevel dielectric film; inverse FFT; planarization; polynomial equation; shallow trench isolation; smoothing; two-dimensional low pass filter model; Frequency domain analysis; Integrated circuit interconnections; Low pass filters; Planarization; Polynomials; Predictive models; Semiconductor device modeling; Smoothing methods; Surfaces; Two dimensional displays;
Conference_Titel :
Electron Devices Meeting, 1999. IEDM '99. Technical Digest. International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-5410-9
DOI :
10.1109/IEDM.1999.824296