Novel Noncontact Thickness Metrology for Partially Transparent and Nontransparent Wafers for Backend Semiconductor Manufacturing

Abstract

Single probe infrared low coherence optical interferometry has been proven to be an effective tool for characterization of thin and ultra-thin semiconductor Si and compound materials wafers. Its application was however limited to wafers transparent at probing wavelength, and having relatively smooth surfaces. Purpose of this paper is to present an extension of low coherence interferometry to characterization of non-transparent wafers, and wafers with rough surfaces.

High-speed high-accuracy fiber optic low-coherence interferometry for in situ grinding and etching process monitoring

“…Similar instrument was successfully used in past for metrology of memory [3], and micro-electromechanical devices [4].…”

Fiber optics low-coherence IR interferometry for defense sensors manufacturing

“…Low coherence optical interferometry [1] has been proven to be an effective tool for characterization of thin and ultrathin semiconductor Si wafers, compound materials, MEMs, detector structures, light emitting devices and others [2][3][4][5][6][7][8][9][10][11][12][13][14]. The commonly employed tools for wafer thickness metrology are based on capacitance or air pressure methods.…”

Combined low-coherence interferometry and spectrally resolved reflectometry for nondestructive characterization of small-diameter high-aspect ratio micro-fabricated and micro-machined structures and multilayer membranes

“…In recent three years low coherence fiber optic interferomtery originally developed primarily for biomedical applications [1] became mainstream method for measurement of thickness of wafers for back-end main stream slicon manufacturing [2][3][4]. Low coherence fiber optic interferometer tools allow accurate measurements of thin, and ultrathin wafers mounted on dicing and grinding tapes [2].…”

“…Due to the fact that this method does not require access from both sides of the wafer fiber optic low coherence interferometers became popular tools for monitoring wafer thickness during grinding process in failure analysis laboratories [7]. Recently the same technology found interesting practical applications in compound semiconductor [8], [9], photonics [9], and micro-electromechanical system (MEMS) applications [10], [11], [12], [13].…”