Sunrise Optical LLC
4851 NW 103rd Avenue
Sunrise FL 33351
Tel: 1 215 740 4831
Fax: 1 954 748 2302
Below we summarised definitions of few most important terms used when
discussing specifications of our technologies:
Bow of a semiconductor wafer is the deviation of the center point of the
median surface of a free, unclamped wafer from a median-surface reference
plane established by three points equally spaced on a circle with diameter a
specified amount less than the nominal diameter of the wafer [ASTM
F1241]. In SOOLC tools we replace “a median plane” by “the front plane”
of the wafer.
Warp of a free, unclamped semiconductor wafer is the difference between
the maximum and minimum distances of the median surface from a reference
plane [ASTM F1241]. In SOOLC tools we replace “a median plane” by
“the front plane” of the wafer.
Waviness is the more widely spaced component of surface texture.
Waviness may be caused by such factors as machine or work piece
deflections, vibration, and chatter. Roughness may be considered as
superimposed on a wavy surface. [ASTM F1241]
Flatness is the deviation of the front surface, expressed in total indicator
reading (see TIR defined below) relative to a specified reference plane when
the back surface of the wafer is ideally flat, as when pulled down by a
vacuum onto an ideally clean, flat chuck. [SEMI M1-94 and ASTM F1241]
. Also see global flatness and site flatness. For the in a ceramic package
flatness is the allowable deviation of a surface from a defined reference
plane. The tolerance zone is defined by two parallel planes within which the
surface must lie. [SEMI G61-94].
TIR (total indicator reading)
TIR of a semiconductor wafer, is the span of readings, from minimum to
maximum, for any dimension measured. [SEMI G39-89]
TTV (total thickness variation)
TTV of a semiconductor wafer, is the difference between the maximum and
minimum values of the thickness of the wafer. [ASTM F1241]
Please note that ASTM F1241-95(2000) Standard Terminology of Silicon
Technology was withdrawn in 2003.