Bow and warp of semiconductor wafers and substrates
Encyclopedia
Bow and warp of semiconductor wafers and substrates are measures of the flatness of wafers
.
from the median surface to the reference plane. Where the reference plane is defined by three corners of equilateral triangle. This definition is based on now obsolete ASTM
F534.
Warp is the difference between the maximum and the minimum distances of the median surface of a free, un-clamped wafer from the reference plane defined above. This definition follows ASTM F657 , and ASTM F1390.
wafer thickness gauges such as ADE 9500 , and later adopted by optical gauges .
Even though these standards are currently obsolete
. They were withdrawn without replacement and but are still widely used for characterization of semiconductor wafers, metal and glass substrates
for MEMS
devices, solar cell
s, and many other applications.
Wafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
.
Definitions
Bow is the deviation of the center point of the median surface of a free, un-clamped waferWafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
from the median surface to the reference plane. Where the reference plane is defined by three corners of equilateral triangle. This definition is based on now obsolete ASTM
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
F534.
Warp is the difference between the maximum and the minimum distances of the median surface of a free, un-clamped wafer from the reference plane defined above. This definition follows ASTM F657 , and ASTM F1390.
Modifications
The above definitions were developed for capacitanceCapacitance
In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
wafer thickness gauges such as ADE 9500 , and later adopted by optical gauges .
Even though these standards are currently obsolete
Obsolescence
Obsolescence is the state of being which occurs when an object, service or practice is no longer wanted even though it may still be in good working order. Obsolescence frequently occurs because a replacement has become available that is superior in one or more aspects. Obsolete refers to something...
. They were withdrawn without replacement and but are still widely used for characterization of semiconductor wafers, metal and glass substrates
Substrate (semiconductor)
Substrate is a solid substance onto which a layer of another substance is applied, and to which that second substance adheres. In solid-state electronics, this term refers to a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide , an alloy...
for MEMS
Microelectromechanical systems
Microelectromechanical systems is the technology of very small mechanical devices driven by electricity; it merges at the nano-scale into nanoelectromechanical systems and nanotechnology...
devices, solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
s, and many other applications.