Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2007-12-18
2007-12-18
Benson, Walter (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S639000
Reexamination Certificate
active
10559921
ABSTRACT:
The present invention relates to measurement of conductivity. A microwave oscillated by an oscillator using a Gunn diode is applied through an isolator, a circulator, and a horn antenna to a silicon wafer. The isolator is used for reducing the standing wave influencing the operation of the instrument. The reflected wave is received by the same horn antenna, detected by a detector connected to the circulator, and outpufted in the form of a voltage. The detector produces an output voltage proportional to the square of the amplitude of an electric field. Since the amplitude of the reflected wave from a silicon wafer is proportional to the absolute value of the reflectance, the output voltage is also proportional to the square of the absolute value of the reflectance. The reflectance is in a certain relationship with the conductivity, the conductivity of the silicon wafer can be determined.
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“Contactless measurement of electrical conductivity of semiconductor wafers using the reflection of millimeter waves”, Ju et al., Journal of Applied Physics Letters, vol. 81n19, 2002, pp. 3585-3587.
Benson Walter
Hayes & Soloway P.C.
Tohoku Techno Arch Co., Ltd.
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