Method for monitoring ion implant doses
AssigneeTECH Semiconductor Singapore Pte Ltd
InventorsSiew Fong Wee, Luey Chwan Liong
Life of this patent
Estimating the term…
Abstract
Both the sensitivity and the reproducibility of processes for measuring low density ion implant doses near a semiconductor surface have been improved by first forming a thermal oxide layer on the surface and then adjusting the implant profile so that it peaks at the semiconductor-oxide interface. Additionally, variations in the initial wafer surface condition have been minimized by controlling the charging dose and sequence prior to performing the measurements.
Claims38
A method to improve reproducibility of surface photovoltage measurements of a semiconductor, comprising
- forming a dielectric layer on said semiconductor surface, thereby creating a dielectric-semiconductor interface;
- implanting ions, having an energy range, such that said implanted ions have their maximum concentration level at said dielectric-semiconductor interface;
- and
- then performing said surface photovoltage measurements.
A method to improve reproducibility of surface photovoltage measurements of a semiconductor, comprising
- implanting ions, having a narrow energy range, into said semiconductor;
- then forming a dielectric layer on said semiconductor surface, thereby creating a dielectric-semiconductor interface, said dielectric layer having a thickness selected so that said implanted ions have their maximum concentration level at said dielectric-semiconductor interface;
- and
- then performing said surface photovoltage measurements.
A method to bias a semiconductor surface prior to performing surface photo-voltage measurements, comprising
- determining an amount of charge that is needed to bias said semiconductor surface into full depletion;
- and
- then injecting into the semiconductor a succession of at least two light pulses whose total photon energy is sufficient to create said amount of charge in the semiconductor.
A method for measuring an implanted ion dose in a semiconductor having a surface, comprising
- forming a dielectric layer on said semiconductor surface, thereby creating a dielectric-semiconductor interface;
- implanting ions, having an energy range, into said semiconductor such that said implanted ions have their maximum concentration level at said dielectric-semiconductor interface;
- determining an amount of charge that is needed to bias said semiconductor surface into full depletion;
- then injecting into the semiconductor a succession of at least two light pulses whose total photon energy is sufficient to create said amount of charge, thereby biasing said surface;
- applying a light pulse of known energy content to said surface and then measuring a resulting photovoltage using a non-contacting electrode;
- and
- from said measured photovoltage computing said implanted ion dose.
A method for measuring an implanted ion dose in a semiconductor having a surface, comprising
- implanting ions, having a narrow energy range, into said semiconductor;
- then forming a dielectric layer on said semiconductor surface, thereby creating a dielectric-semiconductor interface, said dielectric layer having a thickness selected so that said implanted ions have their maximum concentration level at said dielectric-semiconductor interface;
- determining an amount of charge that is needed to bias said semiconductor surface into full depletion;
- then injecting into the semiconductor a succession of at least two light pulses whose total photon energy is sufficient to create said amount of charge, thereby biasing said surface;
- applying a light pulse of known energy content to said surface and then measuring a resulting photovoltage using a non-contacting electrode;
- and
- from said measured photovoltage computing said implanted ion dose.
Dependencies are inferred from the claim text.