Method of estimating lifetime of floating SOI-MOSFET

• US 6,173,235 B1
• Filed: 09/06/1996
• Issued: 01/09/2001
• Est. Priority Date: 04/11/1996
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Maeda, Shigenobu
• Primary Examiner(s): Stamber, Eric W.
• Application Number:
  US08/709,079
• Time in Patent Office: 1,586 Days
• Field of Search: 364/480, 364/481, 364/551.01, 364/552, 364/578, 324/537, 324/765, 324/766, 324/769, 324/770, 257/66, 257/69, 257/213, 257/236, 257/288, 257/314, 257/315, 437/8, 437/913, 437/923, 702/57, 702/58, 702/64, 702/81, 702/182, 702/183, 702/117, 438/4, 438/14, 438/15, 438/16, 438/17, 438/18, 438/197
• US Class Current: 702/58
• CPC Class Codes: G01R 31/2621 for testing field effect transistors, i.e. FET's
• CPC Class Codes: G01R 31/2642 Testing semiconductor operation lifetime or reliability, e.g. by accelerated life tests

Abstract

In a method of estimating the lifetime of a floating SOI-MOSFET, constants A and B, stress condition dependency Id_t(S) of a drain current and stress condition dependency Isub(S) of a substrate current in a body-fixed SOI-MOSFET, and stress condition dependency Id^f(S) of a drain current in the floating SOI-MOSFET are obtained from experiment to estimate lifetime υ_f(S) from the following equation: $\begin{array}{cc}{\tau }^f\left(S\right)=A·W^f\frac{1}{{\mathrm{Id}}^f\left(S\right)}{\left(\frac{\mathrm{Isub}\left(S\right)}{{\mathrm{Id}}^{t}\left(S\right)}\right)}^{-B}& \left(5\right)\end{array}$

where W^f represents a known channel width of the floating SOI-MOSFET.

Claims

1. A method of estimating a lifetime of a floating SOI-MOSFET, comprising the steps of:

measuring a drain current Id^f in said floating SOI-MOSFET;

measuring a drain current Id^t and a substrate current Isub in a body-fixed SOI-MOSFET;

estimating a hole current Ih^f of said floating SOI-MOSFET under a hot carrier stress condition based on an approximation equation;

Ih^f≈

(Id^f/Id^t)Isub; and

estimating a lifetime of said floating SOI-MOSFET by using said estimated hole current Ih^f.

2. A method of estimating a hole current Ih^f of a floating SOI-MOSFET, comprising the steps of:

measuring a drain current Id^f in said floating SOI-MOSFET;

measuring a drain current Id^t and a substrate current Isub in a body-fixed SOI-MOSFET; and

estimating a hole current Ih^f of said floating SOI-MOSFET under a hot carrier stress condition based on an approximation equation;

Ih^f≈

(Id^f/Id^t)Isub.