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Efficient Calculation of Boron Depletion by a Growing Oxide

IP.com Disclosure Number: IPCOM000061934D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hsieh, CM: AUTHOR [+2]

Abstract

In the new method described, to efficiently calculate the boron depletion of doped silicon which is oxidized, the boundary condition at the interface is calculated. This is in contrast to the more conventional method which uses calculation of the boron diffusion in the oxide.

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Efficient Calculation of Boron Depletion by a Growing Oxide

In the new method described, to efficiently calculate the boron depletion of doped silicon which is oxidized, the boundary condition at the interface is calculated. This is in contrast to the more conventional method which uses calculation of the boron diffusion in the oxide.

When oxide is grown on silicon doped with boron, the boron segregates from the silicon into the oxide and diffuses. Because the diffusion coefficient of the boron in the oxide is substantially smaller than the coefficient in the silicon, the result steep gradient of boron concentration in the oxide. By concentrating calculations on what is occurring in the oxide, the determination of the amount of boron removed from the silicon is difficult.

Because the actual distribution of the boron in the oxide is not of interest for device characteristics, the new method calculates the boron depletion occurring at the boundary interface between the silicon and oxide. The boundary equation used is: FLUXout = {(1/Seg) - 1} (Cb) (V) where, Seg is the segregation ratio between the boron in the silicon to that in the oxide, Cb is the boron concentration in the silicon at THE INTERFACE, AND V is the velocity of the oxide growth.

As the oxide grows the boundary conditions are changed appropriately to correspond to the motion of the interface. The velocity, V, can be calculated from the Grove-Deal relationship or from experimental data. The calculation...