Characterization in Silicon Processing

Ο

500 1000 1500

Depth (Angstroms)

Figure

1.5

SIMS profiles

of

LRP-grown boron-doped Si epitaxial layer. The

primary beam energy has been varied;

by

extrapolation

of the

profile slopes

to 0

kV, the profile abruptness

is

estimated

to be

<50 Ä/decade. (After Reference 43; reprinted

by

permission

of

J.

E.

Turner, Hewlett-Packard Company.)

voltage

has allowed measurement of

boron

concentration transitions as steep as

50

Â/decade (Figure 1.5).

43

1.4

Selective Growth

Basic Process Considerations

The selective silicon growth process is shown schematically in Figure 1.6. A mask-

ing

material

(typically Si0

2

or

S13N4)

is patterned to expose regions o