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Deep Via Inspection Method by Absorbed Electron Image

IP.com Disclosure Number: IPCOM000117549D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 83K

Publishing Venue

IBM

Related People

Nishikawa, A: AUTHOR [+2]

Abstract

Disclosed is a method to inspect the deep and narrow hole made by absorbed electron. When the shapes are very small size (0.1um - 100um), Secondary Electron Microscope (SEM) by Secondary Electron Image (SEI) are often used. But, the bottom of the deep and narrow hole by SEM cannot be observed.

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Deep Via Inspection Method by Absorbed Electron Image

      Disclosed is a method to inspect the deep and narrow hole made
by absorbed electron.  When the shapes are very small size (0.1um -
100um), Secondary Electron Microscope (SEM) by Secondary Electron
Image (SEI) are often used.  But, the bottom of the deep and narrow
hole by SEM cannot be observed.

      Figs. 1a,b,c show the basic theory.  a) is the case of the
shallow wide hole.  b), c) are observations of the deep narrow hole.
Primary electron (1) is emitted toward the bottom of the hole.
Secondary electron (2) can't escape from deep narrow hole (5) and the
detector (3) can't detect it, because secondary electron (2) has only
weak energy.  Absorbed electron (6) is well detected as absorbed
current.

      Fig. 2 shows the condition of primary electron (1).  In case of
accelerated voltage of primary electron, (1) is very low (under few
keV), the current (7) by absorbed electron has the information of
surface of  sample.  S/N ratio of the image depends on primary beam
current.

      Fig. 3 shows basic usage.  There are two types of contact hole
(deep narrow hole (5)).  One (type A) connects with diffusion layer
(8), the other (type B) connects with the gate electrode (polr-Si) of
MOS FET (10).  Ia (absorbed current of type A (9)) is larger than Ib
(absorbed current of type B (12)).  Consequently, a brighter image of
type A than type B can be observed.

      Fig. 4 shows the applicat...