W4NXE4C-LD00 View Datasheet(PDF) - Cree, Inc

Part Name

Description

Manufacturer

W4NXE4C-LD00

Silicon Carbide Substrates

Cree, Inc 

Standard Specifications

Effective December 1998 • Revised March 2003 • Page 11

STANDARD SPECIFICATIONS FOR POLISHED SILICON CARBIDE

SUBSTRATES - Surface Finish

Definition of Terminology and Methods

(Area) Contamination

Any foreign matter on the surface in localized areas

which is revealed under high intensity (or diffuse)

illumination as discolored, mottled, or cloudy appear-

ance resulting from smudges, stains or water spots.

Cracks

A fracture or cleavage of the wafer that extends from

the frontside surface of the wafer to the back-side

surface of the wafer. Cracks must exceed 0.010” in

length under high intensity illumination in order to

discriminate fracture lines from allowable crystalline

striations. Fracture lines typically exhibit sharp, thin

lines of propagation, which discriminate them from

material striations.

Edge Chips

Any edge anomalies (including wafer saw exit marks)

in excess of 1.5 mm in either radial depth or width. As

viewed under diffuse illumination, edge chips are

determined as unintentionally missing material from

the edge of the wafer.

Edge Exclusion

The outer 2 mm annulus of the wafer is designated as

wafer handling area and is excluded from surface finish

criteria (such as scratches, pits, haze, contamination,

craters, dimples, grooves, mounds, orange peel and saw

marks).

Hex Plate

Hexagonal shaped platelets on the surface of the wafer

which appear silver in color to the unaided eye, under

diffuse illumination.

Masking Defects (also referred to as “Mound”)

A distinct raised area above the wafer frontside surface

as viewed with diffuse illumination.

Orange peel

Visually detectable surface roughening when viewed

under diffuse illumination.

Pits

Individual distinguishable surface anomalies, which

appears as a depression in the wafer surface with a

length-to-width ratio less than 5 to 1, and visible under

high intensity illumination.

Foreign Polytypes (also referred to as “Inclusions” or

“Crystallites”)

Regions of the wafer crystallography which are poly-

crystalline or of a different polytype material than the

remainder of the wafer, such as 4H mixed in with a 6H

type wafer. Poly regions frequently exhibit color

changes or distinct boundary lines, and are judged in

terms of area percent under diffuse illumination.

Scratches

A scratch is defined as a singular cut or groove into the

frontside wafer surface with a length-to-width ratio of

greater than 5 to 1, and visible under hight intensity

illumination.

Striations

Striations in silicon carbide are defined as linear

crystallographic defects extending down from the

surface of the wafer which may or may not pass

through the entire thickness of the wafer, and generally

follow crystallographic planes over its length.

Total Usable Area

A cumulative subtraction of all noted defect areas from

the frontside wafer quality area within the edge exclu-

sion zone. The remaining percent value indicates the

proportion of the frontside surface to be free of all

noted defects (does not include 2mm edge exclusion).

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