Surface Defects

chip – region where material has been removed from the surface or edge of the wafer. The size of a chip is defined by its maximum radial depth and peripheral chord length as measured on an orthographic shadow projection of the specimen outline. Also known as clamshell, conchoidal fracture, edge chip, flake, nick, peripheral chip, peripheral indent, and surface chip.  

contamination – a broad category of foreign matter visible to the unaided eye on the wafer surface. In most cases, it is removable by gas blow off, detergent wash, or chemical action. See also particulate contamination, stain.

crack – cleavage that extends to the surface of a wafer and which may or may not pass through the entire thickness of the wafer. Also known as fissure; see also fracture.
 
cratering – a surface texture of irregular closed ridges with smooth central regions.

crow's-foot – intersecting cracks in a pattern resembling a “crow`s foot” (Y) on <111> surfaces and a cross (+) on <100> surfaces.

dimple – a smooth surface depression, larger than 3 mm in diameter, on a wafer surface.

fracture – a crack with single or multiple lines radiating from a point.

groove – a shallow scratch with rounded edges, usually the remnant of a scratch not completely removed during polishing.

haze – a cloudy or hazy appearance attributable to light scattering by concentrations of microscopic surface irregularities such as pits, mounds, small ridges or scratches, particles, etc.
    
imbedded abrasive grains – abrasive particles mechanically forced into the surface of the silicon wafer. This type of contamination may occur during slicing, lapping, or polishing.
   
indent – an edge defect that extends from the front surface to the back surface of the silicon wafer.
   
light point defects (LPD) - individual fine points of reflected light seen when the wafer is illuminated by a narrow-beam light source held perpendicular to the wafer surface.
    
mound – irregularly shaped projection with one or more facets. Mounds can be extensions of the bulk material or various forms of contamination, or both. A high density of mounds can also appear as haze.
   
orange peel – a large-featured, roughened surface, similar to the skin of an orange, visible to the unaided eye under fluorescent light but not usually under narrow-beam illumination.
  
particulate contamination – a form of contamination comprising particles, such as dust, lint, or other material resting on the surface of the wafer and standing out from the surface. May usually be blown off the surface with clean, dry nitrogen.
 
pit – a depression in the surface where the sloped sides of the depression meet the wafer surface in a distinguishable manner (in contrast to the rounded sides of a dimple).
 
saw blade defect – a roughened area visible after polishing with a pattern characteristic of the saw blade travel. It may be descernible before chemical polishing. Also known as saw mark.
  
scratch – a shallow groove or cut below the established plane of the surface, with a length-to-width ratio greater than 5:1. A macroscratch is =0.12µm in depth and is visible to the unaided eye under both incandescent (narrow-beam) and fluorescent illumination. A microscratch is <0.12µm in depth and is not visible to the unaided eye under flourescent illumination.
    
spike – a tall, thin dendrite or crystalline filament which often occurs at the center of a recess in the surface of an epitaxial layer.
   
stain – a form of contamination such as a streak, smudge, or spot which contains foreign chemical compounds such as organics or salts.

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