Wafers

 

TRACE METALS

Metal contamination affects IC device operation in various ways. For example, alkali metals such as Na, K, and Li, can cause MOSFET threshold voltage shifts; Al and Zn affect the oxidation rates of silicon; and Fe, Cr, and Cu can cause junction leakage currents and oxide integrity degradation.

At ChemTrace, we utilize vapor phase decomposition (VPD) inductively coupled plasma-mass spectrometry (ICP-MS) to monitor trace metals on wafer surfaces because of its superior method sensitivity and capability to analyze low to high z elements. Standard edge exclusion is 2mm; however, we can provide zero and larger exclusion upon request. Bevel edge and backside contamination capabilities are offered for verifying bevel edge and backside cleaning efficacy in removing novel metallic elements.

Complete repertoire of VPD-related techniques offered:

VPD ICP-MS

Vapor Phase Decomposition Inductively Coupled Plasma – Mass Spectroscopy of total surface, localized radial scan, localized quadrant scan, and bevel edge

• Wafer and film type

  Bare silicon; silicon wafers with films such as silicon nitride, silicon dioxide, CVD oxide, SiOC, SOI, and TEOS oxide

• Target

  Trace metal impurities on and in native oxide or films as indicated above

WSS ICP-MS

Wafer Surface Scan Inductively Coupled Plasma – Mass Spectroscopy

• Wafer and film type

  Any

• Target

  Trace metal impurities on wafer surface

DFS ICP-MS

Direct Film Stripping Inductively Coupled Plasma – Mass Spectroscopy

• Film type

  Metals; high-κ dielectrics; thin films such as Al, Co, Cu, Ge, Mg, Ni, Ti, AlOx, CoOx, HfOx, LaOx, NiOx, TiN,TaOx, TiOx, WSi, ZnOx, ZrOx

• Target

  In-film trace metals impurities (pertains to film quality)

BSE ICP-MS

Bulk Silicon Etch Inductively Coupled Plasma – Mass Spectroscopy

• Wafer and film type

  Silicon substrate, polysilicon, and Epi-Si

• Target

  Trace metal impurities at various depths of silicon substrate, polysilicon film, and Si film

Standard elements offered

11E to include Na, Al, Cr, Fe, Ni, Zn, Ca, K, Cu, Mg, Ti

30E to include Al, As, Sb, Ba, Be, Bi, B, Cd, Ca, Cr, Co, Cu, Ga, Ge, Fe, Pb, Li, Mg, Mn, Mo, Ni, K, Na, Sr, Sn, Ti, V, Zn, Zr, W

40E to include Al, As, Sb, Ba, Be, Bi, B, Cd, Ca, Cs, Cr, Co, Cu, Ga, Ge, Hf, Fe, Pb, Li, Mg, Mn, Mo, Ni, Nb, K, Rb, Sc, Na, Sr, Sn, Ta, Th, Tl, Ti, W, U, V, Y, Zn, Zr

Other elements, including rare earths, are available upon request.

ANIONS AND CATIONS ANALYSIS

Ultrapure water extraction of anions and cations on wafer surface followed by ion chromatography (IC)

Ionics are a leading factor in IC reliability. For example, residual fluoride on Al bond causes bond pad corrosion and staining. Poor rinsing of wafers during SC1, SC2, and dilute HF cleaning processes causes formation of haze on the wafer surface.

• Target

  Residual anions or cations from cleaning chemistries, process gas, process chamber, and cleanroom environment

Standard ionics offered

Anions to include F^-, Cl^-, NO₂^-, Br^-, NO₃^-, SO₄^2-, PO₄^3-

Cations to include Li⁺, Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺

VOLATILE ORGANICS ANALYSIS

Organic outgassing of wafer by automated thermal desorption gas chromatography - mass spectrometry (ATD GC-MS, SEMI MF 1982-1103 for detection of C7-C30 chained volatile organics

• Target

  Speciation and semi-quantitative analysis of volatile organics collected on processed and witness wafers