SEMI E45 - Test Method for the Determination of Inorganic Contamination from Minienvironments Using VPD-TXRF, VPD-AAS, or VPD/ICP-MS -
NOTICE: This Standard or Safety Guideline has Inactive Status because the conditions to maintain Current Status have not been met. Inactive Standards or Safety Guidelines are available from SEMI and continue to be valid for use.
This Test Method provides the analytical procedures to determine the level of inorganic contamination from a minienvironment.
This Document relates to inorganic impurities, which includes metallic contaminants, whether they occur as atoms, molecules, or particles. The number of metals to be analyzed is restricted to the four elements sodium (Na), calcium (Ca), iron (Fe), and copper (Cu) in order to rapidly characterize mini-environments from a practicable point of view. While Na, Ca, and Fe represent one ensemble of highly detrimental impurities with respect to contamination from human sources (Na), the environment (Ca), or from equipment and corrosive effects (Fe), Cu is analyzed due to its increasing importance in semiconductor manufacturing. Additionally, they are easily analyzed with sufficiently low detection limits. It is up to the user of this test method to quantify additional elements. A list of suggested polished wafer surface metal contamination inappropriate to circuits and devices is shown in Table 1 (based on SEMI M1). The inorganic contamination on silicon wafer surfaces is collected by VPD.
To quantify Ca and Fe, VPD/TXRF is used due to its sufficiently low detection limits. Na and Cu are quantified by VPD/GFAAS or VPD/ICP-MS. All analytical methods are widely used for the characterization of surface cleanliness.
This measurement technique can also be used to check the influence of certain process steps on minienvironments.
Referenced SEMI Standards (purchase separately)
SEMI C28 — Specifications for Hydrofluoric Acid
SEMI C35 — Specifications and Guide for Nitric Acid
SEMI E19 — Specification for Standard Mechanical Interface (SMIF)
SEMI M1 — Specification for Polished Monocrystalline Silicon Wafers
SEMI E45-1101 (Reapproved 0307)
SEMI E45-1101 (technical revision)
SEMI E45-0301 (technical revision)
SEMI E45-1000 (technical revision)
SEMI E45-95 (first published)
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