Evaluation of Si wafer surface condition using 65-degree incident ATR PRO650G

Measuring/analyzing the semiconductor surface of an Si substrate or the like is mandatory for knowing the condition or the contamination condition of thermally oxidized film that functions as insulating film. For the surface analysis, such measures as XPS (X-ray photoelectron spectroscopy, ESCA) and SIMS (secondary ion mass spectrometry) are popularly employed, and such measures give elemental information on the sample surfaces.

On the other hand, infrared spectroscopy (IR) easily obtains information on the molecular bonding condition, which cannot be analyzed by XPS or SIMS in a nondestructive manner. For the surface analysis in IR, the ATR method is popularly employed. For the 45-degree incident ATR, which is used in general, measurement of samples of Si wafers or the like with a high refractive index was difficult, since it does not satisfy the total reflection conditions required for ATR measurement. With the single reflection 65-degree incident ATR we developed recently, Ge with a high refractive index (n = 4.0) is used for the prism, and the incident angle of light to the sample is set at 65 degrees, thereby obtaining information on the topmost surface and measuring samples with a high refractive index, such as Si (refractive index=approx. 3.4) and rubber containing carbon whose refractive index is 2.8 or higher.