公开(公告)号：JPH04340404A

公开(公告)日：1992-11-26

申请号：JP26866491

申请日：1991-09-20

Applicant: IBM

Inventor： TONII FUREDERITSUKU HAINTSU ,  GEIRII SUTEYUWAATO SERUUIN ,  JIYOSHII SHINGU ,  JIYON ANSONII SUPINATSUTEI JIY

IPC: B44C1/22 ,  C23F4/00 ,  G01B11/06 ,  H01L21/66

Abstract: PURPOSE: To monitor the deposition, reaction, modification and removing processes of a material on the spot with high accuracy by irradiating a portion of the surface of the material with a laser beam of predetermined frequency and observing the reflected beam at a specified frequency. CONSTITUTION: A pulse of frequency ω from a laser 12 is polarized through a polarizer 14 and passed through a filter 15 passing only the component of frequency ω and removing other components, especially second harmonic 2ω. A laser beam is reflected on a mirror 17 toward a desired portion of a sample 19 from which a coherent beam of frequency 2ω is generated and directed toward is mirror 21 together with the beam of frequency ω. The mirror 21 transmits the majority of wave of frequency ω and reflects the harmonic 2ω. A polarization beam splitter 24 divides the reflected wave into two through a polarization division and the divided waves are delivered on two detection channels. Outputs from photodetectors 27, 31 are then measured for each channel by means of high rate gate integrators 32, 33. A comparison circuit 34 subtracts the electric outputs of respective channels from each other to produce a difference signal which is used for monitoring the physical processing of the tample 19.