×

Interferometer for in situ measurement of thin film thickness changes

  • US 5,220,405 A
  • Filed: 12/20/1991
  • Issued: 06/15/1993
  • Est. Priority Date: 12/20/1991
  • Status: Expired due to Fees
First Claim
Patent Images

1. An apparatus comprising:

  • first light source means for providing a first light beam of coherent light;

    first beam splitter means for partially transmitting and partially reflecting said first light beam, thereby providing a second light beam and a third light beam, respectively;

    second beam splitter means for partially reflecting and partially transmitting said second light beam, thereby providing a fourth light beam and a fifth light beam, respectively;

    first translating means having a first translating surface which translates a predetermined distance for reflecting said fifth light beam to thereby provide a sixth light beam;

    a substrate having;

    a processing surface, the position of which is to be measured; and

    a back surface, wherein said processing surface reflects said fourth light beam to thereby provide a seventh light beam;

    first measurement means responsive to said sixth and seventh light beams for measuring the phase shift therebetween, wherein the phase shift is a function of the difference in position of the processing surface and the first translating surface and wherein said first measurement means provides a first measurement signal indicative of the relative position of the processing surface;

    third beam splitter means for partially reflecting and partially transmitting said third light beam, thereby providing an eighth light beam and a ninth light beam, respectively;

    second translating means having a second translating surface which translates a predetermined distance for reflecting said ninth light beam to thereby provide a tenth light beam,wherein the back surface reflects said eighth light beam to thereby provide an eleventh light beam;

    second measurement means responsive to said tenth and eleventh light beams for measuring the phase shift therebetween, wherein the phase shift is a function of the difference in position of the back surface and the second translating surface and wherein said second measurement means provides a second measurement signal indicative of the relative position of the back surface; and

    ,comparator means comparing the first and second measurement signals to thereby provide a position output signal.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×