SYSTEM FOR DIRECTLY MEASURING THE DEPTH OF A HIGH ASPECT RATIO ETCHED FEATURE ON A WAFER

摘要

A system (10) for directly measuring the depth of a high aspect ratio etched feature on a wafer (80) that includes an etched surface (82) and a non-etched surface (84). The system (10) utilizes an infrared reflectometer (12) that in a preferred embodiment includes a swept laser (14), a fiber circulator (16), a photodetector (22) and a combination collimator (18) and an objective lens (20). From the objective lens (20) a focused incident light (23) is produced that is applied to the non-etched surface (84) of the wafer (80). From the wafer (80) is produced a reflected light (25) that is processed through the reflectometer (12) and applied to an ADC (24) where a corresponding digital data signal (29) is produced. The digital data signal (29) is applied to a computer (30) that, in combination with software (32), measures the depth of the etched feature that is then viewed on a display (34).

主权项

1. A system for directly measuring a characteristic of a semiconductor wafer comprising:
a fixture for supporting the semiconductor wafer and for moving the semiconductor wafer in an XY plane; a sensor having an optical axis that is perpendicular to the XY plane in which the fixture moves the semiconductor wafer, the sensor further comprising:
an illumination source that outputs a focused light that is incident upon a non-etched surface of the semiconductor wafer, the focused light including at least one wavelength to which the semiconductor wafer is at least partially transparent; and,a light sensitive spectrometer that receives at least a portion of the focused light that is returned from the semiconductor wafer and which generates an analog spectrum optical frequency signal indicative of the characteristic of the semiconductor wafer at the position at which the focused light is incident upon the semiconductor wafer; and,an analog-to-digital (ADC) converter that receives the analog spectrum optical frequency signal from the light sensitive spectrometer and which outputs a corresponding digital data signal; and,a computer coupled to both the fixture and to the sensor to coordinate their operation and which determines from the digital data signal the characteristic of the semiconductor wafer relative to an etched surface of the wafer that is opposed to the non-etched surface of the wafer.