APPARATUS WITH ENHANCED RESOLUTION FOR MEASURING STRUCTURES ON A SUBSTRATE FOR SEMICONDUCTOR MANUFACTURE AND USE OF APERTURES IN A MEASURING APPARATUS

• US 20080278790A1
• Filed: 05/01/2008
• Published: 11/13/2008
• Est. Priority Date: 05/07/2007
• Status: Active Grant

• Current Assignee: Vistec Semiconductor Systems GmbH (Dr. Johannes Heidenhain GmbH)
• Original Assignee: Vistec Semiconductor Systems GmbH (Dr. Johannes Heidenhain GmbH)
• Inventors: Boesser, Hans-Artur, Steinberg, Walter
• Granted Patent: US 7,982,950 B2
• Time in Patent Office: Days
• US Class Current: 359/227
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams

Abstract

A measuring system is disclosed with enhanced resolution for periodic structures on a substrate for semiconductor manufacture. Aperture structures of varying geometries are provided in the illumination beam path. The aperture structures differ regarding the transmission characteristics of light, and which adjust the intensity distribution of the diffraction orders in the imaging pupil of the optical system.

Claims

1. A measuring system with enhanced resolution for periodic structures on a substrate for semiconductor manufacture, comprising a condenser with an entrance pupil, wherein the condenser can be configured as a measuring objective and aperture structures provided in an illumination beam path, for changing the distribution of the intensities of the orders of diffraction in an imaging beam path.

2. The measuring system according to claim 1, wherein the aperture structures are adjustable and/or pivotable, to enable evaluation of a measurement with different apertures.

3. The measuring system according to claim 1, wherein the aperture structures are annular, wherein a circular inner area is opaque and an annular outer area is transparent.

4. The measuring system according to claim 3, wherein the circular inner area shows a transmission which declines toward the center in accordance with a function and wherein the annular outer area is transparent.

5. The measuring system according to claim 4, wherein the transmission declines toward the center of the circular inner area in accordance with a cosine function.

6. The measuring system according to claim 3, wherein the diameter of the circular inner area and the width of the annular outer area are variable.

7. The measuring system according to claim 3, wherein the annular aperture structure is formed as an LCD, with which the diameter of the circular inner area and the width of the annular outer area, as well as the transmission of the inner area can be adjusted, in order to compensate the ratio of diffracted light to undiffracted light on the structures to be measured using the adjustable aperture structures.

8. The measuring system according to claim 1, wherein a coherent illumination is provided for illuminating the structures.

9. Use of an aperture structure in a measuring system for periodic structures on a substrate for semiconductor manufacture, comprising a condenser with an entrance pupil, and an aperture structure is provided in the entrance pupil of the condenser.

10. The use according to claim 9, wherein the aperture structures are adjustable and/or pivotable, to enable evaluation of a measurement to be carried out with different apertures.

11. The use according to claim 9, wherein the aperture structures are annular and a circular inner area is opaque and an annular outer area is transparent.

12. The use according to claim 11, wherein the transmission of the circular inner area declines toward the center in accordance with a function, and in that the annular outer area is transparent.

13. The use according to claim 12, wherein the transmission declines toward the center of the circular inner area in accordance with a cosine function.

14. The use according to claim 12, wherein the diameter of the circular inner area and the width of the annular outer area are variable.

15. The use according to claim 11, wherein the annular aperture structure is formed as an LCD, with which the diameter of the circular inner area and the width of the annular outer area, as well as the transmission of the inner area can be adjusted.