Use of diffracted light from latent images to improve lithography control

Journal Article · · Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States)

DOI:https://doi.org/10.1116/1.586198· OSTI ID:5038903

Hickman, K C; Gaspar, S M; Bishop, K P; Naqvi, S S.H.; McNeil, J R ^[1]; Tipton, G D; Stallard, B R; Draper, B L ^[2]

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1. Univ. of New Mexico, Albuquerque, NM (United States)
2. Sandia National Lab., Albuquerque, NM (United States)

As the microelectronics industry strives to achieve smaller device design geometries, control of linewidth, or critical dimension (CD), becomes increasingly important. Currently, CD uniformity is controlled by exposing large numbers of samples for a fixed exposure time which is determined in advance by calibration techniques. This type of control does not accommodate variations in optical properties of the wafers that may occur during manufacturing. In this work, a relationship is demonstrated between the intensity of light diffracted from a latent image consisting of a periodic pattern in the undeveloped photoresist and the amount of energy absorbed by the resist material (the exposure dose). This relationship is used to simulate exposure control of photoresist on surfaces having slight variations in optical properties, representative of those found in operating process lines. We demonstrate that linewidth uniformity of the developed photoresist can be greatly improved when the intensity of diffracted light from the latent image is used to control the exposure dose. Samples include a variety of photoresist materials and substrates with a wide range of optical properties. To verify the experimental observations, diffractions from the latent image grating structures are modeled using rigorous coupled wave analysis. 17 refs., 13 figs.

• OSTI ID: 5038903
• Journal Information: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States), Vol. 10:5; ISSN 0734-211X
• Country of Publication: United States
• Language: English

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PRINTED CIRCUITS
FABRICATION
VISIBLE RADIATION
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LASERS
LINE WIDTHS
MASKING
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COHERENT SCATTERING
ELECTROMAGNETIC RADIATION
ELECTRONIC CIRCUITS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
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