Photoresist thickness selection peculiarities to ensure and improve the lithography process stability during semiconductor devices structures manufacturing

Аuthors

Tischenko L. A.^*, Kovalev A. A.^**, Markin A. V.^***

Bauman Moscow State Technical University, MSTU, 5, bldg. 1, 2-nd Baumanskaya str., Moscow, 105005, Russia

*e-mail: leonid.tichenko@gmail.com
**e-mail: kovalevarta@gmail.com
***e-mail: alexandr_markin_22@mail.ru

Abstract

Photolithography is one of the main technological processes for obtaining on a special base a certain topology of various electronic components. The most important thing herewith is minimization of all errors in the course of image transfer fr om a photomask to the photoresist layer, and at the developing stage. In this case the most accurate mage transfer is achieved.

The paper is devoted to a topical problem, namely to the photoresist thickness selection specifics to ensure and improve lithography process stability during semiconductor components structures manufacturing.

The paper describes the experimental study of the dependence of radiation energy (E0) dose, necessary to full structures' development in photoresist, from the photoresist thickness (h) on the example of SPR700-1.2 photoresist. The energy dose for the structures' full development in photoresist, determining the quantity of energy affecting the photoresist, required for full photoresist elimination from certain areas, determined by components' structures topologies is one of the basic technological parameters of photoresist.

In the course of the study one area per each of 33 silicon wafers were detected, wh ere the photoresist was completely removed. Radiation energy, at which the exposure of these areas was carried out, is an energy dose, necessary for the full structures' development in photoresist. Thus, the plot of energy dose, necessary for full structure development, versus photoresist thickness was obtained In the course of mathematical calculation, approximation of experimental harmonic dependence was performed and equation of the given curve was obtained.

Rational operating points (thickness) were determined using the plot obtained while experimental curve approximation. These points represent extremums, since with minimum deviation from the rated value, inherent to the considered operating point, the energy dose for full structure development in photoresist would vary insignificantly.

Thus, nine operating points corresponding to a certain photoresist thickness were obtained as the result of the approximated curve analysis.

The result of experimental study of radiation energy dose dependence from photoresist thickness described in this paper consists in obtaining of a number of recommended photoresist thicknesses, which observing can lead to the most accurate image transfer from photomask to photoresist layer, which, in its turn, will improve lithography process stability during semiconductor components structures manufacturing.

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Keywords:

photolithography, photoresist, development energy dose

References

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