Order of Reaction between Photoresist and Atomic Hydrogen Generated by a Tungsten Hot-Wire Catalyst

Abstract

This paper clarifies the reaction order of photoresist removal using atomic hydrogen by investigating the relationship between atomic hydrogen density (nH) and photoresist removal rate (vrmv). Atomic hydrogen was generated by decomposing hydrogen molecules with a tungsten hot-wire catalyst. In the reaction between atomic hydrogen and photoresist, we found that vrmv increases in direct proportion to nH and revealed that the reaction exhibited a first-order kinetics with respect to nH.

Enhancement of Photoresist Removal Rate by Using Atomic Hydrogen Generated under Low-pressure Conditions

“…Some findings related to the use of atomic hydrogen generated on a tungsten hot-wire catalyst for photoresist removal have already been reported [10][11][12][13][14][15][16]. In a past study we achieved a best removal rate of 2.5 μm/min using atomic hydrogen by heating up the catalyst and the substrate [12].…”

Pressure Dependence of Photoresist Removal Rate Using Hydrogen Radicals

“…The removal rate is obtained from the change in the film thickness per unit time. The removal rate increases in proportion to the density when the pressure is constant [10]. According to Umemoto et al [13], the density of hydrogen radical increases proportionally to the square root of H 2 pressure.…”

“…Some findings related to the use of hydrogen radicals produced on a tungsten hot-wire catalyst for photoresist removal have already been reported [7][8][9][10][11][12]. In general, the catalyst and the substrate are heated to enhance the removal rate, but limitations do exist.…”

“…However, the density of hydrogen radical decreases concomitantly with decreasing pressure because the density decreases in proportion to the square root of hydrogen pressure [13]. Furthermore, the removal rate increases proportionally to the density [10]. Therefore, the removal rate is expected to increase concomitantly with decreasing pressure, but it attains the upper limit and then decreases.…”

Stripping of the Positive-tone Diazonaphthoquinone / Novolak Resist using Laser Irradiation from Visible to Near Infrared Wavelength

“…The resist is decomposed into -CxHy and -OH by atomic hydrogen, which is generated by contact catalysis on a hot-wire catalyzer [16][17][18][19]. This method, which is a dry method without plasma, is expected to reduce costs and environmental damage.…”