Methods and techniques to use with photosensitized chemically amplified resist chemicals and processes
The disclosure herein describes methods for Photosensitized Chemically Amplified Resist Chemicals (PS-CAR) to pattern light sensitive films on a semiconductor substrate. In one embodiment, a two-step exposure process may generate higher acid concentration regions within a photoresist layer. The PS-CAR chemicals may include photoacid generators (PAGs) and photosensitizer elements that enhance the decomposition of the PAGs into acid. The first exposure may be a patterned EUV exposure that generates an initial amount of acid and photosensitizer. The second exposure may be a non-EUV flood exposure that excites the photosensitizer which increases the acid generation rate where the photosensitizer is located on the substrate. The distribution of energy during the exposures may be optimized by using certain characteristics (e.g., thickness, index of refraction, doping) of the photoresist layer, an underlying layer, and/or an overlying layer.
1. A method for treating a substrate, comprising:
receiving the substrate comprising an underlying layer on the substrate;
depositing a photoresist layer on the underlying layer,
wherein the underlying layer comprises:
an underlying layer index of refraction, and
an underlying layer thickness, and
wherein the photoresist layer comprises:
a first light wavelength activation threshold that controls a generation of acid to a first acid concentration in the photoresist layer; and
a second light wavelength activation threshold that increases the first acid concentration to a second acid concentration, the second light wavelength activation threshold being different from the first light wavelength activation threshold, and
wherein at least one of the underlying layer or the photoresist layer comprises a chromophore that limits light from reflecting off a surface of the underlying layer, the chromophore comprising a higher concentration at an interface of the photoresist layer and the underlying layer or proximate to a surface of the photoresist layer that is opposite the interface of the photoresist layer and the underlying layer than a concentration at a remaining portion of the underlying layer or the photoresist layer;
exposing a first wavelength of light through a patterned mask onto the substrate, and
exposing a second wavelength of light to the substrate, the second wavelength of light comprising a wavelength that is different from the first wavelength of light.
2. The method of claim 1 , wherein the chromophore comprises a carbon element and at least one or more of the following elements H, O, N, Cl, Br, S, or I.
3. The method of claim 1 , wherein the chromophore comprises a higher concentration at the interface of the photoresist layer and the underlying layer than the concentration at the remaining portion of the underlying layer or the photoresist layer.
4. The method of claim 1 , wherein the chromophore comprises a higher concentration proximate to the surface of the photoresist layer that is opposite the interface of the photoresist layer and the underlying layer.
5. The method of claim 1 , wherein the photoresist comprises:
a photosensitizer generation compound comprising:
acetophenone; triphenylene; benzophenone; fluorenone; anthraquinone; phenanthrene; or derivatives thereof; and
a photoacid generation compound comprising:
at least one of triphenylsulfonium triflate, triphenylsulfonium nonaflate, triphenylsulfonium perfluorooctylsulfonate, triarylsulfonium triflate, triarylsulfonium nonaflate, triarylsulfonium perfluorooctylsulfonate, a triphenylsulfonium salt, a triarylsulfonium salt, a triarylsulfonium hexafluoroantimonate salt, N-hydroxynaphthalimide triflate, 1,1-bis[p-chlorophenyl]-2,2,2-trichloroethane (DDT), 1,1-bis[p-methoxyphenyl]-2,2,2-trichloroethane, 1,2,5,6,9,10-hexabromocyclododecane, 1,10-dibromodecane, 1,1-bis[p-chlorophenyl]2,2-dichloroethane, 4,4-dichloro-2-(trichloromethyl)benzhydrol, 1,1-bis(chlorophenyl) 2-2,2-trichloroethanol, hexachlorodimethylsulfone, 2-chloro-6-(trichloromethyl)pyridine, or derivatives thereof.
6. The method of claim 1 , further comprising:
depositing a EUV top coat layer on the photoresist layer before exposing the first wavelength of light; and
developing the photoresist layer after exposing the second wavelength of light,
wherein exposing the first wavelength of light includes exposing the first wavelength of light onto the EUV top coat layer and the photoresist layer, the first wavelength of light comprising a wavelength in the EUV spectrum, and
wherein exposing the second wavelength of light includes exposing the second wavelength of light onto the EUV top coat layer, the second exposure being a blanket exposure of the substrate.
7. A method for treating a substrate, comprising:
receiving the substrate comprising an underlying layer on the substrate;
depositing a photoresist layer on the underlying layer, the photoresist layer comprising:
a first light wavelength activation threshold that controls a generation of acid to a first acid concentration in the photoresist layer; and
a second light wavelength activation threshold that increases the first acid concentration to a second acid concentration, the second light wavelength activation threshold being different from the first light wavelength activation threshold;
depositing a first top coat layer on the photoresist layer;
exposing a first range of light wavelengths through a patterned mask onto the first top coat layer and the photoresist layer;
removing the first top coat layer to expose the photoresist layer;
subsequent to removing the first top coat layer, exposing a second range of light wavelengths to the photoresist layer, the second exposure being a blanket exposure across the photoresist layer; and
developing the photoresist layer.
8. The method of claim 7 , wherein the first top coat layer prevents light with a wavelength of greater than 15 nm from reaching the photoresist layer.
9. The method of claim 8 , further comprising:
depositing a second top coat layer on to the photoresist layer following the removal of the first top coat layer.
10. The method of claim 9 , wherein the second top coat layer prevents light with a wavelength of less than 300 nm from reaching the photoresist layer.