Abstract: The invention relates to a method of photolithography comprising the steps of: providing a substrate and forming a layer of a photoresist on the substrate, performing a first exposure in which a predetermined part of the layer of photoresist is irradiated through a mask having a pattern for forming a latent image of said pattern in the layer of the photoresist, performing a pretreatment on the layer of the photoresist to remove a predetermined part of the latent image before performing the fixation. The method provides an improved process window. The invention further relates to a photoresist for use within the method of the invention.

Abstract: A method of irradiating to pattern a photosensitive layer such as a resist (L2) immersed in a fluid (L3), involves applying a removable transparent layer (L4, L5), projecting the radiation onto the resist through the immersion fluid and through the transparent layer, such that imperfections in the fluid are out of focus as projected on the surface, and subsequently removing the transparent layer. The transparent layer can help distance such imperfections from the focus of the radiation on the surface and so can reduce or eliminate shadowing. Hence the irradiation can be more complete, and defects reduced. It can be particularly effective for imperfections in the form of small bubbles or particles in the immersion fluid especially at the fluid/surface interface for example. The radiation can be for any purpose including inspection, processing, patterning and so on. The removal of the transparent layer can be combined with a step of developing the resist layer.

Abstract: The present invention provides a method of lithographic patterning. The method comprises: applying to a surface to be patterned a photoresist (18) comprising a polymer resin, a photocatalyst generator which generates a catalyst on exposure to actinic radiation, and a quencher; exposing the photoresist (18) to actinic radiation through a mask pattern (12); carrying out a post-exposure bake; and then developing the photoresist (18) with a developer to remove a portion of the photoresist which has been rendered soluble in the developer. Either the polymer resin is substantially insoluble in the developer prior to exposure to actinic radiation and rendered soluble in the developer by the action of the catalyst, and by the action of the quencher during the bake, or the polymer resin is soluble in the developer prior to exposure to actinic radiation and rendered substantially insoluble in the developer by the action of the catalyst, and by the action of the quencher during the bake.

Abstract: The present invention provides a method of lithographic patterning in order to the strength of the patterned photoresist. The method comprises: applying to a surface to be patterned a photoresist (18) comprising a polymer resin, a photocatalyst generator which generates a catalyst on exposure to actinic radiation, and a quencher; and exposing the photoresist (18) to actinic radiation through a mask pattern (12). This is followed, in either order, by carrying out a post-exposure bake; and developing the photoresist (18) with a developer to remove a portion of the photoresist which has been exposed to the actinic radiation. The polymer resin is substantially insoluble in the developer prior to exposure to actinic radiation and rendered soluble in the developer by the action of the catalyst, and wherein the polymer resin is crosslinked by the action of the quencher during the bake.

Abstract: A method of achieving frequency doubled lithographic patterning is described. An optical pattern (16) having a first period (p1) is used to expose conventional acid-catalysed photoresist (18) on substrate (20), leaving regions of high exposure (24), regions of low exposure (26) and intermediate regions (22). Processing proceeds leaving regions (24) which received high exposure very polar, i.e. hydrophilic, regions (26) of low exposure very apolar, i.e. hydrophobic, and the intermediate regions having intermediate polarity. A developer of intermediate polarity such as propylene glycol methyl ether acetate is then used to dissolve only the intermediate regions (22) leaving photoresist patterned to have a pitch (p2) half that of the optical period (p1). Alternatively, the photoresist is removed from the apolar and polar regions leaving only the intermediate regions (22) again with the same pitch (p2) half that of the optical period (p1).

Abstract: In a method for evaluating the polarization state of an illumination system (52) in an optical system (50), a mask (56) is provided in the optical system (50) such that an illumination beam incident on the mask (56) is adapted such as to substantially differently diffract incident components of a light beam having different polarization states. An image of the mask (56) is then obtained, using an illumination beam of the illumination system (52) of the optical system (50). The obtained image, being either an intensity plot or a structure created in a resist layer by exposing the resist layer with the image of the mask (56), is then used to extract polarization related information about the illumination system (52). The image used for evaluating may be a diffraction image of the mask.

Abstract: The present invention provides a method of lithographic patterning. The method comprisese: applying to a surface to be patterned a photoresist (18) comprising a polymer resin, a photocatalyst generator which generates a catalyst on exposure to actinic radiation, and a quencher; exposing the photoresist (18) to actinic radiation through a mask pattern (12); carrying out a post-exposure bake; and then developing the photoresist (18) with a developer to remove a portion of the photoresist which has been rendered soluble in the developer. Either the polymer resin is substantially insoluble in the developer prior to exposure to actinic radiation and rendered soluble in the developer by the action of the catalyst, and by the action of the quencher during the bake, or the polymer resin is soluble in the developer prior to exposure to actinic radiation and rendered substantially insoluble in the developer by the action of the catalyst, and by the action of the quencher during the bake.

Abstract: The present invention provides a method of lithographic patterning in order to the strength of the patterned photoresist. The method comprises: applying to a surface to be patterned a photoresist (18) comprising a polymer resin, a photocatalyst generator which generates a catalyst on exposure to actinic radiation, and a quencher; and exposing the photoresist (18) to actinic radiation through a mask pattern (12). This is followed, in either order, by carrying out a post-exposure bake; and developing the photoresist (18) with a developer to remove a portion of the photoresist which has been exposed to the actinic radiation. The polymer resin is substantially insoluble in the developer prior to exposure to actinic radiation and rendered soluble in the developer by the action of the catalyst, and wherein the polymer resin is crosslinked by the action of the quencher during the bake.

Abstract: A method of achieving frequency doubled lithographic patterning is described. An optical pattern (16) having a first period (p1) is used to expose conventional acid-catalysed photoresist (18) on substrate (20), leaving regions of high exposure (24), regions of low exposure (26) and intermediate regions (22). Processing proceeds leaving regions (24) which received high exposure very polar, i.e. hydrophilic, regions (26) of low exposure very apolar, i.e. hydrophobic, and the intermediate regions having intermediate polarity. A developer propylene glycol methyl ether acetate is then used to dissolve only the intermediate regions (22) leaving photoresist patterned to have a pitch (p2) half that of the optical period (p1). Alternatively, the photoresist is removed from the apolar and polar regions leaving only the intermediate regions (22) again with the same pitch (p2) half that of the optical period (p1).

Abstract: A method of irradiating to pattern a photosensitive layer such as a resist (L2) immersed in a fluid (L3), involves applying a removable transparent layer (L4, L5), projecting the radiation onto the resist through the immersion fluid and through the transparent layer, such that imperfections in the fluid are out of focus as projected on the surface, and subsequently removing the transparent layer. The transparent layer can help distance such imperfections from the focus of the radiation on the surface and so can reduce or eliminate shadowing. Hence the irradiation can be more complete, and defects reduced. It can be particularly effective for imperfections in the form of small bubbles or particles in the immersion fluid especially at the fluid/surface interface for example. The radiation can be for any purpose including inspection, processing, patterning and so on. The removal of the transparent layer can be combined with a step of developing the resist layer.

Abstract: A method of monitoring a photolithographic process whereby a test pattern (4) is imaged a number of times side by side with the same radiant energy on a photoresist layer (1) provided on a surface (2) of a substrate (3), but in a series of different irradiation times, after which the photoresist is developed. The irradiation dose or "energy-to-clear" with which the photoresist becomes just soluble in developer can thus be ascertained. The radiant energy with which the test pattern is imaged on the photoresist is only a fraction here of the radiant energy available in the process itself for imaging patterns on photoresist which is to be monitored. The method is thus suitable for monitoring a photolithographic process in which pulsed laser radiation is used for the pattern irradiation. The energy-to-clear can be accurately determined also in these processes.