Printing sublithographic images using a shadow mandrel and off-axis exposure

A method for defining a feature on a substrate, the method comprising the steps of:

• a. depositing a shadow mandrel laer on the substrate;
• b. etching a trough in the shadow mandrel layer, the trough having a sidewall and a bottom;
• c. depositing a layer of photoresist over the shadow mandrel layer and the trough, wherein the photoresist layer is a positive tone photoresist;
• d. exposing the photoresist layer at an angle such that the photoresist at a first portion of the trough bottom is exposed and the photoresist at a second portion of the trough bottom is blocked by the trough sidewall and unexposed;
• e. developing the photoresist layer;
• and
• f. defining the feature using the developed photoresist layer.

A method for defining a feature on a substrate, the method comprising the steps of:

• a. depositing a shadow mandrel layer on the substrate;
• b. etching a trough in the shadow mandrel layer, the trough having a sidewall and a bottom;
• c. depositing a layer of photoresist over the shadow mandrel layer and the trough, wherein the photoresist layer comprises a polysilane photoresist;
• d. exposing the photoresist layer at an angle such that the photoresist at a first portion of the trough bottom is exposed and the photoresist at a second portion of the trough bottom is blocked by the trough sidewall and unexposed;
• e. developing the photoresist layer;
• and
• f. defining the feature using the developed photoresist layer.

A method for defining a feature on a substrate, the method comprising the steps of:

• a. depositing a shadow mandrel laver on the substrate;
• b. etching a trough in the shadow mandrel layer, the trough having a sidewall and a bottom;
• c. depositing a layer of photoresist over the shadow mandrel layer and the trough, wherein the photoresist layer comprises polysilicon;
• d. exposing the photoresist layer at an angle such that the photoresist at a first portion of the trough bottom is exposed and the photoresist at a second portion of the trough bottom is blocked by the trough sidewall and unexposed;
• e. developing the photoresist layer;
• and
• f. defining the feature using the developed photoresist layer.

A method for defining a feature on a substrate, the method comprising the steps of:

• a. depositing a shadow mandrel layer on the substrate;
• b. etching a trough in the shadow mandrel layer, the trough having a sidewall and a bottom, wherein the trough extends along two axes;
• c. depositing a layer of photoresist over the shadow mandrel laver and the trough;
• d. exposing the photoresist layer at an angle such that the photoresist at a first portion of the trough bottom is exposed and the photoresist at a second portion of the trough bottom is blocked by the trough sidewall and unexposed, and wherein the step of exposing the photoresist further comprises exposing the photoresist at a non-perpendicular angle relative to the two axes of the trough such that the unexposed second portion of the trough bottom extends along two axes;
• e. developing the photoresist layer;
• and
• f. defining the feature using the developed photoresist layer.

A method for forming a feature on a semiconductor wafer comprising the steps of:

• a. depositing a layer of feature material over the surface of the semiconductor wafer;
• b. depositing a shadow mandrel layer over the layer of feature material;
• c. etching a trough having a bottom and sides through the shadow mandrel layer;
• d. applying a conformal photoresist layer over the shadow mandrel;
• e. exposing the photoresist layer using ion implantation such that at least one side of the trough casts a shadow at the bottom of the trough, the shadow being cast in a first portion of the trough bottom, the photoresist in the first portion thereby being unexposed while the remainder of the photoresist is exposed;
• f. developing the photoresist such that only the unexposed photoresist in the first portion of the trough bottom remains and the exposed photoresist is removed;
• g. removing the shadow mandrel layer;
• and
• h. removing the feature material from the surface of the wafer except at the first portion where the shadow was cast.

A method for forming a feature on a semiconductor wafer comprising the steps of:

• a. depositing a layer of feature material over the surface of the semiconductor wafer;
• b. depositing a memory layer over the layer of feature material;
• c. depositing a shadow mandrel layer over the memory layer;
• d. etching a trough having a bottom and sides through the shadow mandrel layer;
• e. applying a conformal layer of photoresist over the shadow mandrel layer and trough;
• f. exposing the photoresist using ion implantation such that at least one side of the trough casts a shadow at the bottom of the trough on a first portion of the photoresist, such that the first portion at the photoresist is unexposed while a second portion of the photoresist is exposed;
• g. developing the photoresist to remove the unexposed first portion of the photoresist;
• h. etching the memory layer underlying the first portion of the photoresist so as to form a depression in the memory layer corresponding to the unexposed first portion of the photoresist;
• i. removing the shadow mandrel layer;
• j. depositing an image reversal layer over the memory layer so as to fill the depression;
• k. removing the excess portions of the image reversal layer such that only a first portion of the image reversal layer remains in the depression;
• l. removing the memory layer;
• and
• m. forming the feature by removing the layer of feature material except where it underlies the remaining first portion of the image reversal layer.