A method for forming a patterned mask layer is provided. The method includes forming a first layer over a substrate. The method includes forming a first strip structure and a second strip structure over the first layer. The method includes forming a spacer layer conformally covering the first strip structure, the second strip structure, and the first layer. The method includes forming a block structure in the first trench. The method includes removing a first portion of the spacer layer, which is under the first trench and not covered by the block structure, and a second portion of the spacer layer, which is over the first strip structure and the second strip structure. The method includes forming a third strip structure in the second trench and the third trench. The method includes removing the block structure. The method includes removing the spacer layer.

The present disclosure provides forming nanostructures utilizing multiple patterning process with good profile control and feature transfer integrity. In one embodiment, a method for forming features on a substrate includes forming a first mandrel layer on a material layer disposed on a substrate. A first spacer layer is conformally formed on sidewalls of the first mandrel layer, wherein the first spacer layer comprises a doped silicon material. The first mandrel layer is selectively removed while keeping the first spacer layer. A second spacer layer is conformally formed on sidewalls of the first spacer layer and selectively removing the first spacer layer while keeping the second spacer layer.

A method for forming fins includes forming a three-color hardmask fin pattern on a fin base layer. The three-color hardmask fin pattern includes hardmask fins of three mutually selectively etchable compositions. Some of the fins of the first color are etched away with a selective etch that does not remove fins of a second color or a third color and that leaves at least one fin of the first color behind. The fins of the second color are etched away. Fins are etched into the fin base layer by anisotropically etching around remaining fins of the first color and fins of the third color.

Provided is a method of high-density pattern forming, which includes: providing a substrate; forming a hard mask layer on the substrate; forming a sacrificial layer on the hard mask layer; forming photoresists arranged at intervals on the sacrificial layer; etching the sacrificial layer to enable the sacrificial layer to form a mandrel corresponding to the photoresist one by one, wherein a cross-sectional size of the mandrel gradually decreases from an end of the mandrel away from the hard mask layer to an end close to the hard mask layer; forming an isolation layer on the mandrel; removing the isolation layer on the top of the mandrel, the isolation layer covering the hard mask layer, and the mandrel to form an isolation sidewall pattern; and transferring the isolation sidewall pattern to the hard mask layer.

A method of forming a pitch pattern is provided. The method includes forming two adjacent mandrels separated by a first distance, D1, on a substrate, and forming a first set of alternating sidewall spacers between the two adjacent mandrels. The method further includes removing the two adjacent mandrels, and forming a second set of alternating sidewall spacers and a third set of alternating sidewall spacers on opposite sides of the first set of sidewall spacers.

Semiconductor structures and fabrication methods are provided. An exemplary fabrication method includes providing a to-be-etched layer; forming a first sacrificial film on the to-be-etched layer; and forming a plurality of discrete first sidewall spacers and sidewall trenches on the first sacrificial film. Each sidewall trench is located between two adjacent first sidewall spacers; the first sidewall trenches include a first sidewall trench and a second sidewall trench, and a width of the second sidewall trench is greater than that of the first sidewall trench. The method also includes forming a second sidewall spacer in the first sidewall trench to fill the first sidewall trench; and etching the first sacrificial film using the first sidewall spacers and the second sidewall spacer as an etching mask to form a plurality of discrete first sacrificial layers on the to-be-etched layer.

The present application relates to a semiconductor fin structure cut process. The process includes: providing a semiconductor substrate and forming a plurality of fin structures on the semiconductor substrate, a gap being formed between every two adjacent fin structures; depositing a first dielectric layer, the first dielectric layer being filled in the gaps so that all fin structures are connected into a whole to form a semiconductor with fins; forming a plurality of pattern layer strips on the semiconductor with fins, a groove being formed between every two adjacent pattern layer strips, the fin structures closest to each pattern layer strip in the semiconductor with fins being necessary fin structures, attaching mask strips onto side surfaces of each pattern layer strip, the mask strips covering the necessary fin structures; etching the semiconductor with fins so that the unnecessary fin structures not covered by the mask strips are truncated.

A method includes depositing a hard mask over a target layer. Depositing the hard mask includes depositing a first hard mask layer having a first density and depositing a second hard mask layer over the first hard mask layer, the second hard mask layer having a second density greater than the first density. The method further includes forming a plurality of mandrels over the hard mask; depositing a spacer layer over and along sidewalls of the plurality of mandrels; patterning the spacer layer to provide a plurality of spacers on the sidewalls of the plurality of mandrels; after patterning the spacer layer, removing the plurality of mandrels; transferring a patterning the plurality of spacers to the hard mask; and patterning the target layer using the hard mask as a mask.

A method for cutting off a fin in a field effect transistor, comprising: step 1: forming fins and first spacing regions, there are two types of fins—the first type is configured to be cut off and a second type is configured to be reserved; and forming a first material layer to fill the first spacing regions; step 2: forming a first pattern structure comprising first strip structures aligning to one first type fin and second spacing regions; step 3: forming second sidewalls on two sides of each first strip structure; step 4: removing the first strip structures to form a second pattern structure by the second sidewalls; step 5: etching away the first material layer and the first type of fins by using the second sidewalls as a mask ; step 6: removing the second sidewalls and the remaining first material layer. The present application enables using less advanced lithography equipment.

A method for fabrication of a semiconductor structure according to some embodiments of the present disclosure comprises following steps. A first mandrel is formed over a target layer over a substrate, wherein the first mandrel comprises a mandrel island connecting a first mandrel strip and a second mandrel strip. A first spacer is formed along first and second sidewalls of the mandrel island, the first mandrel strip, and the second mandrel strip. The first mandrel is then removed, and the target layer is patterned with the first spacer remains over the target layer. The first mandrel strip and the second mandrel strip are misaligned from one another.