Abstract: An IC manufacturing method includes forming first mandrels and second mandrels over a substrate; and forming first spacers on sidewalls of the first mandrels and second spacers on sidewalls of the second mandrels. Each of the first and second spacers has a loop structure with two curvy portions connected by two lines. The method further includes removing the first and second mandrels; and removing the curvy portions from each of the first spacers without removing the curvy portions from the second spacers. The second spacers are used for monitoring variations of the IC fabrication processes.

Abstract: An IC manufacturing method includes forming first mandrels and second mandrels over a substrate; and forming first spacers on sidewalls of the first mandrels and second spacers on sidewalls of the second mandrels. Each of the first and second spacers has a loop structure with two curvy portions connected by two lines. The method further includes removing the first and second mandrels; and removing the curvy portions from each of the first spacers without removing the curvy portions from the second spacers. The second spacers are used for monitoring variations of the IC fabrication processes.

Abstract: An IC manufacturing method includes forming first mandrels and second mandrels over a substrate; and forming first spacers on sidewalls of the first mandrels and second spacers on sidewalls of the second mandrels. Each of the first and second spacers has a loop structure with two curvy portions connected by two lines. The method further includes removing the first and second mandrels; and removing the curvy portions from each of the first spacers without removing the curvy portions from the second spacers. The second spacers are used for monitoring variations of the IC fabrication processes.

Abstract: An IC manufacturing method includes forming first mandrels and second mandrels over a substrate; and forming first spacers on sidewalls of the first mandrels and second spacers on sidewalls of the second mandrels. Each of the first and second spacers has a loop structure with two curvy portions connected by two lines. The method further includes removing the first and second mandrels; and removing the curvy portions from each of the first spacers without removing the curvy portions from the second spacers. The second spacers are used for monitoring variations of the IC fabrication processes.

Abstract: Each of a plurality of data items is stored in a table data structure. A row identifier and column identifier are associated with each respective data item, and each respective item is stored at a logical location in the table data structure specified by its row identifier and column identifier. A plurality of data items is stored in a cell of the table data structure, and a timestamp is associated with each of the plurality of data items stored in the cell. Each of the data items stored in the cell has the same row identifier, the same column identifier, and a distinct timestamp. In some embodiments, each row identifier is a string of arbitrary length and arbitrary value. Similarly, in some embodiments each column identifier is a string of arbitrary length and arbitrary value.