Field effect transistor monitors
First Claim
1. A monitoring system for determining channel widths comprising,a semiconductor substrate having a first conductivity region and first and second parallel strips of a second conductivity disposed at one surface thereof within said first conductivity region,a first conductive strip having a nominal width and a second conductive strip having a nominal width arranged parallel to each other and extending between said first and second parallel strips for forming first and second conductive channels, respectively, in said first conductivity region,a thin dielectric medium interposed between said conductive strips and said substrate,means for selectively applying a first voltage between said first conductive strip and said first parallel strip and for selectively applying a second voltage between said second conductive strip and said first parallel strip, andmeans for measuring current flow in said second parallel strip upon application of said first voltage and upon application of said second voltage to determine in relationship with the nominal width of at least one of said conductive strips the widths of said first and second channels.
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Accused Products
Abstract
Method and apparatus for measuring or determining characteristics, such as the actual effective width of a first conductive medium of a given design width produced by an integrated circuit process. The first conductive medium is formed apart from and parallel to a second and similar conductive medium of a given design width on an insulating medium which is disposed on a semiconductor substrate. The substrate has a first conductivity region and first and second parallel strips of a second and opposite conductivity disposed at one surface thereof within the first conductivity region for forming a channel of a given length. The first and second conductive media are arranged orthogonal to the first and second strips. A first voltage is applied between the first conductive medium and the first parallel strip and a second voltage is applied between the second conductive medium and the first parallel strip. Current is measured in the second parallel strip upon application of the first voltage and upon application of the second voltage. The actual or effective widths of the first and second conductive media are then determined by utilizing relationships between the measured currents and known constants, such as the design widths of the conductive media. In one embodiment, the etch bias of the conductive media may be obtained by forming the first and second media with different design widths. In another embodiment, the precision of alignment of an element at one level with an element at another level may be obtained by providing first and second parallel edges of a channel at one level and disposing at another level an edge of each of the first and second conductive media over the channel and parallel to the edges of the channel.
22 Citations
10 Claims
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1. A monitoring system for determining channel widths comprising,
a semiconductor substrate having a first conductivity region and first and second parallel strips of a second conductivity disposed at one surface thereof within said first conductivity region, a first conductive strip having a nominal width and a second conductive strip having a nominal width arranged parallel to each other and extending between said first and second parallel strips for forming first and second conductive channels, respectively, in said first conductivity region, a thin dielectric medium interposed between said conductive strips and said substrate, means for selectively applying a first voltage between said first conductive strip and said first parallel strip and for selectively applying a second voltage between said second conductive strip and said first parallel strip, and means for measuring current flow in said second parallel strip upon application of said first voltage and upon application of said second voltage to determine in relationship with the nominal width of at least one of said conductive strips the widths of said first and second channels.
Specification