Measurement of lateral diffusion of diffused layers
First Claim
1. A method for evaluating a semiconductor wafer, the method comprising:
- forming a test structure of a predetermined geometry in the semiconductor material, said test structure comprising a plurality of areas separated from one another, at least one area in the plurality of areas being either mostly doped or mostly undoped;
measuring light reflected from said test structure, said reflected light having a component from said at least one area; and
analyzing a signal obtained from measuring to determine the extent of lateral diffusion in said at least one area;
wherein said analyzing includes using a measurement of linewidth to calibrate out the effect of linewidth errors due to variation in lithographic process.
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Accused Products
Abstract
Any semiconductor wafer fabrication process may be changed to monitor lateral abruptness of doped layers as an additional step in the wafer fabrication process. In one embodiment, a test structure including one or more doped regions is formed in a production wafer (e.g. simultaneously with one or more transistors) and one or more dimension(s) of the test structure are measured, and used as an estimate of lateral abruptness in other doped regions in the wafer, e.g. in the simultaneously formed transistors. Doped regions in test structures can be located at regularly spaced intervals relative to one another, or alternatively may be located with varying spacings between adjacent doped regions. Alternatively or in addition, multiple test structures may be formed in a single wafer, with doped regions at regular spatial intervals in each test structure, while different test structures have different spatial intervals.
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Citations
16 Claims
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1. A method for evaluating a semiconductor wafer, the method comprising:
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forming a test structure of a predetermined geometry in the semiconductor material, said test structure comprising a plurality of areas separated from one another, at least one area in the plurality of areas being either mostly doped or mostly undoped;
measuring light reflected from said test structure, said reflected light having a component from said at least one area; and
analyzing a signal obtained from measuring to determine the extent of lateral diffusion in said at least one area;
wherein said analyzing includes using a measurement of linewidth to calibrate out the effect of linewidth errors due to variation in lithographic process. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for evaluating a semiconductor wafer, the method comprising:
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forming a test structure of a predetermined geometry in the semiconductor material, said test structure comprising a plurality of areas separated from one another, a first area in the plurality of areas being doped at a different concentration relative to a second area in the plurality of areas;
measuring light reflected from said test structure, spid reflected light having a component from at least one of the first area and the second area;
analyzing a signal obtained from measuring to determine the extent of lateral diffusion in said at least one of the first area and the second area;
wherein a first fraction of doping in said first area is known and a second fraction of doping in said second area is also known, and said analyzing includes using said first fraction and said second fraction to determine the extent of lateral diffusion. - View Dependent Claims (16)
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Specification