SEMICONDUCTOR STRUCTURES
Test structures are formed during semiconductor processing with a single mask that is used in a manner that also allows alignment marks to be formed which do not interfere with one another as subsequent layers are patterned. The test structures can provide insight into performance characteristics of different types of devices as the semiconductor process proceeds.
1 . A semiconductor structure, comprising:
a first instance of a reference mark in a first layer coincident with a first instance of a target reference mark in a first underlaying layer; and
a second instance of the reference mark in a second layer coincident with a second instance of the target reference mark in the first underlaying layer and not aligned with the first instance of the reference mark.
2 . The structure of claim 1 , comprising:
a third instance of the reference mark in the second layer aligned with the first instance of the reference mark in the first layer.
3 . The structure of claim 2 , the third instance of the reference mark coincident with the first instance of the target reference mark.
4 . The structure of claim 1 , comprising a test structure in the first layer.
5 . The structure of claim 1 , comprising a test structure in the second layer.
6 . The structure of claim 1 , comprising a first test structure in the first layer and a second test structure in the second layer.
7 . The structure of claim 1 , the first layer comprising polysilicon.
8 . The structure of claim 1 , the first layer formed to a thickness of between about 100 nanometers and about 400 nanometers.
9 . The structure of claim 7 , the first layer formed to a thickness of between about 100 nanometers and about 400 nanometers.
10 . The structure of claim 1 , the second layer comprising metal oxide.
11 . The structure of claim 1 , the second layer formed to a thickness of between about 1 nanometer and about 10 nanometers.
12 . The structure of claim 10 , the second layer formed to a thickness of between about 1 nanometer and about 10 nanometers.
13 . The structure of claim 1 , the first layer comprising polysilicon formed to a thickness of between about 100 nanometers and about 400 nanometers and the second layer comprising metal oxide formed to a thickness of between about 1 nanometer and about 10 nanometers.
14 . The structure of claim 6 , the first and second test structures aligned with one another.
15 . The structure of claim 1 , the second layer overlying the first layer.
16 . The structure of claim 1 , comprising:
a first pattern in the first layer comprising at least one feature corresponding to a first test structure; and
a second pattern in the second layer comprising at least one feature corresponding to a second test structure.
17 . The structure of claim 16 , the first layer comprising polysilicon formed to a thickness of between about 100 nanometers and about 400 nanometers and the second layer comprising metal oxide formed to a thickness of between about 1 nanometer and about 10 nanometers.
18 . A semiconductor structure, comprising:
a first instance of a reference mark in a first layer coincident with a first instance of a target reference mark in a first underlaying layer;
a second instance of the reference mark in a second layer coincident with a second instance of the target reference mark in the first underlaying layer and not aligned with the first instance of the reference mark;
a first test structure in the first layer; and
a second test structure in the second layer and aligned with the first test structure.
19 . A semiconductor structure comprising:
a substrate having a first instance of a target reference mark and a second instance of the target reference mark;
a first layer formed over the substrate and having a first instance of a reference mark and a first test structure, the first instance of the reference mark coincident with the first instance of the target reference mark; and
a second layer formed over the first layer and having a second instance of the reference mark and a second test structure, the second instance of the reference mark coincident with the second instance of the target reference mark and not aligned with the first instance of the reference mark.
20 . The structure of claim 19 , the first and second test structures aligned with one another.