Box-in-box field-to-field alignment structure
View Patent ↗A lithographic pattern includes a first scribe along an edge of a die region, and a second scribe along an opposing edge of the die region. The first scribe includes at least a first translucent box and a second translucent box. The second scribe includes at least a first opaque box and a second opaque box defined respectively by a first translucent frame and a second translucent frame. When the lithographic pattern is stepped between fields on a wafer, the first translucent box is placed at least partially within the first opaque box, and the second translucent box is placed at least partially within the second opaque box. If a continuous ring is formed from a pair of a translucent box and an opaque box, the fields are aligned at least within an amount equal to the difference between the dimensions of that translucent box and that opaque box divided by 2.
1. A method for determining field-to-field alignment, comprising:
exposing a first scribe pattern from a mask on a resist over a scribe lane between a first field and a second field on a wafer, wherein the first scribe pattern comprises:
a first outer pattern of a first transmission characteristic defined by a first frame pattern of a second transmission characteristic;
a second outer pattern of the first transmission characteristic defined by a second frame pattern of the second first transmission characteristic, wherein the first frame pattern comprises a smaller inner perimeter and a smaller outer perimeter than the second frame pattern;
stepping the mask from the first field to the second field;
exposing a second scribe pattern from the mask on the resist over the scribe lane, wherein the second scribe pattern comprises:
a first inner pattern of the second transmission characteristic;
a second inner pattern of the second transmission characteristics, wherein the first inner pattern and the second inner pattern comprise equal outer perimeters;
developing portions of the resist over the scribe exposed according to the first outer pattern, the first inner pattern, the second outer pattern, and the second inner pattern; and
etching the scribe to form (1) a first ring from the first outer pattern and the first inner pattern, and (2) a second ring from the second outer pattern and the second inner pattern.
2. The method of claim 1 , further comprising determining if the first ring is continuous, wherein the mask is aligned within a critical dimension if the first ring is continuous.
3. The method of claim 2 , further comprising determining if the second ring is continuous, wherein the mask is aligned within a predetermined dimension larger than the critical dimension if the second ring is continuous.
4. The method of claim 1 , further comprising determining if the second ring is continuous, wherein the mask is aligned within a critical dimension if the second ring is continuous.
5. The method of claim 4 , further comprising determining if the first ring is continuous, wherein the mask is aligned within a predetermined dimension smaller than the critical dimension if the first ring is continuous.