Monitoring pattern for devices
View Patent ↗Reticle and methods for forming a device or reticle are presented. A reticle is provided with a device pattern and a first monitoring pattern. The first monitoring pattern includes a plurality of first test cells having a first test cell area and a first test pattern. The first test cells have different first pitch ratios to an anchor pitch and the first test pattern fills the first test cell area of a first test cell. A wafer with a resist layer is exposed with a lithographic system using the reticle. The resist is developed to form a patterned resist layer on the wafer and the wafer is processed using the patterned resist layer.
1. A method of forming a device comprising:
providing a reticle with a device pattern and a first monitoring pattern, wherein the first monitoring pattern includes a set of first test cells having plurality of first test cells, each of the first test cell comprises a first test cell area and a first test pattern, wherein
the first test cell area is the same for each of the first test cell,
the first test pattern is the same type of test pattern except that the first test patterns of different first test cells have different pitch ratios with respect to an anchor pitch, and
the first test pattern occupies the first test cell area of each of the first test cell;
exposing a wafer with a resist layer with a lithographic system using the reticle;
developing the resist to form a patterned resist layer on the wafer; and
processing the wafer using the patterned resist layer.
2. The method of claim 1 wherein the first test pattern comprises a line pattern with line features separated by spaces.
3. The method of claim 2 wherein first test cells include:
a first sub-group of test cells with the first test pattern; and
a second sub-group of test cells with a negative first test pattern (negative test cells).
4. The method of claim 3 wherein the first test cells comprise a minimum of 16 pitch ratio to the anchor pitch, with the first sub-group comprising 10 test cells and the second sub-group comprising 6 negative test cells.
5. The method of claim 1 wherein the first test pattern comprises a via pattern with via features.
6. The method of claim 5 wherein the first test cells comprise a minimum of 10 pitch ratio to the anchor pitch.
7. The method of claim 1 wherein the first test pattern comprises a line pattern with line features.
8. The method of claim 7 wherein the first test pattern comprises a minimum of 16 pitch ratio to the anchor pitch.
9. The method of claim 1 wherein the reticle comprises:
a prime region in which features corresponding to the device are formed;
a frame region surrounding the prime region, the prime region and frame region form a scanner region of the photolithographic system; and
an external region surrounding the prime region, the external region forms a non-scanner region of the photolithographic system, wherein the external region includes
a pellicle region surrounding the frame region, and
a non-pellicle region surrounding the pellicle region.
10. The method of claim 9 wherein the non-pellicle region comprises:
a reticle monitoring pattern, wherein the reticle monitoring pattern includes a plurality of reticle test cells having a reticle test cell area and a reticle test pattern, wherein
the reticle test cell area is the same for each of the plurality of reticle test cells,
the reticle test pattern for the different reticle test cells is the same except that the reticle test patterns of different reticle test cells have different pitch ratios with respect to a reticle anchor pitch, and
the reticle test pattern fills the reticle test cell area of each of the reticle test cells.
11. The method of claim 10 , wherein the reticle comprises:
a second monitoring pattern, wherein the second monitoring pattern includes a plurality of second test cells having a second test cell area and a second test pattern, wherein
the second test cell area is the same for each of the plurality of second test cells,
the second test pattern is the same type of test pattern except that the second test patterns of different first second cells have different pitch ratios with respect to the anchor pitch, and
the second test pattern fills the second test cell area of each of the second test cells;
the first and second monitoring patterns are disposed on a frame region of the reticle;
monitoring the second test pattern for reticle proximity monitoring during fabrication of the device; and
wherein the second test pattern is different from the first test pattern.
12. The method of claim 1 wherein first test pattern approximates the density variation of the real production-device.
13. The method of claim 1 wherein the first monitoring pattern comprises critical dimension to pitch (CDTP) ratios to the anchor pitch which-approximate the density of a SRAM device.