Semiconductor wafer cooling
A cooling controller receives, from one or more sensors, wafer information associated with a wafer. The cooling controller determines a pattern mask area for the wafer based on the wafer information. The cooling controller determines a cooling time for the wafer based on the pattern mask area. The cooling controller causes a cooling plate to cool the wafer for a time duration equal to the cooling time. Determining the cooling time for a wafer based on a pattern mask area provides stable and consistent wafer temperatures for wafers having different mask and layout properties, which reduces mask overlay variation and increases wafer yield.
1. A method, comprising:
receiving, by a cooling controller, wafer information associated with a wafer from one or more sensors;
determining, by the cooling controller and based on the wafer information, a center point of the wafer,
wherein the center point of the wafer is based on a plurality of edge points for the wafer;
determining, by the cooling controller and based on the center point, a plurality of field edge points for the wafer,
wherein a quantity of the plurality of edge points is different from a quantity of the plurality of field edge points;
determining, by the cooling controller, a pattern mask area based on the plurality of field edge points;
determining, by the cooling controller, a cooling time for the wafer based on the pattern mask area and exposure process information; and
causing, by the cooling controller, a cooling plate to cool the wafer for a time duration equal to the cooling time.
2. The method of claim 1 , further comprising:
determining the plurality of edge points based on an image scan of the wafer.
3. The method of claim 1 , wherein the plurality of edge points are equally spaced apart along a perimeter of the wafer.
4. The method of claim 1 , wherein determining the center point comprises:
determining respective vectors from each edge point of the plurality of edge points; and
determining a point of intersection of the respective vectors as the center point.
5. The method of claim 1 , wherein determining the plurality of field edge points comprises:
determining a first vector from the center point; and
determining a second vector from the center point and orthogonal to the first vector.
6. The method of claim 1 , wherein determining the pattern mask area based on the plurality of field edge points comprises:
determining connecting lines between adjacent field edge points, of the plurality of field edge points, to form an enclosed area around the center point.
7. The method of claim 6 , wherein determining the pattern mask area based on the plurality of field edge points further comprises:
determining the pattern mask area based on a length and a width of the enclosed area.
8. A method, comprising:
coating a wafer with a photoresist;
determining a cooling time for the wafer by:
determining a time adjustment based on a scaling factor applied to a pattern mask area for the wafer; and
applying the time adjustment to a default cooling time;
causing a cooling plate to cool the wafer for a time duration equal to the cooling time;
exposing the wafer to a radiation source to transfer a pattern from a photomask to the photoresist; and
developing the pattern transferred to the photoresist on the wafer.
9. The method of claim 8 , further comprising:
determining the pattern mask area based on a center point of the wafer.
10. The method of claim 8 , wherein determining the cooling time comprises:
determining the cooling time based on a mask field utilization for the wafer.
11. The method of claim 8 , wherein the time duration equal to the cooling time is shorter in than a time duration equal to the default cooling time.
12. The method of claim 8 , wherein causing the cooling plate to cool the wafer for the time duration comprises:
transmitting a cooling control signal to the cooling plate at a start of the cooling time.
13. The method of claim 8 , wherein causing the cooling plate to cool the wafer for the time duration further comprises:
transmitting another cooling control signal to the cooling plate at an end of the cooling time.
14. The method of claim 8 , further comprising:
determining the pattern mask area based on a plurality of field edge points for the wafer.
15. A system, comprising:
one or more sensors configured to:
generate an image scan of a wafer, and
provide the image scan to a cooling controller;
the cooling controller configured to:
receive information indicating a presence of the wafer on a cooling plate;
provide, to the one or more sensors and based on the information indicating the presence of the wafer on the cooling plate, an indication to generate the image scan;
determine a plurality of field edge points for the wafer based on the image scan,
determine a pattern mask area for the wafer based on the plurality of field edge points,
determine a time adjustment based on the pattern mask area,
determine a cooling time for the wafer based on the time adjustment, and
provide a signal to the cooling plate based on the cooling time; and
the cooling plate configured to cool the wafer for a time duration equal to the cooling time based on the signal.
16. The system of claim 15 , further comprising:
a cooling plate sensor configured to detect the presence of the wafer on the cooling plate.
17. The system of claim 16 , wherein the cooling plate sensor is further configured to:
provide an indication of a temperature of the cooling plate to the cooling controller.
18. The system of claim 15 , wherein the cooling controller, to determine the cooling time, is configured to:
adjust a default cooling time using the time adjustment.
19. The system of claim 15 , wherein the cooling controller is further configured to:
provide another signal to the cooling plate to cause the cooling plate to stop cooling the wafer.
20. The system of claim 15 , wherein the cooling controller, to determine the time adjustment, is configured to:
determine the time adjustment based on a scaling factor applied to the pattern mask area.