Method for manufacturing a semiconductor product wafer
Improved methods for manufacturing semiconductor product wafer with the additional use of non-product masks are described. According to certain aspects of the invention, an evaluation wafer is first manufactured by utilizing at least one non-product mask to process one or more layer(s) on the evaluation wafer, and subsequently utilizing at least one unaltered product mask to process an evaluation-region-of-interest on the evaluation wafer. The evaluation-region-of-interest is evaluated by measuring the state of one or more feature(s) in the evaluation-region-of-interest using voltage contrast inspection (VCi). The measurements are then used to identify failures in the evaluation-region-of-terest. In response to identifying a failure in the evaluation-region-of-interest, the manufacturing process is improved by modifying at least one parameter associated with at least one processing step and manufacturing product wafers utilizing the at least one processing step(s) with the at least one modified parameter(s).
1. A method for manufacturing a semiconductor product wafer, said product wafer defined by a series of product masks employed in a series of mask-enabled processing steps, said manufacturing method comprising at least the following steps:
(i) manufacturing an evaluation wafer by:
(a) utilizing at least one non-product mask to process one or more layer(s) on the evaluation wafer by producing e-beam pads and connecting them with one or more feature(s) in an evaluation-region-of-interest of the evaluation wafer; and
(b) subsequently utilizing at least one unaltered product mask to process the evaluation-region-of-interest on the evaluation wafer;
(ii) evaluating the evaluation-region-of-interest by:
(a) measuring a state of one or more feature(s) in the evaluation-region-of-interest using voltage contrast inspection (VCi);
(b) using measurement(s) from (ii) (a) to identify failures in the evaluation-region-of-interest;
(iii) in response to step (ii)(b), improving the manufacturing process by:
(a) modifying at least one parameter associated with at least one processing step; and,
(v) manufacturing product wafers utilizing the at least one processing step(s) with the at least one modified parameter(s).
2. The method of claim 1 further comprising identifying failures in the evaluation-region-of-interest, including:
identifying failures in the evaluation-region-of-interest that are observable with use of the non-product mask; and
identifying at least some failures in the evaluation-region-of-interest that are unobservable without use of the non-product mask.
3. The method of claim 2 wherein the failures identified in the evaluation-region-of-interest are unobservable even when directly scanned with a same e-beam spot size as was used to measure the state of the one or more feature(s) in the evaluation-region-of-interest.
4. The method of claim 1 wherein measuring the state of one or more feature(s) in the evaluation-region-of-interest of the evaluation wafer comprises determining whether the e-beam pads are charged or discharged.
5. The method of claim 1 wherein measuring the state of one or more feature(s) in the evaluation-region-of-interest of the evaluation wafer comprises determining brightness level of the e-beam pads.
6. The method of claim 1 further comprising scanning the one or more e-beam pads at a low resolution to determine whether at least one of the pads is charged.
7. The method of claim 1 wherein measuring the state of the one or more feature(s) in the evaluation-region-of-interest further comprises inferring leakage or resistance to ground from the measured charge or discharge state of the e-beam pads.
8. The method of claim 1 wherein measuring the state of one or more feature(s) in the evaluation-region-of-interest further comprises inferring leakage or resistance between e-beam pads by comparing a measured charge or discharge state of the e-beam pads.
9. The method of claim 1 wherein measuring the state of one or more feature(s) in the evaluation-region-of-interest comprises determining a non-binary value indicative of the measured charge or brightness of the e-beam pads.
10. A method for manufacturing a wafer for a semiconductor product, the semiconductor product formed using a series of product masks employed in a series of mask-enabled processing steps, the method comprising:
processing one or more layers of an evaluation wafer for the semiconductor product, the processing of the evaluation wafer including:
utilizing a non-product mask to process the one or more layers on the evaluation wafer to produce e-beam pads on the evaluation wafer and to connect the e-beam pads to one or more features in an evaluation-region-of-interest on the evaluation wafer; and
continuing processing the one or more layers of the evaluation wafer utilizing an unaltered product mask; and
identifying failures in the evaluation wafer by measuring a state of one or more features in the evaluation-region-of-interest using voltage contrast inspection (VCi);
modifying at least one parameter associated with at least one processing step; and
processing the semiconductor product utilizing the at least one modified parameter.