System for Directional Scan Access and Method for Directional Scan Testing Thereof

A method for scan signal rerouting in a semiconductor system including a plurality of dies arranged on a substrate, the method comprising:

• receiving, at a first die, scan data and control signals from at least one neighboring die;
• receiving, at the first die, scan clock signals from the at least one neighboring die;
• selecting, at the first die, one of the scan data and control signals as an input to a core using a first multiplexer;
• selecting, at the first die, one of the scan clock signals as a clock input to the core using a clock multiplexer;
• performing scan test operations in the core using the selected scan data, control, and clock signals;
• generating scan output signals from the core;
• selecting, based on test configuration, one of a plurality of scan output paths from the core;
• and
• rerouting the scan output signals to an alternative output direction when a default output path is unavailable.

A method of operating a semiconductor system including a plurality of dies arranged on a substrate, each die including a core, a scan multiplexer, a clock multiplexer, and a plurality of scan input and output paths, the method comprising:

• receiving a scan input signal and a scan clock signal at a first die of the plurality of dies from a neighboring die in a first direction;
• selecting, via a scan multiplexer and a clock multiplexer of the first die, the scan input signal and the scan clock signal, respectively;
• forwarding the selected scan input signal and the selected scan clock signal across a sequence of intermediate dies in a forward scan direction;
• routing the scan input signal and the scan clock signal to a target die located at an end of the sequence;
• reversing the direction of signal propagation from the target die;
• returning the scan input signal and the scan clock signal from the target die to the first die in a reverse scan direction;
• and
• observing, at the first die, a scan output signal in a same scan clock cycle in which the scan input signal was received, thereby reducing clock skew in the roundtrip scan path.