Semiconductor device

Abstract

The disclosed invention provides a semiconductor device that enables early discovery of a sign of aged deterioration that occurs locally. An LSI has a plurality of modules and a delay monitor cluster including a plurality of delay monitors. Each delay monitor inducts a ring oscillator having a plurality of gate elements. Each delay monitor measures a delay time of the gate elements. A CPU #0 determines if a module proximate to a delay monitor suffers from aged deterioration, based on the delay time measured by the delay monitor.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 a plurality of modules;   a plurality of delay monitors, wherein each delay monitor includes a ring oscillator having a plurality of gate elements and measures a delay time of said gate elements, and   a control unit that whether or not the delay time measured by said delay monitor exceeds a predetermined reference value,   wherein, of said delay monitors, every two delay monitors disposed near to each other form one pair, wherein a ring oscillator in one delay monitor of said pair continues to oscillate except for a predetermined number of cycles before and after a delay time measurement period and a ring oscillator in the other delay monitor of said pair oscillates only during a delay time measurement period, and said control unit determines a difference between a delay time measured by said one delay monitor and a delay time measured by said other delay monitor.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein said control unit issues an alert, if having determined that said module suffers from aged deterioration. 
     
     
         3 . The semiconductor device according to  claim 1 , wherein said control unit performs a built-in self test of said semiconductor device, if having determined that said module suffers from aged deterioration. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein said control unit decreases the power supply voltage to the module proximate to said delay monitor, if having determined that said module suffers from aged deterioration. 
     
     
         5 . The semiconductor device according to  claim 1 , wherein said control unit decreases the operating frequency of the module proximate to said delay monitor, if having determined that said module suffers from aged deterioration. 
     
     
         6 . The semiconductor device according to  claim 1 , wherein said control unit increases the spinning speed or frequency of a fan disposed near to said delay monitor, if having determined that the module suffers from aged deterioration. 
     
     
         7 . The semiconductor device according to  claim 1 , wherein said semiconductor device includes the processors and said control unit, if having determined that said module suffers from aged deterioration, and when the module proximate to said delay monitor is a processor that executes a high load task, assigns said task to another processor. 
     
     
         8 . The semiconductor device according to  claim 1 , wherein said semiconductor device includes the processors, one of the processors serving as a main processor and the remaining processors serving as sub-processors, and said control unit, if having determined that said module suffers from aged deterioration, and when the module proximate to said delay monitor is a processor that serves as the main processor, changes the processor as said proximate module to serve as a sub-processor and changes a processor serving as a sub-processor to serve as the main processor. 
     
     
         9 . The semiconductor device according to  claim 1 , said processors have their respective Anthers IDs and changing a processor serving as a sub-processor to serve as the main processor is done by interchanging the identifiers IDs of the sub-processor and the processor serving as the main processor at that time. 
     
     
         10 . The semiconductor device according to  claim 1 , wherein said semiconductor device includes the processors, wherein a part of said processors can serve as a stand-by processor, and said control unit, if having determined that said module suffers from aged deterioration, and if the module proximate to said delay monitor is an active processor and when a processor serving as a stand-by processor is available, deactivates the processor as said proximate module and activates the processor serving as the stand-by processor. 
     
     
         11 . The semiconductor device according to  claim 1 , wherein said semiconductor device includes the processors, wherein a part of said processors can serve as a stand-by processor and parallel processing of programs can be carried out by two or more processors except for the stand-by processor, and said control unit, if having determined that said module suffers from aged deterioration, and when the module proximate to said delay monitor is an active processor and when a processor serving as a stand-by processor is not available, deactivates the processor as said proximate module. 
     
     
         12 . The semiconductor device according to  claim 1 , wherein the ring oscillator of said delay monitor continues to oscillate for a delay time measurement period and except for a predetermined number of cycles before and after said measurement period. 
     
     
         13 . The semiconductor device according to  claim 1 , wherein said control unit determines if the module suffers from aged deterioration, based on a difference between a delay time measured at the current time by said delay monitor and a delay value measured previously by said delay monitor.