An analysis of the delay defect detection capability of the ECR test method

An analysis of the energy consumption ratio (ECR) test method, based on simulation study of resistive bridges and resistive opens, is presented. These defect classes comprise a very significant percentage of the defects causing speed failures. We show: (i) bridges causing delay failures and detectable by the difference I_DDQ method is detected by the ECR test method; and (ii) bridges and opens causing delay failures but not detectable by the difference I_DDQ method are also detected by the ECR test method. This highlights a very significant advantage of the ECR test method over I_DDQ test methods. The underlying reason as to why the ECR test method is good at detecting delay defects is presented. Based on that we develop a new test method called the ECR-VDD test. The usefulness of the new method in detecting delay defects is validated using simulation results