Method and apparatus for enabling a digital memory tester to read the frequency of a free running oscillator
AssigneeMicron Technology, Inc.
InventorSimon J. Lovett
Life of this patent
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Abstract
An apparatus and method are provided for testing and sorting semiconductor dies based on performance characteristics. A tester is provided that supplies a pulse to an oscillator fabricated in association with a die under test. A counter is provided which counts oscillations of the oscillator to a predetermined value. Once the counter counts to the predetermined value, it provides a signal to the tester. The tester determines the elapsed time between when the oscillator is activated and when the signal is received from the counter and determines the frequency of the oscillator from the elapsed time.
Claims29
A method for indicating operating speed of a semiconductor die, the method comprising:
- providing a signal to an oscillator fabricated in association with a die;
- counting output pulses of said oscillator up to a predetermined value of pulses stored in a counter;
- determining a time period between the time said oscillator is activated until said predetermined value is counted;
- and
- using said time period to determine the frequency of said oscillator.
A method for sorting a semiconductor die according to the performance characteristics of the die, the method comprising:
- providing a signal to activate an oscillator fabricated in association with a die to be tested;
- counting output pulses of said oscillator to a maximum value of pulses countable by a counter;
- determining a time period between the time said oscillator is activated until said predetermined value is counted;
- using said time period to determine the frequency of said oscillator;
- and
- using said determined frequency as at least one criteria for sorting said die.
An apparatus for indicating operating speed of a semiconductor die, the apparatus comprising:
- an oscillator fabricated in association with a die for producing an oscillating signal;
- a signal generator for activating said oscillator;
- a counter for counting oscillations from said oscillator up to a predetermined value stored in said counter;
- a testing apparatus for determining the time period between the time said oscillator is activated and said predetermined value is counted and for determining the frequency of said oscillator from said time period.
A fabricated die comprising:
- an oscillator;
- a counter coupled to said oscillator for counting oscillations of said oscillator to a predetermined value of oscillations;
- a first signal line coupled to said oscillator for receiving an activation signal external of said die which turns said oscillator on;
- and
- a second signal line coupled to said counter for providing a signal external to said die when said counter counts to said predetermined value.
An apparatus for sorting a semiconductor die according to the performance characteristics of the die, the apparatus comprising:
- an oscillator fabricated in association with a die for producing an oscillating signal;
- a signal generator for activating said oscillator,
- a counter for counting oscillations from said oscillator to a predetermined value;
- and
- a tester for sending a signal to activate said oscillator, for determining the time period between activating said oscillator and counting said predetermined value, for determining the frequency of said oscillator based on said time period, and for providing information for sorting said die based on said determined frequency.
An apparatus for marking semiconductor dies according to performance characteristics of the dies, the apparatus comprising:
- an oscillator fabricated in association with a die for producing an oscillating signal;
- a signal generator for activating said oscillator;
- a counter for counting oscillations from said oscillator up to a predetermined value of oscillations;
- and
- a tester for sending a signal to activate said oscillator, for determining the time period between activating said oscillator and counting said predetermined value, for determining the frequency of said oscillator based on said time period, and for marking said die according to said determined frequency.
Dependencies are inferred from the claim text.