Test and repair of interconnects between chips
Embodiments herein relate to a test, repair, and diagnostic solution for chip-to-chip interconnects. In one aspect, on a first chip, a first finite state machine (FSM) is coupled to a set of transmit lanes. To test each transmit lane, one at a time, the first FSM is to apply a first periodic signal to a transmit lane under test and concurrently apply a second periodic signal to other transmit lanes of the set of transmit lanes, where a phase of the first periodic signal is opposite to a phase of the second periodic signal. A comparator compares a detected signal on the lane under test to an expected response. The comparator can be on the first chip, when the first chip is tested alone, or on a second chip, where the two chips are tested together.
1 . An apparatus, comprising:
a set of transmit lanes on a first chip;
a first finite state machine on the first chip, wherein the first finite state machine is coupled to the set of transmit lanes and is to test each transmit lane of the set of transmit lanes, one transmit lane at a time, wherein in the test of each transmit lane of the set of transmit lanes, the first finite state machine is to apply a first periodic signal to the transmit lane under test and concurrently apply a second periodic signal to other transmit lanes of the set of transmit lanes, and a phase of the first periodic signal is opposite to a phase of the second periodic signal;
a set of receive lanes on the first chip; and
a second finite state machine on the first chip, wherein the second finite state machine is coupled to the set of receive lanes and is to test each receive lane of the set of receive lanes, one receive lane at a time, wherein in the test of each receive lane of the set of receive lanes, the second finite state machine is to apply a third periodic signal to the receive lane under test and concurrently apply a fourth periodic signal to other receive lanes of the set of receive lanes, where a phase of the third periodic signal is opposite to a phase of the fourth periodic signal, and to compare a signal detected on the receive lane under test to an expected response.
2 . The apparatus of claim 1 , wherein:
the test of each transmit lane of the set of transmit lanes is part of a sort test of the first chip; and
the first finite state machine comprises a first comparator to identify one or more defective transmit lanes in the set of transmit lanes, wherein to identify the one or more defective transmit lanes, the first comparator is to compare a signal detected on the transmit lane under test to an expected response, during the test of each transmit lane.
3 . The apparatus of claim 2 , further comprising a set of branch lanes to couple the transmit lanes to the first comparator.
4 . The apparatus of claim 2 , wherein the first finite state machine is to determine a repair signature based on the one or more defective transmit lanes, and the repair signature identifies one or more replacement transmit lanes of the set of transmit lanes for the one or more defective transmit lanes.
5 . The apparatus of claim 1 , wherein each transmit lane of the set of transmit lanes is coupled to a respective micro bump of the first chip and each respective micro bump of the first chip is to attach to a respective micro bump of a second chip.
6 . The apparatus of claim 1 , wherein:
the second finite state machine is to identify one or more defective receive lanes in the set of receive lanes and to determine a repair signature based on the one or more defective receive lanes; and
the repair signature identifies one or more replacement receive lanes of the set of receive lanes for the one or more defective receive lanes.
7 . The apparatus of claim 1 , wherein:
each receive lane of the set of receive lanes is coupled to a respective micro bump of the first chip;
each receive lane of the set of receive lanes comprises a respective active-low inverting tristate buffer in series with an inverting buffer; and
in the test of each receive lane of the set of receive lanes, the second finite state machine is to set an enable control line of the respective active-low inverting tristate buffer to a high level to electrically disconnect the receive lane under test from the respective micro bump.
8 . The apparatus of claim 1 , wherein:
each receive lane of the set of receive lanes is coupled to a respective micro bump of the first chip; and
in the test of each receive lane of the set of receive lanes, the second finite state machine is to compare a signal detected on the receive lane under test to an expected response, and the signal detected is received on the receive lane under test from a second chip via one of the respective micro bumps if there is no fault affecting the receive lane under test.
9 . The apparatus of claim 8 , wherein:
each receive lane of the set of receive lanes comprises a respective active-low inverting tristate buffer in series with an inverting buffer; and
in the test of each receive lane of the set of receive lanes, the second finite state machine is to set an enable control line of the respective active-low inverting tristate buffer to a low level to electrically connect the receive lane under test to the respective micro bump.
10 . The apparatus of claim 1 , further comprising:
first and second clock lanes to carry a clock signal;
a clock monitor to determine whether the clock signal on the first clock lane is defective; and
a multiplexer, responsive to the clock monitor, to select the clock signal on the first clock lane if the clock signal on the first clock lane is not defective, and the clock signal on the second clock lane if the clock signal on the first clock lane is defective.
11 . An apparatus, comprising:
a set of receive lanes on a first chip;
a set of interconnects on the first chip, wherein each receive lane of the set of receive lanes is connected to a respective interconnect of the set of interconnects, and the set of interconnects of the first chip are to connect to a second chip;
a signal generator on the first chip;
for each receive lane of the set of receive lanes, a respective switch on the first chip;
a comparator on the first chip, wherein in a test of each receive lane of the set of receive lanes which does not involve the second chip, the respective switches are turned off, and to test each receive lane of the set of receive lanes, one receive lane at a time, the signal generator is to apply a first periodic signal to the receive lane under test and concurrently apply a second periodic signal to other receive lanes of the set of receive lanes, and the comparator is to determine whether a time-shifted version of the first periodic signal is detected on the receive lane under test, wherein in a test of each receive lane of the set of receive lanes which involves the second chip, the respective switches are turned on, and to test each receive lane of the set of receive lanes, one receive lane at a time, the comparator is to determine whether a time-shifted version of a third periodic signal is received on the receive lane under test from the second chip via one of the respective interconnects; and
an error analyzer coupled to the comparator, the error analyzer is to provide a repair signature which identifies one or more replacement lanes for one or more defective lanes in response to the test of each lane of the set of lanes which does not involve the second chip and in response to the test of each lane of the set of lanes which does involve the second chip.
12 . The apparatus of claim 11 , wherein a phase of the first periodic signal is opposite to a phase of the second periodic signal.
13 . An apparatus, comprising:
a set of transmit lanes on a first chip;
a set of interconnects on the first chip, wherein each lane of the set of transmit lanes is connected to a respective interconnect of the set of interconnects on the first chip;
a set of receive lanes on a second chip;
a set of interconnects on the second chip, wherein each lane of the set of receive lanes is connected to a respective interconnect of the set of interconnects on the second chip;
a signal generator on the first chip; and
a comparator on the second chip;
wherein the signal generator, to test each transmit lane of the set of transmit lanes, is to apply a first periodic signal to the transmit lane under test and to apply a second period signal to other lanes of the set of transmit lanes, while the comparator is to determine whether a time-shifted version of the first periodic signal is received on a corresponding receive lane of the set of receive lanes.
14 . The apparatus of claim 13 , wherein a phase of the first periodic signal is opposite to a phase of the second periodic signal.
15 . The apparatus of claim 13 , wherein:
the set of interconnects on the first chip comprise micro bumps;
the set of interconnects on the second chip comprise micro bumps;
the second chip is arranged vertically above the first chip; and
each respective micro bump of the second chip is to connect to a respective micro bump of the first chip.
16 . The apparatus of claim 13 , wherein:
the first chip is separated from the second chip by an intermediate chip; and
each respective interconnect of the set of interconnects on the second chip is to connect to a respective interconnect of the set of interconnects on the first chip through a through-silicon via in the intermediate chip.
17 . The apparatus of claim 16 , wherein:
the set of interconnects on the first chip comprise micro bumps which are to connect to the through-silicon vias of the intermediate chip; and
the set of interconnects on the second chip comprise hybrid bonding interconnects which are to connect to the through-silicon vias of the intermediate chip.