Molded plastic carrier for testing semiconductor dice

Details Molded plastic carrier for testing semiconductor dice Molded plastic carrier for testing semiconductor dice

1996-03-13

2001-11-20

Karlsen, Ernest (Department: 2858)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S754090, C324S765010

Reexamination Certificate

active

06320397

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to semiconductor manufacture and more particularly to a carrier suitable for holding and establishing electrical communication with an unpackaged semiconductor die. The carrier is useful in the manufacture and testing of known good semiconductor die (KGD).
BACKGROUND OF THE INVENTION
One of the fastest growing segments of the semiconductor industry is the manufacture of multi-chip modules (MCM). Multi-chip modules are being increasingly used in computers to form PC chip sets and in telecommunication items such as modems and cellular telephones. In addition, consumer electronic products such as watches and calculators typically include multi-chip modules.
With a multi-chip module, non-encapsulated or unpackaged dice (i.e., chips) are secured to a substrate (e.g., printed circuit board) using an adhesive. Electrical connections are then made directly to the bond pads on each die and to electrical leads on the substrate. In general, unpackaged dice cost less to manufacture than the equivalent packaged products. This is because the procedures for packaging semiconductor dice are complex and costly. Substantial cost savings are realized by eliminating packaging procedures.
However, because there is no package, procedures for testing the unpackaged dice are more difficult than test procedures for packaged dice. With unpackaged dice semiconductor manufacturers are required to supply dice that have been tested and certified as known good die (KGD). Known-good-die (KGD) is a collective term that connotes unpackaged die having the same quality and reliability as the equivalent packaged product. This has led to a need in the art for manufacturing processes suitable for testing bare or unpackaged semiconductor die.
For test and burn-in of an unpackaged dice, a carrier replaces a conventional single chip package in the manufacturing process. The carrier typically includes an interconnect that allows a temporary electrical connection to be made between external test circuitry and the die. In addition, such a carrier must allow the necessary test procedures to be performed without damaging the die. The bond pads on a die are particularly susceptible to physical damage during the test procedure.
In response to the need for known good die (KGD), semiconductor manufacturers have developed carriers for testing unpackaged die. As an example, carriers for testing unpackaged die are disclosed in U.S. Pat. No. 4,899,107 to Corbett et al. and U.S. Pat. No. 5,302,891 to Wood et al., which are assigned to Micron Technology, Inc. Other test apparatus for unpackaged die are disclosed in U.S. Pat. No. 5,123,850 to Elder et al., and U.S. Pat. No. 5,073,117 to Malhi et al., which are assigned to Texas Instruments.
One of the key design considerations for a carrier is the method for establishing a temporary electrical connection with the bond pads on the die. With some carriers, the die is placed circuitry side down in the carrier and biased into contact with the interconnect. The interconnect contains the contact structure that physically aligns with and contacts the bond pads of the die. Exemplary contact structures include wires, needles, and bumps. The mechanisms for making electrical contact include piercing the native oxide of the bond pad with a sharp point, breaking or burnishing the native oxide with a bump, or moving across the bond pad with a contact adapted to scrub away the oxide. In general, each of these contact structures is adapted to form a low-resistance ohmic contact with the bondpad. Low-resistance refers to a resistance that is negligible. An ohmic contact is one in which voltage appearing across the contact is proportional to current flowing for both directions of flow.
Other design considerations for a carrier include electrical performance over a wide temperature range, thermal management, power and signal distribution, the cost and reusability of the carrier, and the ability to remove and replace the temporary interconnect. In addition, a carrier should be suitable for use with automated equipment and assembly procedures utilized in high volume semiconductor manufacture.
In view of the foregoing, it is an object of the present invention to provide an improved carrier adapted to test and burn-in an unpackaged die without damage to the die. It is a further object of the invention to provide an improved carrier for testing an unpackaged die, that is reusable, that is easy to assemble and disassemble, that provides efficient electrical coupling to contact locations on a die over a wide temperature range, and that can be used for testing different types of dice using a removable and reusable interconnect. It is yet another object of the present invention to provide an improved carrier that does not include protruding mechanical pins or leads. Other objects, advantages, and capabilities of the present invention will become more apparent as the description proceeds.
SUMMARY OF THE INVENTION
In accordance with the present invention, a carrier for testing a discrete, unpackaged semiconductor die is provided. The carrier is adapted to retain a die under test (DUT) and provide a temporary electrical connection between the die and external test circuitry. This enables burn-in and other test procedures to be performed on the die. In an illustrative embodiment, the carrier includes a multi-layer ceramic base having internal conductive lines and metal plated external contacts. In an alternate embodiment the carrier includes a molded plastic base having plated metallic 3-D conductive lines and external contacts. With either embodiment the carrier is formed without protruding mechanical pins or leads that can be easily damaged.
Both carrier embodiments include a temporary interconnect mountable on the base for establishing a temporary electrical connection to the die under test. In addition, a force distribution mechanism is provided for biasing the die and interconnect together. The force distribution mechanism includes a bridge clamp, a spring and a pressure plate. All of the elements of the carrier are reusable and are designed to permit reusability and easy assembly/disassembly of the carrier and die.
The temporary interconnect for the carrier is formed in a configuration which accommodates a particular die bondpad configuration. This permits different types of interconnects to be interchangeable to allow testing of the different types of semiconductor dice using a universal carrier. The temporary interconnect includes raised contact members for penetrating into contact locations (e.g., bond pads, test pads) on the die. A pattern of conductive traces is formed on the interconnect in electrical communication with the contact members. Each conductive trace includes a contact pad, which in the assembled carrier, are used to establish an electrical path to the external contacts on the carrier using wire bonding or a mechanical connection.
For assembling the carrier with a die, a temporary interconnect having a configuration of contact members corresponding to the bond pads on the die is selected and placed on a mounting surface formed on the carrier base. An electrical path is then established between the contact members on the interconnect and the external contacts on the carrier base by we bonding or other electrical connection (e.g., clips). During the assembly procedure, the die is initially attached to the force distribution mechanism, typically using a vacuum. Next, the die and temporary interconnect are optically aligned using a vision system, and the die is placed into abutting contact with the temporary interconnect with a controlled or predetermined force. This causes the contact members on the interconnect to penetrate into the contact locations on the die and establish an electrical connection. At the same time, the force distribution mechanism is attached to the carrier base to bias the die and interconnect together. The external contacts on the assembled carrier are then attached to test circuitry using a socket or other connection and the

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