Test system for testing integrated chips and an adapter element for a test system

Test system for testing integrated chips and an adapter element for a test system. One embodiment provides a test system for testing integrated chips in a burn-in test operation, the integrated chips to be tested being arranged in groups on a burn-in board, the burn-in board having a first connecting device in order to connect the burn-in board to a tester device, the tester device comprising a test module with a test circuit in order to test chips on the burn-in board in accordance with the burn-in test operation, the test module having a second connecting device in order to connect the burn-in board to the test module via the second connecting device, a plurality of test modules being provided, the second connecting devices of which can be contact-connected to a plurality of third connecting devices of an adapter element, the adapter element having a fourth connecting device for contact-connection of the first connecting device of the burn-in board, the third connecting devices of the adapter element being connected to the fourth connecting device in such a way that, in the contact-connected state, it is possible to test each integrated circuit of a group with one of the test modules.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. §119 to co-pending German patent application number 103 26 317.9-35, filed Jun. 11, 2003. This related patent application is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a test system for testing integrated chips in a burn-in test operation and also to an adapter element for such a test system.

2. Description of the Related Art

In a test system for a burn-in test operation, the integrated chips to be tested are usually arranged on a burn-in board, i.e., on a burn-in board having receptacles for the integrated chips, and are inserted into a tester device of the test system. The tester device has test modules with driving and evaluation electronics, i.e., with test circuits. When the burn-in board is inserted, a test module of the tester device is connected to the integrated chips on the burn-in board. During the burn-in test operation, the function of the integrated chip is tested under extreme operating conditions, such as elevated ambient temperature, high operating voltage or the like, in order to pre-age the chip and thus to reduce the early failure rate.

Due to the increasing packing density of the burn-in receptacles on the burn-in board, the maximum current limiting of the test module and/or the number of available test channels are often reached or exceeded. This problem arises, inter alia, also during a wafer level burn-in test operation during which the integrated circuits on a wafer are intended to be tested, and thereby pre-aged, simultaneously in one burn-in test operation prior to being separated into individual chips. Successively effected burn-in test operations with the integrated circuits situated on a common wafer cannot be carried out, since the burn-in time would be considerably lengthened and the integrated circuits would experience different pre-ageing conditions.

In order not to exceed the maximum current limiting of the test module or the number of available tester channels, either the packing density of the receptacles on the burn-in boards is reduced or the burn-in boards are only partially populated with integrated chips to be tested. As an alternative, either additional current sources or new test modules have been provided, in order to meet the altered conditions. This has the disadvantage that the burn-in boards are utilized non-optimally, or it has been necessary to accept high costs on account of new test modules and/or additional supply sources.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a test system in which the burn-in board can be fully utilized, without the need for converting the tester device to suitable new test modules for controlling the burn-in test operation.

A first aspect of the present invention provides a test system for testing integrated chips in a burn-in test operation. The integrated chips to be tested can be arranged in groups on a burn-in board. The burn-in board has a first connecting device to connect the burn-in board to a tester device. The tester device comprises a test module with a test circuit to test chips on the burn-in board in accordance with the burn-in test operation. The test module has a second connecting device to connect the burn-in board to the test module via the second connecting device. In the tester device, a plurality of test modules are provided, and the second connecting devices which can be contact-connected to a plurality of third connecting devices of an adapter element. The adapter element has a fourth connecting device for contact-connection of the first connecting device of the burn-in board, the third connecting devices of the adapter element being connected to the fourth connecting device in such a way that, in the contact-connected state, each group of integrated circuits may be tested by means of one of the test modules.

One embodiment provides a test system in which a plurality of test circuits of the test modules can be connected to the integrated chips of a tester palette, such that the integrated chips of a tester palette can be tested by a plurality of test modules. Consequently, the number of integrated chips of a tester palette which are tested by a test module may be reduced. Connecting a plurality of test modules to the integrated chips, on the burn-in board assigned to the test modules via the adapter element, makes it possible to assign supply currents that are virtually as high as desired and a virtually arbitrary number of tester channels to the integrated chips to be tested. This furthermore avoids the need to construct new test modules adapted to the required supply currents and the required tester channels in order to test a tester palette that is fully populated with integrated chips in one burn-in test operation.

It may furthermore be provided that the tester device has a heating chamber in which the burn-in boards can be arranged. The test circuit of the test module is isolated from the heating chamber, and the second connecting device of the test modules extends into the heating chamber in order to be connected to the third connecting devices of the adapter element. In this way, the adapter element can be connected to the second connecting devices in a simple manner without the tester device having to be reconfigured in a complicated manner.

The first connecting device of the burn-in board may include one or more pogo pins which ensure a suitable electrical connection between the burn-in board and the adapter element.

The second connecting devices of the test modules may be formed as contact strips and/or as connector strips which may be arranged in one plane with the test modules.

A further aspect of the present invention provides an adapter element for such a test system. The adapter element makes it possible to leave already available tester devices unchanged and, with the aid of the adapter element, to bundle a plurality of test modules of the tester device such that a burn-in board which is inserted into the tester device is connected to the plurality of test modules. Thus, a higher supply current may be supplied to the integrated chips on the burn-in board, and a larger number of tester channels are made available for testing the integrated circuits arranged on the burn-in board.

The adapter element may include a holding element, on which the third connecting devices are arranged in such a way as to be plugged onto the second connecting devices of the plurality of test modules, so that the test modules are arranged essentially perpendicular to the holding element.

A further aspect of the present invention provides a burn-in board for such a test system, which is configured in such a way as to be connected to the adapter element according to embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The FIGURE shows a test system1according to one embodiment of the invention with a tester device2, into which one or a plurality of burn-in boards3can be inserted. The burn-in boards3have chip receptacles4into which integrated chips can be inserted for testing in a burn-in test operation.

The burn-in test operation of integrated chips usually takes place under extreme operating conditions after their completion. Thus, during the burn-in test operation, the integrated chips are usually operated at an elevated ambient temperature, usually more than 100° C., and with an elevated supply voltage in order to reduce the so-called early failure rate of the integrated chips.

To provide the elevated ambient temperature for the integrated chips to be tested, the tester device2is provided with a heating chamber5, in which the burn-in boards3are situated in the inserted state. Outside the heating chamber5, in a test module region6of the tester device2, test modules7with test circuits8are provided and may be constructed generally identically to carry out the same test program in each case for testing the integrated chips. Furthermore, a supply voltage for the burn-in boards3is made available by the test modules7.

To electrically connect the test circuits8of the test modules7to the integrated chips on the burn-in boards3in the heating chamber5, the test modules7each have a connection device9, which can be connected to the respective test circuit8via a contact-connecting device10. At an end facing the heating chamber5, the connection device9of the test module7has a second contact unit11, which can interact with a third contact unit12of an adapter element13in order to realize electrical connections.

The adapter element13further includes a fourth contact unit14for producing electrical connections to a first contact unit15of one of the burn-in boards3. The chip receptacles4or the integrated chips that can be connected thereto, which may be tested in a burn-in test operation, for example, are arranged in groups on the respective burn-in board3and can be electrically contact-connected via the first contact unit15. Via the first contact unit15, the integrated chips are supplied with signals and with a supply voltage to carry out the test during the burn-in operation.

The adapter element13provides connections for a plurality of the test modules7to a burn-in board3, which is able to test all the integrated chips on a burn-in board3in one burn-in test operation. The adapter element13is necessary since a test module7may make available only a limited current and/or a limited number of tester channels for the testing of the integrated chips on the tester palette (or burn-in board). If the number of tester channels is insufficient or if the current driver capability of the test module7is too low to test all the receptacles with integrated chips in the burn-in test operation, then either only a portion of the chip receptacles4of the burn-in board3may be populated with integrated chips or new test modules7adapted to the integrated chips to be tested and to the number thereof on a tester palette3need to be constructed.

The provision of the adapter element13facilitates bundling conventional tester modules7by providing electrical lines in a suitable manner between the third and fourth contact units12,14in order to make available each of the test modules7contact-connected to the adapter element13in each case to a group of integrated chips. By way of example, if three test modules7are connected to a tester palette3via the adapter element13, then the first tester module can be used to drive a first group, the second tester module7a second group and the third tester module7a third group of integrated chips on the tester palette3.

The provision of the adapter element13makes it possible, in this way, to connect a plurality of tester modules7to the respective integrated chips of a tester palette3. In one embodiment, the adapter element13is provided within the heating chamber5, thus enabling simple insertion into the tester device2. The second and third contact units11,12may be formed as elongated plug contacts which run generally in one plane with the test circuit8of the test module7, which results in a space-saving arrangement.

In order for all the tester modules7to be contact-connected simultaneously, the adapter element13may include a holding element16, on which the third contact units12are arranged generally perpendicularly. The test modules7may be contact-connected simultaneously by the adapter element13being placed onto the second contact units11of the corresponding test modules7.

The first contact unit15may include pogo pins15A which can be pushed into plug contacts14A or the like of the fourth contact unit14such that electrical connections are produced.

In another embodiment, instead of the burn-in boards3on which chip receptacles4for integrated chips are arranged, burn-in boards may be provided for contact-connection of integrated circuits on an unsawn wafer. Such a burn-in board may include a first contact unit of structurally identical configuration to that in the preceding example. However, the integrated circuits on the wafer are contact-connected via a so-called contact card which is placed onto the wafer. The contact card is formed as a needle card comprising contact-connecting needles which are placed onto contact areas of the integrated circuits.

The provision of an adapter element13is particularly useful during the burn-in test operation for integrated circuits on a wafer since, on a wafer, there are generally a large number of integrated circuits which have to be tested in a joint burn-in test operation. The number of integrated chips is essentially determined by the area of the wafer and the size of the integrated circuits and generally does not depend on the capacity of a tester device2for testing the integrated chips in a burn-in test operation. Since the burn-in test operation has to proceed simultaneously for all the integrated circuits in order to ensure a defined pre-ageing process for all the integrated circuits of the wafer, a test circuit8of a test module7has to be provided for each of the integrated circuits upon insertion into the heating chamber5. However, a construction of an adapted test module for essentially all the integrated circuits of a wafer in order to supply all the integrated circuits with a supply current is complicated and very costly. Therefore, the adapter element13, according to embodiments of the present invention, provides bundling of a plurality of conventional test modules7, which become available for the testing of the integrated circuits on the wafer.