Semiconductor handler for rapid testing

Details Semiconductor handler for rapid testing Semiconductor handler for rapid testing

2000-06-01

2004-04-06

Paik, Sang (Department: 3742)

Electric heating

Heating devices

Combined with container, enclosure, or support for material...

C118S724000

Reexamination Certificate

active

06717115

ABSTRACT:

BACKGROUND
This invention relates generally to the manufacture of semiconductor devices and more specifically to a handling device that thermally conditions devices and presents them to a test system.
In the manufacture of integrated circuit chips, the chips are generally tested at least once. The test results are used in various ways. They can be used to separate good chips from faulty chips. They can also be used to grade parts. For example, chips are usually rated by the maximum speed at which they can operate or by the amount of the data they can store, with the chips having a higher speed or larger memories being sold at higher prices. Often, variations in the chip manufacturing process result in some chips operating at a higher speed or having more usable memory. The test results allow the parts that have greater capabilities to be graded for sale at a higher price. In some cases, defects on chips can be repaired using laser repair stations or similar equipment. Another way that test results might be used in the manufacture of chips is to guide the repair of chips.
Usually, automatic test equipment is used to run the tests. A handling device is used to present the chips to the automatic test system in an automated fashion. A handling device that handles packaged parts is usually referred to as a “handler.” To fully test chips, tests are often run at multiple temperatures over the rated operating range of the chip. For example, many chips are tested over a range that spans from −55 deg C. to +155 deg C. The handler, in addition to moving the chips to and from a test station, often heats or cools the parts to the desired test temperature.
The main drawback of present test handler thermal systems, which are mainly convection based, are the long slew times (20 to 60 minutes) and long soak times (>2 minutes). “Slew time” refers to the length of time it takes for the handler to reach the desired operating temperature. “Soak time” refers to the amount of time a chip must be in the handler until it reaches the desired temperature for a test.
A short slew time is important in being able to quickly recover from jams or machine failures, especially during cold testing when the machine must often be reheated to remove frost and condensation. In addition, the slew time and the soak time affect the package changeover time—the time it takes to reconfigure a machine to test a new type of device. The slew time plays a role in that when a package changeover is needed the handler must be brought back to an ambient-level temperature, the hardware and software configuration changes made, and then brought to the desired test temperature. Once the machine reaches temperature, the soak time plays a role in that it defines the time it takes for the first device to reach the test site, if the system is not mechanically limited in speed. Finally, in the case where a new lot of devices is loaded, the soak time plays the dominating role and defines the time it takes for the first device to be tested, if the system is not mechanically limited in speed. The slew time and soak time become even more dominant in describing the overall effectiveness or efficiency of a machine, because the frequency of new lots and changeovers has constantly been increasing.
In addition many convection based thermal systems end up rather large and have trouble with tight temperature control of devices, particularly in the case of high parallel test. Conduction-based thermal systems have in the past been considered for use in test applications. However, they do not provide a means to achieve a high thermal slew rate design that meets the test temperature range and tolerance requirements (−55 deg C. to 155 deg C. and ~±2 deg C.). The greatest use of conduction based thermal systems in test today is in probe applications (wafer test), where a temperature-controlled chuck (thermal chuck) provides a means to support, transport, align, temperature control and test the ICs on a wafer.
Thermal chucks are available commercially such as from Thermonics Incorporated of Santa Clara Calif. and Temptronic Corporation of Newton Mass. These wafer chucks have limited performance capability over the complete hot-and-cold test temperature range. Specifically, their slew-rate performance is limited because they use a closed-loop mechanical refrigeration system needed for clean-room operation. Their slew-rate performance is also limited because the thermal mass of the thermal chuck is too large.
Closed loop refrigeration systems generally can not provide a fast enough and great enough cooling and heating source to achieve the desired short ramp rates (~5 minutes) over the complete −55 deg C. to 155 deg C. temperature range. In addition, these thermal chucks are all single-zone thermal systems, where heating and cooling of the chuck is regulated by feedback from one temperature sensor. In probe applications however, slew rates are not as important because of the much longer time it takes to test a wafer than it takes to test a group of packaged devices; a wafer can hold hundreds of ICs. In addition, all ICs are processed on a very limited number of different wafers, differing only in diameter e.g. 200 mm, 300 mm. Therefore, the number of different chuck designs is very limited, and the only changeover typically is that necessary to change the test interface, probe interface components, or software/test program. On a final note, the soak time is generally much faster for a wafer than it is for a packaged device because of the extremely high surface finish and flatness of a wafer and high thermal conductivity of silicon compared with the properties of traditional packaged devices (e.g. ceramic and “plastic” packaged parts). Given this and the low influence of the soak time, probers are not built with thermal conditioning buffer capacity.
Conduction-based thermal systems in package test (handler applications) have been used, but these were mainly for active temperature control of high-power devices under test, and therefore require feedback of the device or the device die (junction) temperature as in the prior patents by Jones (U.S. Pat. No. 5,420,521) and by Tustaniwskyj (U.S. Pat. No. 5,821,505). This functionality of active temperature control based on device power dissipation is not required for the large majority of ICs which are relatively low-power devices (less than about 10 W), therefore this adds unnecessary cost and control complexity (control-feedback system required and intended for each device). Furthermore, typically only the high-end microprocessor devices have built-in temperature sensors, which could be used for temperature control purposes during test (U.S. Pat. No. 5,821,505). An external control element such as in Jones (U.S. Pat. No. 5,420,521), requires that the sensor align with and contact each device under test. Given the vast nature of device types, achieving alignment of the temperature sensors with each device type/package type is difficult, costly, and time consuming. Finally, these systems as described in Jones (U.S. Pat. No. 5,420,521), Tustaniwskyj (U.S. Pat. No. 5,821,505), and Tustaniwskyj (U.S. Pat. No. 5,844,208) require a clamping action to sandwich the device between the conduction system and the electrical test socket to achieve the necessary pressure between the device and the conduction system. In automation equipment, it is most often necessary and preferred to handle (pick up) and hold devices down using vacuum. The patents by Tustaniwskyj (U.S. Pat. No. 5,821,505) and Tustaniwskyj (U.S. Pat. No. 5,844,208) clearly state that additional mass changes the intention, performance, and nature of their invention.
The conduction-based design by Micro Component Technology Inc. of St. Paul, Minn. in U.S. Pat. No. 5,966,940 requires the use of thermoelectric elements. A “thermo-electric element” refers to a device that will generate heat when a electricity is applied in one direction and will cool when electricity is applied in the opposite direction. These provide a means for som

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