Massive parallel semiconductor manufacturing test process

[0002] The present invention relates to temperature cycling units and integrated circuit testing systems and, more specifically, to a massive parallel semiconductor manufacturing test process.

[0003] Integrated circuit (IC) testing is divided into two main stages: package level burn-in and device testing. The package level burn-in is a 24 hour, 125 degree Celsius (C) process which performs device exercising. The package level burn-in is often referred to as a “package level test-in-burn-in” (PLTIBI) and utilizes a burn-in oven and an integrated burn-in environment (IBE) system that can exercise a relatively large number of about 1,248 devices simultaneously. A thousand may also be considered a large number. Since the package level hardware does not contain any external analog-to-digital converters, digital-to-analog converters, etc., the package level burn-in stage cannot perform functional testing on the device.

[0004] The device test stage is utilized to test the functional components of the device. The device test stage includes three steps that test the device at 25 degrees C (Celsius), 140 degrees C, and minus or negative 40 degrees C. The device test stage can only test a relatively small number of devices or ICs at a time. This may be as small as one per machine, but 32 can also be considered a small number. For example, testing the flash in a microprocessor device is a very lengthy process. Since there are many flash tests in the test stage, the time period per device is lengthy and increases test time dramatically. In efforts to overcome the delay, the hot testing of flash has been moved to the package level burn-in stage of the IC testing. However, cold testing is still performed at the test stage of the package level testing and contributes to undesirable delays in the IC testing.

[0005] In the first stage of the IC testing, during the burn-in, portions of an integrated circuit such as flash memory are only exercised, i.e., data is written into the memory, and testing does not occur at the burn-in stage of the IC testing. It would be a significant advantage if flash memory could be tested in parallel at the burn-in stage of the IC testing instead of being tested at the test stage. In this manner, time can be saved in the testing of each of the integrated circuits that are to be tested.

[0006] Upon viewing the present disclosure, those skilled in the art will understand that many other disadvantages exist in the prior art.

[0007] FIG. 1 illustrates an exemplary test system for chamber cycling wherein integrated circuits (ICs) are burned in and partially tested.

[0008] FIG. 2 illustrates an exemplary IC tester system for ICs that are tested with the test system for chamber cycling of FIG. 1.

[0009] FIG. 1 illustrates an exemplary test system for chamber cycling 100 wherein ICs are burned in and partially tested. The test system for chamber cycling 100 includes a temperature cycling chamber (or unit) 102 which is partially controlled through a processor (typically a personal computer) 104. The processor 104 controls driver circuitry 105 to download information onto multiple ICs 107 to at least assist in performing a memory test protocol which includes but is not limited to logical and physical checkerboard patterns, program and erase margin reads, and block erase effect. The ICs 107 contain an electrically programmable memory portion referred to herein as flash memory. ICs 107, in a preferred embodiment, are microcomputers which further comprise a processing unit. Within the temperature cycling chamber 102 are a number of burn-in boards, hereinafter referred to as BIB 106. The BIB 106 includes the ICs 107. The BIB 106 could also be a wafer. As previously stated, the BIB 106 is located within the temperature cycling chamber 102. Dry nitrogen (N₂) 108 is attached to the temperature cycling chamber 102 and is used for purging the temperature cycling chamber 102 after a BIB or wafer 106 is placed inside the temperature cycling chamber 102. The dry nitrogen 108 purges the temperature cycling chamber 102 by removing the moisture that may be located therein.

[0010] The temperature cycling chamber 102, under control of the processor 104, passes the BIB 106 through three different temperatures. In one example, the first temperature is room temperature, which is approximately 25 degrees C. The next temperature is referred to as a hot temperature, which may be one hundred degrees Celsius (C.), but in a preferred embodiment is 125 degrees C. The third temperature is characterized as cold and is preferably negative 40 degrees C. The cold temperature is reached through the use of liquid nitrogen (LN₂) 110. Zero degrees Celsius may be considered a low temperature and provide an effective test, but minus 40 degrees Celsius provides a better test. The three temperatures or settings of the temperature cycling chamber 102 provide the ability to test all integrated circuits on the BIB 106 simultaneously.

[0011] FIG. 2 illustrates an exemplary integrated circuit (IC) testing system 200 for lCs that are tested with the test system for chamber cycling 100. The IC testing system 200 is illustrated as testing a single IC 107. The IC 107 is illustrated in numerous stages of the IC tester system 200 where additional memory test protocols and a processor test protocol are performed on the IC 107. An IC tester 204 performs specific functional testing of the IC 107 at room temperature. The IC 107 then passes to an IC tester 206 where the IC 107 is tested at hot temperatures. Finally, the IC 107 is passed to an IC tester 208 where functional testing is performed at cold temperatures. It should be noted that only one of the IC testers 204, 206, and 208 would be necessary where all ICs of the BIB 106 are passed through such single IC tester at one temperature and then passed through again at another temperature.

[0012] With the test system for chamber cycling 100 and the IC testing system 200, greater testing with an increased test coverage is performed in the test system for chamber cycling 100 which allows for expedited testing of each IC on the BIB 106 when it is passed through the IC tester system 200. In this manner, IC testing can be performed in parallel with a reduction in the time that was previously required to test IC chips. In other words, the IC 107 flash testing is done in batch mode instead of sequential mode. There is batch testing for the memory testing at three temperatures in cycling chamber 102 and then also tested, but at a much reduced quantity of tests, at the individual testers. So the testing and temperature cycling is in parallel.

[0013] The time that utilizes the more sophisticated testing equipment, done in testers such as testers 204, 206, and 208, which can only test a relatively small number of integrated circuits at a time, is done on a much smaller scale because most of the testing is done previously in temperature cycling chamber 102. The tests, both routine and sophisticated, must be run at cold temperature but most of the testing is accomplished with the whole batch of integrated circuits, then tested cold in relatively small numbers, for example, one at a time, in the more sophisticated equipment. The one at a time aspect is thus substantially reduced in time because most of the cold testing is done in a temperature cycling chamber. This results in more efficiency so that testers such as testers 204, 206, and 208, have a higher percentage of their time utilized for the sophisticated tests that they are uniquely qualified to run. Testers 204, 206, and 208 run tests not easily available to be run in batch form in temperature cycling chamber 102. Thus, testers 204, 206, and 208 must be utilized but the efficiency of testing is increased by getting much of the cold testing done prior to using the testers 204, 206, and 208. Testers 204, 206, and 208 are much more expensive than cycling chamber 102 and its accompanying test hardware. Adding many more testers such as testers 204, 206, 208, is potentially a way to reduce test time, but it is a very expensive alternative.

[0014] In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention.

[0015] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.