HTOL (High Temperature Operating Life Test) is a testing method that determines product reliability by accelerating the thermal activation failure mechanism. This test is conducted in a simulated high-temperature working environment to evaluate the durability of the device under conditions of overheating and overvoltage.
HTOL testing typically follows the following testing standards:
JESD22-A108B：Temperature, Bias, and Operating Life， Detailed regulations have been established for the conditions and procedures of high-temperature operation life testing.
MIL-STD-883 Method 1005.8: Specific requirements for high-temperature life testing in US military standards.
EIAJ-ED4701-D323： The standards of the Electronics Industry Association also include relevant content on high-temperature life testing.
High temperature life test conditions:
Temperature: Usually higher than the normal operating temperature of the product, such as 125 ℃ or higher.
Voltage: Generally, it is the maximum operating voltage (VCC max) or slightly higher than this value.
Time: The aging time is usually 1000 hours, with functional backtesting conducted at 168 hours and 500 hours in between.
HTOL testing mainly focuses on the failure modes of devices in high-temperature environments, including but not limited to:
Electron migration: The migration of electrons in metal conductors at high temperatures leads to failure.
Oxide layer rupture: High temperature accelerates the degradation of the oxide layer, ultimately leading to failure.
Mutual diffusion: The mutual diffusion of different materials at high temperatures causes a decrease in performance.
Instability: Device performance fluctuations and instability caused by high temperatures.
LTOL (Low Temperature Operating Life Test) refers to the low-temperature life test, which mainly aims to evaluate the durability and hot carrier degradation of devices in low-temperature environments. Due to the more pronounced injection effect of hot carriers at low temperatures, LTOL testing is particularly important for certain specific types of devices, such as memory devices or sub micron sized devices.
LTOL testing typically follows the following testing standards:
JESD22-A108： Although sharing the same standard with HTOL, the testing conditions are different, especially in terms of temperature.
Other standards: Based on actual user needs and testing design, reference may also be made to other standards or customized testing conditions.
Low temperature life test conditions:
Temperature: The junction temperature (Tj) usually does not exceed 50 ℃, but the actual testing temperature may be lower, such as in the range of -55 ℃ to 0 ℃.
Voltage: usually the maximum operating voltage (VCC max) or higher.
Time: The aging time is usually 1000 hours.
LTOL testing mainly focuses on the failure modes of devices in low-temperature environments, especially those related to the degradation of hot charge carriers. These modes include but are not limited to:
Hot carrier injection effect: The hot carrier injection effect intensifies at low temperatures, leading to device performance degradation.
Material embrittlement: Low temperatures may cause certain materials to become brittle, increasing the risk of mechanical damage.
Interface failure: Differences in thermal expansion coefficients of different materials at low temperatures may lead to interface failure.
Hot carrier injection: In contrast to HTOL, the hot carrier effect is more pronounced at low temperatures, leading to damage to the oxide layer.
Low temperature brittleness: Low temperatures may cause materials to become brittle, increasing the risk of fracture at packaging or connection points.
Charge capture: Under low temperature conditions, the capture and release behavior of charges in semiconductors changes, affecting the stability of the device.
Dielectric breakdown: Low temperatures may accelerate the aging of certain types of dielectric materials, leading to breakdown.
Both HTOL and LTOL testing are aimed at accelerating the aging process of integrated circuits under extreme temperature conditions, in order to quickly identify potential failure modes. These tests help manufacturers conduct necessary design optimization and quality control before launching their products into the market. Different standards provide specific guidance for conducting these tests, including temperature settings, test duration, voltage and current conditions, etc.

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