Expanding Knowledge: The Importance of ESD Testing for Chips

As is well known, semiconductor testing runs through the entire semiconductor industry chain, requiring corresponding testing from chip design, wafer manufacturing, and ultimately chip packaging to ensure product yield. The testing equipment mainly includes three categories: chip testing machines, IC probe stations, and sorting machines. During the process of chip testing using a chip testing machine, ESD testing indicators are a crucial indicator to characterize the reliability of the chip. Today, I would like to share with you the ESD testing in chip testing.

                  What is ESD

ESD stands for Electric Static discharge, which means "electrostatic discharge".

                   The impact of ESD on chips

Chip level ESD, when we use chips in our daily lives, we occasionally use our hands to hold them or use tweezers to hold them, which can result in more or less ESD. In fact, in our normal environment or laboratory environment, there is not such a high level of ESD. Usually, chips can withstand it and will not cause fatal damage to the chips. On the production line, ESD may be relatively high. In areas where yield is important, emphasis will be placed on wearing electrostatic wristbands, gloves, etc.

In a typical working environment, the human body capacitance is about 150pf, and if the induced charge is about 0.6 μ C. So it will lead to an electrostatic potential of 4 KV, at which point the electrostatic energy carried by the human body is 1.2 millijoules. What would happen if a charged human body acts on an integrated circuit? It will generate a strong electric field and then break down some insulators or PN junctions inside the integrated circuit; It will discharge the components inside the integrated circuit, although the time is very short, with a typical value of about 10ns~100ns, but the instantaneous current can reach 1A~10A, which is enough to cause thermal damage to semiconductor devices. Due to the wide range of human activities and the tendency to overlook static electricity, human electrostatic discharge is often one of the main causes of electrostatic damage to semiconductor devices, and it poses the greatest harm to semiconductor devices.

Due to the different causes of ESD and the different ways it discharges integrated circuits, ESD is currently classified into the following four categories:

HBM, this model is established to simulate human hand contact with chips, with an equivalent human resistance of 1.5K and an equivalent capacitance of approximately 100pF. As shown in the following figure:　　

                                                                  HBM equivalent circuit diagram

               HBM current waveform diagram

                  Test value reference table

                                                                         ESD testing machine

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ESD testing is conducted during semiconductor reliability testing and is essential for quality assurance in the development of semiconductor design and the final production process of semiconductor manufacturing. In the global testing machine market, most of the testing machine production products are monopolized by the United States, Japan, Taiwan, and other countries. There are very few domestic testing machine manufacturers, and only companies such as Shenzhen Tech Optoelectronics and Changchuan Technology have production capacity. Among them, in ESD testing, Shenzhen Tech Optoelectronics is also one of the few domestic companies, and the technical level of ESD testing in the chip testing machine field has reached the level of Japanese and Taiwanese enterprises. A dark horse belonging to the rising star, it also represents the highest level of ESD testing in the domestic chip testing machine field.

ESD testing is usually carried out in LED chip testing machines, such as the fully automatic inverted LED chip testing machine from Shenzhen Tech Optoelectronics, which is equipped with the 4KV version of the ESD discharge tester from Tech Optoelectronics.

Tech Optoelectronics Inverted LED Chip Testing Machine

The Tec Optoelectronics fully automatic inverted LED chip testing machine has the following functional characteristics：

• Prober&Tester integrated all-in-one machine design, with industry-leading testing speed and accuracy;
  
• The Japanese made high-precision screw guide rail has strong mechanical rigidity and long service life. At the same time, it is combined with a precision grating ruler to achieve full closed-loop control of motion, with ultra-high positioning accuracy and long-term operational stability;
  
• The whole machine adopts an instrument marble platform and a sunken design, which has excellent running stability;
  
• Optimizing and reducing the size of the organization to improve the utilization rate of the factory building;
  
• The self-developed real-time weighing active electrode edge finder can effectively control the contact force between the probe and the chip electrode during each test, ensuring the consistency of needle marks;
  
• Autonomous inverted light receiving structure with higher optical sensitivity and accuracy, suitable for testing up to 6 "[* Note 1] Mini LED chips, conventional inverted chips, and CSP chips;
  
• Optional integration balls of 1 ", 1.5", and 2 ", equipped with 7 levels of filters to meet the testing requirements of chips with different brightness levels, capable of measuring micro current illumination;
  
• Multi needle design can achieve the requirement of simultaneous measurement of multiple particles, improving the testing capacity of the machine;
  
• Equipped with automatic needle cleaning function;
  
• The machine is equipped with a zoom needle mark camera, which automatically takes needle mark confirmation during production to ensure stable production;