High voltage/high power wafer testing is done!

High voltage/high power wafer testing is done!

ERS Electronic, headquartered in Munich, Germany, has been focusing on providing temperature testing solutions for more than 50 years. The company has won a good reputation in the industry, especially the chuck system that uses air as the coolant and the temperature changes quickly and accurately. -65°C to 550°C – Analytical, parametric and manufacturing tests are performed over a wide temperature range. At present, AC3, AirCool? PRIME, AirCool? series chucks developed by ERS are used in various large-scale wafer probe test benches in the semiconductor industry.

The high Voltage/current market is one of the fastest growing areas in semiconductor applications today. Driven by the development of electrification and renewable energy, a new generation of power electronic devices is also driving the development of MOSFETs and IGBTs, which is also driving the increasing popularity of other new substrates such as silicon carbide (SiC) and gallium nitride (GaN). .

Gallium Nitride GaN, one of the High Electron Mobility Transistors (HEMTs). Compared with other silicon-based MOSFET devices, it offers significant advantages in large band gaps, extremely short switching times, higher power density and breakdown voltage, and better thermal conductivity. Today, it is widely used in power electronics, such as mobile phone fast chargers, military radar equipment, high-speed rail transit, and 5G networks.

Like GaN, SiC also has high voltage and high temperature characteristics, but due to its varistor characteristics, it performs better than GaN at 600V or higher. As the first successfully commercialized wide-bandgap semiconductor SiC, since it was applied to Tesla cars in 2018, hybrid and electric vehicles and charging stations have become the main driving force for the rapid growth of the SiC power semiconductor market.

As SiC/GaN device technology matures and its cost continues to decrease, SiC/GaN devices are expected to accelerate penetration. According to Yole’s forecast, the market size of SiC and GaN power electronic devices will grow to US$1.4 billion and US$370 million, respectively, in 2023, with a market penetration rate of 3.75% and 1%, respectively. Under the strong demand for 5G macro base station construction and national defense construction, the cost of superimposed GaN radio frequency devices is declining, and the demand is expected to increase rapidly. According to Yole data, the demand for GaN radio frequency devices will reach 194.3 million in 2023, 19-23 The annual CAGR reached 85.8%.

Challenges to the wafer probe industry

Under the background of rapid development of science and technology, the world of power electronics has always been regarded as a relatively conservative field. The emergence of SiC and GaN not only opens a new chapter in the power market, but also brings new challenges to the wafer testing industry. How to maintain the stability and accuracy of the temperature to ensure the yield while meeting the needs of high-power testing is a problem that every design engineer needs to consider.

One of the most important equipment in the semiconductor testing process is the probe station. During the testing process, the wafer is transported to the temperature chuck, so that the dies on the wafer are sequentially contacted with the probe and tested one by one. After testing, the probe station records the chips whose parameters do not meet the requirements, and rejects them before entering the subsequent process flow. In this process, the temperature chuck, which is in close contact with the wafer, plays a decisive role in the test environment.

Compared with the common test environment, in addition to ensuring a wide test temperature range, uniformity and stability of the chuck temperature, etc., the special test environment of high voltage/current also adds more new challenges to the design of the chuck. For example, in a high current test environment, a large contact resistance will accelerate the temperature rise of the wafer. If the heat cannot be dissipated in time, the wafer will be in danger of being damaged. Therefore, when designing a temperature chuck, it is necessary to first Consider how to minimize contact resistance to ensure accurate measurement of RDS(on). Secondly, it is also necessary to ensure low leakage in a high-voltage environment to avoid breakdown. In addition, the chuck also needs to be flexible to deal with some special types of wafers, such as thin wafers, Taiko, etc.

ERS Solutions – High Voltage/Current Temperature Chuck

ERS electronic, which has accumulated more than 15 years of experience in high-voltage testing and ultra-low-noise wafer probe testing, has designed a high-voltage/current testing environment that can guarantee ultra-low leakage, A chuck that avoids breakdown and also has a wide temperature test range (-55°C to +300°C). Its advent has solved many problems in the field of wafer testing under the background of high voltage/current.

Guaranteed ultra-low leakage at high voltages

Through repeated experiments on hundreds of insulating materials under different temperature environments, and considering factors such as production costs, ERS electronic engineers have selected the most suitable insulating material to minimize the contact resistance (Rc) , to ensure ultra-low leakage current in high voltage environment. At present, the chuck supports a maximum current of 600 amps and voltages ranging from 1.5 kV to 10 kV. The specific leakage test parameters are as follows:

High voltage/high power wafer testing is done!

*Table 1: ERS electronic high voltage/current chuck leakage test parameters

Among them, 3 kV Triaxial and 3 kV ULN can reach a voltage of 3 kV through a triaxial connection at a test temperature of up to 300 degrees Celsius. For the measurement of leakage current in the high voltage test, the commonly used test tools are Keysight and Keithley’s series of leakage current detection instruments.

  High voltage/high power wafer testing is done!

*Figure 2-4: Keysight, Keithley’s series of leakage current detection instruments

10kV Coaxial (compatible with 3 kV ULN): When the test voltage is 10 kV, the coaxial connection method can block the voltage up to 10 kV. In addition, the top of the chuck is equipped with an additional direct connect cable to support high voltage/current biasing for wafer testing, and the rest is protected by a grounding setting.

Minimize contact resistance for accurate RDS(on) measurement

Minimize contact resistance, that is, minimize the contact resistance between wafer and chuck. In a broad sense, contact resistance refers to the resistance between conductors, and the real contact resistance is composed of concentrated resistance, film resistance and conductor resistance. There are many factors that affect contact resistance, such as the material of the contact, the force generated by the contact surface and perpendicular to the contact surface, the state of the contact surface, and the magnitude of the applied voltage/current.

Taking the above factors into consideration, combined with years of experience in probe station sealing and integration, the chuck engineers of ERS electronic strictly control the internal and external details of the chuck when developing high-voltage/current chucks, from electrical performance to appearance and structural design. In the production process, the advanced coating technology of ERS electronic is used to ensure the excellent hardness, roughness and flatness of the chuck surface, while reducing the contact resistance, it ensures the consistency of the contact resistance of the entire disk surface, and finally Accurate measurement of RDS(on).

Advanced coating process: guarantees the durability of the chuck

  High voltage/high power wafer testing is done!

*Figure 5: High Voltage/Current Chuck from ERS electronic

With the advanced coating process, ERS electronic’s high voltage/current chuck surface will not be peeled, deformed, oxidized and blackened after repeated use.

Unique Replaceable Chuck Top Plate Service:

Ideal Thin Wafer/Taiko Wafer Solution

  High voltage/high power wafer testing is done!

*Figure 6: Taiko Wafer

With the continuous expansion of chip application fields, chip designs tend to be diversified and customized. Based on different test types and wafer types, the corresponding test solutions are also very different. In the process of long-term contact with customers, ERS electronic found that some testing needs can be met by only replacing the top plate of the chuck. For example, if Taiko wafers need to be tested, it is not necessary to repurchase the chuck, and only replace the suitable Taiko wafers. The test chuck top plate can meet the user’s test needs while greatly reducing the cost. The on-site replacement of the chuck top plate service provided by ERS electronic is designed to cope with the continuous upgrading and changes of today’s testing needs without affecting the production efficiency of enterprises. This service has been widely praised by the industry once it was launched, and it has become a unique solution in the current wafer packaging and testing industry.

Seven reasons to choose ERS high voltage/current chuck

With many years of “customer-centric” business philosophy and strict control of product quality, in addition to a variety of optional test voltage/current and triaxial/coaxial connection methods, ERS electronic’s high voltage/current What makes the chuck stand out from many competitors is the high-voltage and high-temperature performance, which aims to ensure high voltage, ultra-low leakage, and anti-breakdown, while still meeting the customer’s test requirements for high temperature (up to 300°C). It has become one of the biggest technical highlights of ERS electronic high voltage/current chuck.

In addition, ERS electronic’s unique probe stage stage customization service makes it possible to process thin wafers, Taiko wafers and other special-shaped wafers. Customers can not only choose the type of chuck according to their needs, but also choose the service of “replacement of the top of the chuck only” to cope with the constantly escalating semiconductor market of testing needs.

As the third-party technical cooperation partner of ERS Greater China – Shanghai Jingyi Electronic Technology, its CEO Mr. Peng believes, “The high-voltage chuck launched by ERS electronic just makes up for the deficiency in the field of high-voltage/current wafer testing. Combined with high-pressure testing, first-class gold-plated surfaces, and replaceable chuck tops, it provides customers with more flexibility, while also allowing us to see endless possibilities for future technology development in the wafer test industry.”


*Figure 7: Seven reasons to choose ERS High Voltage/Current Chuck

This high voltage/current chuck belongs to the customized chuck service launched by ERS. This series of products also includes a strong vacuum chuck for wafer warpage, a high temperature uniformity chuck suitable for sensors such as temperature and humidity, and a magnetic-free chuck. chucks, and ultra-low noise chucks, etc.

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