Features Of Silicon Nitride Ceramic Substrates

As we all know, the heat generated by the operation of semiconductor devices is the key factor that causes the failure of semiconductor devices, and the thermal conductivity of the electrical insulating substrate is the key to the heat dissipation of the overall semiconductor device. In addition, due to the complex mechanical environment such as bumps and vibrations, the substrate material with certain mechanical reliability is also required. Silicon nitride ceramic is more balanced in all aspects, and is structural ceramic materials with the best overall performance. Therefore, Si3N4 silicon nitride has strong competitiveness in the field of ceramic substrate manufacturing for power electronic devices.

In the past, the circuit substrate is a combination of separate components or integrated circuits and discrete components to form a flat material that meets the requirements of the overall circuit function. It requires only electrical insulation and conductivity. After entering the era of intelligent information, power electronic devices are also required to be able to convert and control electrical energy, which greatly improves the electrical control and power conversion performance requirements and operating power consumption of the devices. Correspondingly, ordinary substrates can no longer meet the high requirements of reducing the thermal resistance of complex power devices, controlling the operating temperature, and ensuring reliability, a substrate with better performance must be replaced, and a new type of power ceramic substrate has emerged.

Based on the performance requirements of electronic devices for ceramic substrates, the substrate material should have the following properties:

1. Good insulation and resistance to electric breakdown;

2. High thermal conductivity: thermal conductivity directly affects the operating conditions and service life of semiconductors, and the uneven temperature field distribution caused by poor heat dissipation will also greatly increase the noise of electronic devices;

3. The thermal expansion coefficient matches with other materials used in the package;

4. Good high frequency characteristics: low dielectric constant and low dielectric loss;

5. The surface is smooth and the thickness is uniform: it is convenient to print the circuit on the surface of the substrate, and to ensure the uniform thickness of the printed circuit.

At present, the most widely used ceramic substrate materials are mainly Al2O3 Aluminum Oxide and AlN Aluminum Nitride. How does silicon nitride compare to their performance? The following table is the basic performance comparison of the three ceramic substrates. It can be seen that silicon nitride ceramic materials have obvious advantages, especially the high temperature resistance performance of silicon nitride ceramic materials under high temperature conditions, chemical inertness to metals, and ultra-high Mechanical properties such as hardness and fracture toughness.

* The reliability test is the number of times that the material is not damaged under the condition of -40 degrees Celsius to 150 degrees Celsius.

Since silicon nitride is so excellent, why is there still less market application, and where are its development opportunities? In fact, the three materials have their own advantages and disadvantages. For example, although alumina has poor thermal conductivity and cannot keep up with the development trend of high-power semiconductors, its manufacturing process is mature and low-cost, and there is still a large demand in the low-end and mid-range fields. Aluminum nitride has the best thermal conductivity and has a good match with semiconductor materials. It can be used in high-end industries, but the mechanical properties are poor, which affects the life of semiconductor devices and has a higher cost of use. Silicon nitride has the best performance in terms of overall performance, but the entry barrier is high. At present, many domestic research institutes and enterprises in China are studying, but the technology is difficult, the production cost is high, and the market is small, so large-scale applications have not yet appeared. This is the reason why many companies are still waiting to see and have not made up their minds to increase investment. However, the situation is different now, because the world has entered a critical period for the development of the third generation of semiconductors. Silicon nitride ceramic circuit substrates have matured products in the United States and Japan. China has a long way to go in this area. There is a way to go. With the development of technology and the increase in market demand, UNIPRETEC believes there will be more and more results that can be shown.