Semiconductor | Key Technologies of Ultrasonic Scanning Equipment for Semiconductor Chips

With the continuous development of the semiconductor industry, the requirements for semiconductor device manufacturing processes are becoming increasingly stringent. Since defects such as solder layer voids, cracks, and delamination can lead to the failure of semiconductor devices during long-term operation, the market urgently needs a high-resolution, high-sensitivity, and highly sensitive non-destructive testing tool for bonded surfaces. Therefore, ultrasonic scanning technology has been introduced into semiconductor device manufacturing lines. At the 13th Semiconductor Discrete Device Annual Conference and Suzhou Third-Generation Semiconductor Industry Integration and Innovation Development Summit Forum, the General Manager of the Semiconductor Business Unit of Suzhou Guanglinda Electronics Technology Co., Ltd. delivered a speech entitled...Key Technologies and Localization of Ultrasonic Scanning Equipment for Semiconductor ChipsThe following is the core content of the speech.

01 Ultrasonic Testing Principle

Ultrasound is a sound wave with a frequency exceeding 20 kHz, which is outside the frequency range of human hearing (the frequency range of sound that the human ear can hear is 16 Hz-20 kHz). When the homogeneity inside a material changes, its acoustic impedance changes, and the amplitude and phase of the echo signal change. By displaying the waveform data (such as peak value, time, etc.) with different colors or grayscale values, the internal structure of the sample under test can be displayed in real time.

Comparison of X-ray scanning and ultrasound scanning

02 Key Technologies

Scanning mode

     Reflection scanning mode:

A single probe can be used to both transmit and receive ultrasonic waves.

Depending on the scanning method, they are called A-Scan, B-Scan, and C-Scan. In addition, there are D-Scan, X-Scan, G-Scan, Z-Scan, and other scanning methods.

For specific dimensions, the image is clear.

     Transmission scanning mode:

A detection method similar to X-ray detection, using transmitted ultrasound as a signal.

Ultrasonic signals can penetrate the entire sample being tested, and defects at all interfaces can be detected in a single scan.

The image is not as clear as the reflection.

Autofocus scanning technology

Traditional surface tracking techniques often fail to detect severely warped samples (such as thinned wafer-bonded samples) due to defocusing. However, by employing autofocus scanning technology, the probe's Z-axis can be adjusted up and down in real-time during scanning to follow the surface undulations of the sample, ensuring continuous focus on a specific interface within the sample. This allows for tracking of even 2-5mm warped sample surfaces.

Frequency division scanning technology

Frequency division scanning technology can divide a single-frequency probe into multiple frequency bands for simultaneous detection. Using Fourier transform, the echo signal is decomposed into different frequency bands. Through frequency conversion, an existing probe can be set to any frequency band for scanning, selecting the frequency band with the clearest image. This technology effectively utilizes existing probes, reduces the cumbersome process of changing probes, and increases scanning speed.

Interpolation scanning technique

Taking advantage of the high-speed data acquisition capability of ultrasound scanning, interlaced scanning followed by classical image interpolation can yield ultrasound images of comparable clarity in half the time. This is particularly useful when high resolution is not required.Significantly improve scanning efficiency。

03 Technology Application

After years of dedicated work, Guanglinda has successfully developed a mature product based on ultrasonic scanning technology—the Ultrasonic Scanning Microscope (GRD-CS3). This product primarily utilizes high-frequency ultrasound to inspect various semiconductor devices and materials, exhibiting high sensitivity to bonded surfaces and capable of detecting…Defects such as pores, cracks, inclusions, and delamination inside the sampleIt displays the results graphically. The scanning process does not damage the sample or affect its performance. Currently, this product is widely used in semiconductor device and packaging testing, materials testing, and IGBT power module product testing.