Program overview
At present, due to the increasing storage density of Flash Memory storage devices and the continuous updating of chip production process nodes, the process of less than 20 nm is becoming more and more common in the manufacturing of memory devices. The continuous expansion of line width not only brings challenges to manufacturing, but also brings new challenges to X-ray inspection in the assembly process. The experiment proves that the memory chip will lose the data due to the electronic transition under the X-ray irradiation for a long time, which will make the product system fail. X-ray inspection is an indispensable reliability means in the assembly process. In order to avoid chip damage, we propose the following solutions for your reference to help factory engineers reasonably avoid product failure when using X-ray equipment.
一、X-ray absorption capability test of Flash memory
1. 测试流程:
-
-
•KV=100KV, distance from focus to chip =200mm
• Set different target powers and record the X-ray intensity without the chip placed
• Set different target powers and record the X-ray intensity after placing the chip
• Calculate the X-ray intensity difference, which is the X-ray energy absorbed by the chip
2. Test results:
Note: Due to range limitation, RADEYE G-10 (max100mSv/h), the value in red is the calculated value
X-ray absorption capability test of Flash memory
Conclusion:
KV=100KV, FOD=200mm
X-ray (mSv/h) energy absorbed by the chip = 18+ 22 * (Target Power - 0.2W)
3. Define the maximum allowable detection time based on daily detection parameters
Select the usual detection setting condition:
• KV:100KV
• Target power 0.5W
• Sample to focus distance (FOD): 27.5mm
According to Samsung chip specifications: the maximum tolerance of X-ray absorption is 0.5Ra, and 3.75mSv is selected as the safety value according to 70% of the safety valve value to ensure that the maximum inspection time can be calculated after X-ray inspection.
Detection time (s) = 3.75/449.59 * 3600 = 30 Sec
The maximum X-ray irradiation time of the sample is less than 30 sec. The X-ray energy absorbed by the sample is less than 0.375Rad, and the inspection process is safe.
Second, how to prevent the damage of the memory chip during the X-ray inspection
1. Add a collimator
Reduce the XX ray cone Angle from 170 degrees to about 40 degrees.
Purpose: To detect one of the chips, the other chips will not be illuminated (memory chips are usually clustered).
As shown below
2. Use FNC program to detect the chip automatically
Fixed detection parameters using FNC:
KV: 100KV
Target power :0.5W
Distance between focus and sample :27.5mm
The detection is fully automatic and the total exposure time of the chip is controlled by the machine
If you are interested in this article, please immediatelycontact us
