关键词: 动态随机存储器, 三维堆叠封装, 温度传感器, 封装应力

Abstract: In three-dimensional stacked dynamic random access memories, the readings of on-chip temperature sensors directly affect refresh strategies and power management. To address the inter-die deviation of temperature sensor readings after packaging, an analytical flow is established to correlate package structure, local stress, sensitive devices, and temperature-code shift. By comparing the temperature differences of different samples in post-packaging tests and combining structural verification with various overhang configurations, the influence of package structure on temperature sensor deviations is analyzed. The results show that, after appropriately increasing the overhang of multiple test chips, the temperature gap between the upper and lower dies is reduced from 6~7 ℃ to 2~3 ℃. Further package-stress and device simulations indicate that the N-type metal-oxide-semiconductor current mirror in the complementary-to-absolute-temperature current branch is more sensitive to stress, and its saturation drain current variation can explain the major temperature-code shift. Finally, this study proposes optimization constraints for package co-design and stress-aware layout based on temperature sensors in stacked memories.

Key words: dynamic random access memory, three-dimensional stacked packaging, temperature sensor, package-induced stress