This invisible perhaps unimaginable--width is the smallest achievable distance between lines of metal on a chip (the "process dimension"). As Hu says, describing the difficulty of the submicron manufacturing process, "they have to be close, but not too close."
這樣肉眼不能見、甚至無從擬想的寬度，就是晶片電路圖上兩條金屬線路間的最小距離（線距）；「要黏，又不能太黏」，胡呈祥點出次微米製程的難處。