shiver / chill down / up one's spine
/ʃˈɪvɚɹ ɔːɹ tʃˈɪl dˌaʊn ɔːɹ ˌʌp wˈʌnz spˈaɪn/
phrasea sudden physical reaction to a strong emotional experience, such as fear, excitement, or awe, typically characterized by a cold or trembling sensation running down the back