金屬污染對於二氧化鉿薄膜介電層

Abstract

在半導體製程日漸微小化，以二氧化矽當作介電層已經面臨需要找新的介電層材料來替換，本論文以目前最受重視且溫度穩定性高的二氧化鉿(HfO2)高介電常數材料，使用於前段製程時的金屬污染問題進行研究。 本論文假設化學清洗溶液發生了鉿金屬離子污染，以金氧半導體(MOS)電容做模擬，量測其平帶電壓等特性探討其污染的狀況並探討鉿金屬離子對P/N接面可能之污染。 實驗結果顯示，在稀釋氫氟酸和氨水:過氧化氫:水的混合溶液(APM)兩種溶液的污染中，氨水:過氧化氫:水的混合溶液(APM)污染是比較明顯的，而晶片浸過污染的氨水:過氧化氫:水的混合溶液(APM)再浸乾淨的稀釋氫氟酸會有電性上的改善；假如在金氧半導體製程中使用了二氧化鉿來當作介電層，就應該在做離子佈值前將多餘的二氧化鉿去除，可以避免其二氧化鉿內的污染物，因離子佈植製程而影響到接面的特性。

The manufacturing process of semi-conductors has gradually minimized. The using silicon dioxide as a dielectric layer has no longer met the require- ments of semi-conductor industries and faced the problem of replacing with a new material. The thesis is based on the idea of using HfO2, a high dielectric and stable material, and carry out researches on metal pollution during the pr- eceding process phase.

The thesis hypothesizes that the chemical solution has created Hafnium pollution and uses Metal-Oxide-Semiconductor (MOS) capacity as mimic to measure its features of flat-band voltage. It also tries to discuss the possible pollution of Hafnium to P/N connecting surface.

According to the result, of the pollution in two solutions, which are diluted hydrofluoric acid and APM, the pollution level in APM is more obvious. The chips that have been dipped in clean diluted hydrofluoric acid after being dipped into the APM have improvement in electric conductivity. During the MOS man- ufacturing process, if we use hafnium dioxide as the conductivity layer, we sho- uld get rid of excessive hafnium dioxide before the ion implantation. This can prevent the feature of connection-level from being affected by the pollutants in hafnium dioxide by the ion implantation manufacturing process.