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Systematic survey and property control of high-dielectric-constant thin films for gate insulators of next generation MOSFETs

下一代MOSFET栅极绝缘体用高介电常数薄膜的系统研究和性能控制

基本信息

批准号：
12450121
负责人：
TOKUMITSU Eisuke
金额：
$ 10.18万
依托单位：
TOHOKU UNIVERSITY (2002)Tokyo Institute of Technology (2000-2001)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The objective of this study is to obtain high-dielectric-constant (high-k) thin films on Si which have an SiO_2 equivalent oxide thickness (EOT) of less than 2 nm for gate insulator application of next generation MOSFETs. First, various high-k thin films, such as ZrO_2, HfO_2, CeO_2, Y_2O_3, La_2O_3, Pr_2O_3, Sm_2O_3 and so on, were fabricated on Si substrate by the molecular beam deposition (MBD) technique and characterized. For HfO_2 and La_2O_3 thin films, EOT values of 0.88 nm and 1.5 nm were obtained, respectively. It was also found that the La_2O_3 film was easily damaged by the humidity in the air. Hence, to suppress this damage, gate electrodes were fabricated as soon as the La_2O_3 film was deposited. With this technique, we fabricated MOSFETs using a La_2O_3 gate insulator which had an EOT of 0.88 nm. Normal transistor operation was confirmed for the fabricated devices. Next, metalorganic chemical vapor deposition (MOCVD) technique was developed for HfO_2 thin films growth on Si substrates. Hf[N(CH_3)_2]_4 and Hf[N(C_2H_5)_2)]_4 which contain no oxygen nor chlorine as well as conventional Hf(O-t-C_4H_9)_4 were used as Hf precursors. Either O_2 or H_2O was used as an oxidant gas. We fabricated HfO_2 thin films on Si substrates by alternatively introducing Hf precursor and oxidant gas and found that the residual impurity concentrations and leakage current density are much lower for the HfO_2 films fabricated with H_2O than HfO_2 films fabricated with O_2. An EOT of the HfO_2 films grown with Hf[N(C_2H_5)_2]_4 and H_2O was as small as 1.8 nm and the leakage current density of the films at 1 V is less than 10^<-5> A/cm^2.

本研究的目的是在 Si 上获得高介电常数（高 k）薄膜，其 SiO_2 等效氧化物厚度（EOT）小于 2 nm，用于下一代 MOSFET 的栅极绝缘体应用。首先，采用分子束沉积(MBD)技术在Si衬底上制备了ZrO_2、HfO_2、CeO_2、Y_2O_3、La_2O_3、Pr_2O_3、Sm_2O_3等各种高k薄膜并进行了表征。对于HfO_2和La_2O_3薄膜，分别获得0.88 nm和1.5 nm的EOT值。研究还发现La_2O_3薄膜很容易被空气中的湿度损坏。因此，为了抑制这种损害，一旦沉积La_2O_3膜就制作栅电极。通过这种技术，我们使用 EOT 为 0.88 nm 的 La_2O_3 栅极绝缘体制造了 MOSFET。已确认所制造的器件的晶体管正常工作。接下来，开发了用于在Si衬底上生长HfO_2薄膜的金属有机化学气相沉积（MOCVD）技术。使用不含氧和氯的Hf[N(CH_3)_2]_4和Hf[N(C_2H_5)_2)]_4以及常规的Hf(O-t-C_4H_9)_4作为Hf前体。使用O_2或H_2O作为氧化剂气体。我们通过交替引入Hf前驱体和氧化剂气体在Si衬底上制备了HfO_2薄膜，发现用H_2O制备的HfO_2薄膜的残余杂质浓度和漏电流密度比用O_2制备的HfO_2薄膜低得多。用Hf[N(C_2H_5)_2]_4和H_2O生长的HfO_2薄膜的EOT小至1.8nm，并且薄膜在1V下的漏电流密度小于10^-5A/cm^2。