Internal Photoemission Spectroscopy of Metal Gate∕High-k∕Semiconductor Interfaces

Abstract

Internal photoemission (IPE) spectroscopy is a powerful technique for investigating electronic properties of inhomogeneous interfaces of hetero-structures. Two of the most important aspects of IPE measurements involve threshold spectroscopy and photoelectron yield spectroscopy. In the first measurement type, IPE is used to determine the barrier heights at the interfaces while the second deals with photoemission of carriers (electrons and holes) with the energies above and below the barrier. We will present a brief description of the IPE principle upon which the extraction of the interfacial energy thresholds or barrier heights is based. The details of our IPE experiment setup will be also presented. For applications, in this report we will focus mainly on the first aspect of IPE where we determine the barrier heights of a technologically important class of materials which includes various metal-high-k insulator-semiconductor structures.

Assessment of Energy Barriers Between ZrCuAlNi Amorphous Metal and Atomic Layer Deposition Insulators Using Internal Photoemission Spectroscopy

“…IPE measurements were performed both at the National Institute of Standards and Technology and on a similar system built at Oregon State University. Details of this system are described elsewhere . Bias was applied to the bottom ZrCuAlNi electrode and the top Al electrode was grounded.…”

“…The IPE yield ( Y ) is defined as photocurrent normalized to the incident photon flux. The spectral threshold ( φ thresh ) of the IPE quantum yield is found using a linear extrapolation of a Fowler plot of Y 1/2 versus hν to the x ‐axis . The portion of the Y 1/2 ( hν ) plot used for determination of φ thresh , referred to as the extraction window, can significantly affect the final extracted barrier height ( φ Bn ).…”

Internal Photoemission Spectroscopy Measurements of the Energy Barrier Heights between ALD SiO2and Ta-Based Amorphous Metals

“…1, Y = (I ph * hν) / P ph [1] where P ph is the power of the light incident on the sample, as measured by a silicon photodiode. The next step in data analysis was to determine spectral thresholds (Φ thresh ) from plots of Y 1/2 versus hν (9,10), where Y 1/2 was used to account for the energy distribution at a metal interface. Spectral thresholds were found using an algorithm to find the largest region of the Y 1/2 curve with the highest linearity, as determined from the R 2 value of a linear regression.…”

Comparison on the Physical & Chemical Characteristics in Surface of Polished Wafer and Epi-Layer Wafer

“…[1][2] High-k 유전막 물질은 높은 유전 상수를 이용하여 상대적으로 두꺼운 막 두께 에도 불구하고 낮은 equivalent oxide thickness(EOT) 값 과 동일 EOT에서 SiO 2 절연막에 대비하여 낮은 누설 전 류 밀도를 갖기 때문에 기존 게이트 절연 산화막인 SiO 2 를 대체하고자 사용되고 있다. 3) 따라서, 고유전체 형성 을 위해 기존에 존재하는 SiO 2 를 확실히 제거시키기 위 해서 뿐만 아니라 실리콘 웨이퍼와 high-k 물질간 계면 에서의 잔류한 오염 물질은 결함을 발생시키는 불순물 이 되기 때문이기에 이를 효과적으로 제거하기 위한 세 정 공정이 필수적으로 수행되어야 한다. 최근에는 실리 콘 웨이퍼의 구경이 대구경화 됨에 따라 세정 횟수가 증 가하였으며 세정 과정에 사용되는 세정액 양 또한 증가 함에 소자 생산 원가가 증가하게 되며, 세정 공정에 사 용된 세정액 처리 비용 또한 증가하게 되어 효과적인 세 정액 선정이 필요한 상황이다.…”