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IMPROVEMENT IN ELECTRICAL PROPERTIES OF MULTICOMPONENT OXIDE CAPACITORS BY STUFFING ELECTRODES WITH OXYGEN PLASMA

IP.com Disclosure Number: IPCOM000009568D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Sep-03
Document File: 3 page(s) / 137K

Publishing Venue

Motorola

Related People

Peir Chu: AUTHOR [+2]

Abstract

High/medium dielectric constant materials such as Ba,,,Sr,.,TiO, (BST), SrTiO, (STO), SrBi;Ta,O, (SBT) or Ta,O, have been considered as materials of potential for high density (> 1 Gbit) DRAM, thin gate oxide, and non-volatile memory applications.

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Developments Technical 0 M MOTOROLA

  IMPROVEMENT IN ELECTRICAL PROPERTIES OF MULTICOMPONENT OXIDE CAPACITORS BY STUFFING ELECTRODES WITH OXYGEN PLASMA

by Peir Chu and Sufi Zafar

INTRODUCTION RESULTS AND DISCUSSION

  High/medium dielectric constant materials such as Ba,,,Sr,.,TiO, (BST), SrTiO, (STO), SrBi;Ta,O, (SBT) or Ta,O, have been considered as materials of potential for high density (> 1 Gbit) DRAM, thin gate oxide, and non-volatile memory applications.

  It has been discovered that resistance degrada- tion, which is characterized as a continuous increase in leakage current under service poten- tial, is the most important mechanism that causes reliability failure m these materials.

  Our internal data indicate that loss of oxygen from the dielectrics (oxygen vacancies) is the dominant factor that results in resistance degrada- tion. In order to prevent the loss of oxygen, inter- face engineering between the electrode and dielectric is important to control the loss of oxy- gen from the dielectrics.

  A PVD process is used to prepare BST dielec- tric with Pt electrodes. A typical process parame- ters for the PVD BST process are: 0.5-l .2 kW, 5- 10 mTorr, and a Ar/02 ratio from O-50%. The thickness of BST can be changed from 4 nm to 200 nm. In order to stuff oxygen into BSTlPt interface Pt electrodes were placed into a oxygen plasma chamber such as Applied Materials Centura MxP+ etcher at an appropriate power for a short period of time.

  Figure 1 shows the Auger Spectroscopy results of surface oxygen content and Pt thickness as a function of time. Plasma power in the range of 50W to 2 kW were tested but only the results at 200 W are displayed. As can be seen in this flg- ure, surface oxygen content saturates rapidly after 60 set of treatment and the Pt electrode does not show detectable loss due to plasma etching. Longer process time greater than 100 set results in significant Pt loss and should be avoided.

0 200 400 600

Time (set)

Fig. 1 Surface oxygen content and Pt thickness as function of plasma treatment time in a MxP+ etch chamber. The plasma power is 200W in this case.

c) Motomla. 1°C. ,999 266 September 1999

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MOTOROLA Technical Developments

  In order to evaluate the effectiveness of the significant difference between capacitors prepared oxygen treatment on the electrical properties of
BST capacitors, 3 different capacitors were pre-

by baseline Pt electrodes and oxygenated TE and

BE electrodes. The capacitors with oxygenated Pt bottom electrode shows a slightly higher dielectric

constant. Figure 3 shows the leakage current

between ca...