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Method for Making Devices Having Reduced Field Gradients at Junction Edges

IP.com Disclosure Number: IPCOM000037800D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

El-Kareh, B: AUTHOR [+3]

Abstract

By using polycrystalline (poly-Si) filled shallow trenches as doping sources, depth of uniform doping at junction edges is controlled to reduce field gradients near the junction edges. Short channel and device saturation effects, e.g., hot electron injection, are thereby reduced without degrading device transconductance.

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Method for Making Devices Having Reduced Field Gradients at Junction Edges

By using polycrystalline (poly-Si) filled shallow trenches as doping sources, depth of uniform doping at junction edges is controlled to reduce field gradients near the junction edges. Short channel and device saturation effects, e.g., hot electron injection, are thereby reduced without degrading device transconductance.

Referring to the figure, normal processing is used to create gate conductor 2 having an insulating coating 4 on its top and edges. Thin gate insulator 6 is between gate conductor 2 and substrate silicon 8. Substrate 8 is exposed in contact regions 10 and 12, the regions between insulator 4 and recessed oxide areas 14 and 16.

Departing from normal processing, shallow trenches are reactive ion etched (RIE) in the contact regions 10 and 12. Intrinsic poly-Si is then deposited over the entire surface. Following a planarizing polish to the level of the top of insulator 4, RIE is used to remove additional poly-Si until its top surface is below the level of the top surface of recessed oxide areas 14 and 16. Thus, poly-Si 18 exists only in contact regions 10 and 12. P-type dopant is then implanted into poly-Si 18 in regions 10 and 12 through a first block mask, and N-type dopant is implanted in other contact areas exposed through a second block mask to construct complementary metal oxide silicon (CMOS) integrated circuit devices. Following deposition of a transition metal, a heat...