Browse Prior Art Database

Method of Making Via Contact Holes With Controlled Slopes

IP.com Disclosure Number: IPCOM000039821D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Brown, LM: AUTHOR [+3]

Abstract

A process for providing via contact holes having controlled slopes in Boron Phosphorus Silicon Glass (BPSG) is described. A layer of photoresist 10 is patterned to define an image having a width A (Fig. 1). Note that the sidewalls of the photoresist are nearly vertical. Then a brief anisotropic etch is carried out to form a small "notch" 14 in the BPSG 10. Then the structure is treated in a plasma comprised of 40-70% O2, with the balance CF4, at a pressure-to-power density ratio of 0.4 to 1.0 Torr/Watt-cm2 . It has been determined that with this combination of parameters the photoresist will be horizontally eroded during the etch, so that the resulting vias have a controllable slope. In general, the slope increases with increasing O2 concentration and decreasing pressure-to-power density ratio. As shown in Fig.

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Method of Making Via Contact Holes With Controlled Slopes

A process for providing via contact holes having controlled slopes in Boron Phosphorus Silicon Glass (BPSG) is described. A layer of photoresist 10 is patterned to define an image having a width A (Fig. 1). Note that the sidewalls of the photoresist are nearly vertical. Then a brief anisotropic etch is carried out to form a small "notch" 14 in the BPSG 10. Then the structure is treated in a plasma comprised of 40-70% O2, with the balance CF4, at a pressure-to-power density ratio of 0.4 to 1.0 Torr/Watt-cm2 . It has been determined that with this combination of parameters the photoresist will be horizontally eroded during the etch, so that the resulting vias have a controllable slope. In general, the slope increases with increasing O2 concentration and decreasing pressure-to-power density ratio. As shown in Fig. 2, the photoresist 12 will define an opening of a width B, B > A, at the completion of this etch step. Note that the sidewalls of photoresist 12 are still substantially vertical. Moreover, note that the notch 14 (Fig. 2), approximately A in size, is reproduced at the bottom of the via, insuring that the width of the contact hole at the portion of the via that exposes the underlying materials is also about A in size.

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