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Method for pore sealing by selective polymer growth on mixed substrates

IP.com Disclosure Number: IPCOM000030172D
Publication Date: 2004-Jul-30
Document File: 2 page(s) / 9K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for pore sealing by selective polymer growth on mixed substrates. Benefits include improved functionality and improved performance.

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Method for pore sealing by selective polymer growth on mixed substrates

Disclosed is a method for pore sealing by selective polymer growth on mixed substrates. Benefits include improved functionality and improved performance.

Background

              Induced densification of exposed inter-layer dielectric (ILD) surfaces results in damage to the film that can increase the dielectric constant (k) significantly. Conventional densification processes have poor depth control and have directionality that preferentially densifies the surface rather than the important exposed sidewalls after etch. Thin-film deposition processes cannot seal pores at <10 nm, which impacts the dielectric constant too much at feature sizes <45 nm. Insulating sealing layers insulate the bottom of the vias, causing opens that significantly curtail process yields. Thick metal barriers impact performance by driving via resistance values to unacceptable levels.

              Using porous low-k materials to fabricate semiconductor devices leads to the diffusion of wet chemicals and process gases through the film and to poor metal barrier step coverage. It also prevents atomic layer deposition (ALD) processes to deposit barrier metal layers. Sealing pores that are cut open during etch can mitigate these problems.

              Conventionally, pore sealing has been addressed primarily by three approaches:

1.           Induced densification of exposed ILD surfaces, for example, with plasma or e-beam

2.           Depositing a thin insulating film such as SiC over the pores

3.           Depositing a thick barrier metal over the pores

General description

      The disclosed method seals pores in low-k dielectric materials by pretreating the surface and selectively growing a thin polymer layer over them.

              The key elements of the disclosed method include:

•             Modifying the surface of the ILD to promote selective deposition of the pore sealant

•             Sealing pores by selectively depositing a polymer over an ILD surface

•             Leaving the via bottoms open so that electrical contact is kept during metal deposition

•             Using surface chemistry to control the film thickness, so that the impact to the effective dielectric constant value is minimized, and small feature sizes are not completely filled

Advantages

              The disclosed method provides advantages, including...