Chartered Semiconductor Manufacturing Ltd (corporation)

Wen Jun Liu

Mei Sheng Zhou

Pei Ching Lee

Simon Yew-Meng Chooi

Raymond Joy

A method for dry plasma selective etching of a pattern in a silicon nitride dielectric layer formed over a semiconductor substrate employed within a microelectronics fabrication. There is provided a semiconductor substrate having formed thereupon a pad oxide layer over which is formed a silicon nitride dielectric layer. There is formed over the substrate a patterned photoresist etch mask layer. There is then selectively etched the pattern of the photoresist etch mask layer into the silicon nitride layer employing a four-step etching process with three plasma etching environments which include; (1) a &ldquo;break-through&rdquo; etching step; (2) a &ldquo;bulk&rdquo; etching step to remove a majority of the silicon nitride layer and a &ldquo;buffer&rdquo; etching step to remove the remainder of the silicon nitride layer; and (3) an &ldquo;over-etch&rdquo; step to complete removal of silicon nitride without excessive etching of underlying material. These steps comprise the selective etching of the patterned silicon nitride layer while maintaining control of critical dimensions, with attenuated microloading and over-etching of underlying material.

Multiple-step plasma etching process for silicon nitride

An improved method for removing a photoresist mask from an etched aluminum pattern after etching the pattern in a chlorine containing plasma has been developed. The method is a five step process, in which the first step is in a microwave generated plasma containing O,and H,O; the second step is in a microwave generated plasma containing O,and N,; the third step is in a microwave generated plasma containing H,O; the fourth step is in a microwave generated plasma containing O,and N,; and the fifth step is in a microwave generated plasma containing H,O. The first step which initiates removal of photoresist while simultaneously beginning the passivation process causes residue-free removal of photoresist following etching of aluminum or aluminum-copper layers in chlorine bearing etchants.

Post metal etch photoresist strip method

A novel anisotropic plasma etching process for forming patterned silicon nitride (Si.sub.3 N.sub.4) layers with improved critical dimension (CD) control while minimizing the Si.sub.3 N.sub.4 footing at the bottom edge of the Si.sub.3 N.sub.4 pattern is achieved. A pad oxide/silicon nitride layer is deposited on a silicon substrate. A patterned photoresist layer is used as an etching mask for etching the silicon nitride layer. By this invention, a chlorine (Cl.sub.2) breakthrough plasma pre-etch forms a protective polymer layer on the sidewalls of the patterned photoresist and removes residue in the open areas prior to etching the Si.sub.3 N.sub.4. The Si.sub.3 N.sub.4 is then aniso-tropically plasma etched using an etch gas containing SF.sub.6. The polymer layer, formed during the Cl.sub.2 pre-etch, reduces the lateral recessing of the photoresist when the Si.sub.3 N.sub.4 is etched, and results in improved patterned Si.sub.3 N.sub.4 profiles with reduced CD bias, and minimizes Si.sub.3 N.sub.4 footings at the bottom edge of the Si.sub.3 N.sub.4 pattern.

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Singapore, Singapore

Wen Jun Liu