Taiwan Semiconductor Manufacturing Comp. Ltd.

Ming-Huei Lui

Chia-Shiung Tsai

Jen-Cheng Liu

Chao-Cheng Chen

Li-Chih Chao

Mei-Hui Sung

Hun-Jan Tao

Li-chih Chao

An improved and new process for photoresist stripping for use during fabrication of semiconductor integrated circuits, which use porous low-k dielectric materials, such as OSG or HSQ, as the interlevel and intra-level insulating layers, has been developed. Photoresist stripping in microwave or rf generated plasmas in gaseous mixtures of NH and CO takes place without attack or damage to underlying layers of OSG or HSQ. Optimum results are obtained when the ratio of CO to NH is between about 0.8 and 1.2.

Method of resist stripping over low-k dielectric material

Within a dual damascene method for forming a dual damascene aperture within a microelectronic fabrication there is employed a bottom etch stop layer formed of a first material and an intermediate etch stop layer formed as a laminate of a second material having formed thereupon a third material. Within the method, the second material serves as an etch stop for the first material and the third material, which may be identical materials. Within the method, there may be etched completely through the bottom etch stop layer to reach a contact region formed there beneath while not etching completely through the intermediate etch stop layer to reach a first dielectric layer formed there beneath.

Dual damascene structure employing laminated intermediate etch stop layer

Using this special dual damascene process, interconnect conducting lines and via contacts are formed which have low parasitic capacitance (low RC time constants). The invention incorporates the use of thin etch stop or etch barrier layers. The key process steps of this invention are a special partial via hole etch and a special via hole liner. The Prior Art dual damascene processes are generally composed of a thick via etch stop layer to avoid damaging underlying Cu during via patterning, as well as, a thick trench etch stop layer to avoid via hole facet during trench patterning. Thick etch stop layers are undesirably due to high dielectric constant values compared with silicon oxide, the intermetal dielectric (IMD). Therefore, the thickness of stop-layer should be reduced to minimize the circuit (RC) time constant delay. In general, there are two main approaches for dual damascene etching. One of the main approaches use self-aligned dual damascene (SADD) etching which requires a thick trench etching stop-layer thickness. The other approach use counter-bore method which requires a thick via etching stop-layer thickness. This invention describes a novel dual damascene process which can minimize the thickness of both via and trench etching stop-layer, while avoiding deleterious damage to the underlying to and via facet profile during via and trench etching.

Dual damascene process to reduce etch barrier thickness

A new method is provided for creating the interconnect pattern for dual damascene structures. The dual damascene structure is created in two overlying levels of dielectric, a first etch stop layer is deposited over the surface of the substrate, a second etch stop layer is deposited between the two layers of dielectric. A first etch penetrates both layers of dielectric, a second etch penetrates the top dielectric layer. Before the second etch is performed, a layer of ARC is deposited. For the second etch a polymer rich etchant is used to protect the sidewalls of the opening. The second etch leaves in place a fence of material (containing C, H, F and oxide compounds) that is formed around the upper perimeter of the opening through the lower layer of dielectric. This fence protects the upper corners of the lower opening of the dual damascene structure and is removed in a two step procedure. At the completion of this two step procedure the upper corners of the lower opening of the dual damascene structure have retained a rectangular profile. A final step removes the photoresist (that has been used to create the interconnect line opening) from the surface of the second layer of dielectric while the remnants of the ARC material are also removed.

Method for improving faceting effect in dual damascene process

A method is described for cleaning freshly etched dual damascene via openings and preparing them for copper fill without damage or contamination of exposed organic or other porous low-k insulative layers. The method is entirely dry and does not expose the porous materials to contamination from moisture or solvents. The method is effective for removing all traces of residual polymer deposits from an in-process substrate wafers after via or damascene trench etching. The method employs an in-situ three-step treatment comprising a first step of exposing the electrically biased substrate wafer to a O,/N,ashing plasma to remove photoresist and polymers, a second step immediately following the first step of remove silicon nitride etch stop layers, and a final step of treating the wafer with H,/N,to remove copper polymer deposits formed during nitride removal. The H,/N,plasma is capable of removing the difficult polymer residues which are otherwise only removable by wet stripping procedures. The H,/N,plasma is not harmful to exposed porous low-k dielectric layers as well as copper metallurgy.

Fully dry post-via-etch cleaning method for a damascene process

A method for forming a dual damascene structure in a carbon-based, low-K material. The process begins by providing a semiconductor structure having a first metal pattern thereover, wherein the first metal pattern has a first barrier layer thereon. An organic dielectric layer is formed on the first barrier layer, and a hard mask layer is formed on the dielectric layer. The hard mask layer and the dielectric layer are patterned to form a trench. A second barrier layer is formed over the hard mask layer and on the bottom and sidewalls of the trench. A barc layer is formed over the second barrier layer, thereby filling the trench. The barc layer, the second barrier layer, and the dielectric layer are patterned to form a via opening, preferably using a photoresist mask. The barc layer is patterned without faceting the edges of the via opening due to the second barrier layer. The barc layer and the etch mask are removed by the dielectric layer etch. The first barrier layer and the second barrier layer are removed. A third barrier layer is formed on the bottom and sidewalls of the trench, on the sidewalls of the via opening, and on the first metal pattern through the via opening. The trench and the via opening are filled with metal to form a damascene structure.

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Ming-Huei Lui