1. Field of the Invention
The present invention relates generally to the field of microelectronics fabrications, and more particularly to the field of dielectric layers employed within microelectronics fabrications.
2. Description of the Related Art
In order to fabricate microelectronics devices it is necessary to employ layers of dielectric material to electrically insulate patterned conductor material layers which serve to interconnect the devices in the microelectronics fabrication. As microelectronics devices have become more complex and densely populated, the requirements on the conductor and dielectric layers have become more stringent. The need to minimize power requirements and resistive losses has led to the employment of materials with higher electrical conductivity such as copper, for example. These conductor layers are often fabricated in complex and sophisticated configurations such as inlaid or damascene designs in order to maintain surface planarity in multi-layer structures. The conductor layer may act as a diffusion barrier towards substances emanating from other layers or, conversely, the conductor layer may require a barrier layer to protect it from deleterious substances or to protect other layers from itself.
Dielectric materials which are useful for formation of dielectric layers employed within microelectronics fabrications often are desired to have low dielectric constants to increase circuit performance. Such low dielectric constant materials as organic polymer dielectric materials or fluorine-doped silicon containing glass dielectric materials are commonly employed. Likewise, the increased circuit density and complexity has also led to multiple conductor layers and dielectric layers being fabricated into inter-level metal dielectric (IMD) layers to be able to accommodate all the requirements of increased circuit density and interconnectability. Although methods and materials are available which are satisfactory for these purposes in general, the employment of multi-level conductor layers and low dielectric constant dielectric layers is not without problems.
For example, the dielectric material selected for optimum electrical performance may require a method of formation or a composition which is incompatible with the physical or chemical properties of the conductor material with which the dielectric layer is in intimate contact.
It is thus towards the goal of forming a dielectric layer with an adjacent dielectric diffusion barrier material to protect conductor materials such as copper that the present invention is generally directed.
Various methods have been disclosed for forming conductor layers such as copper and a diffusion barrier layer upon an adjacent dielectric layer to attenuate damage to conductor material from nearby diffusing deleterious species.
For example, Cheung et al., in U.S. Pat. No. 5,785,236, disclose a method for forming aluminum or gold wire bonds to copper bonding pads. The method employs copper bonding pads supported within an interlayer dielectric which may be composed of silicon nitride,
Further, Bhattacharya et al., in U.S. Pat. No. 5,811,870, disclose a method for forming an anti-fuse structure which can be transformed from a non-conductive to a conductive state by application of a voltage across a two-layer insulator. The two-layer structure employs a dielectric layer and an injector layer. The latter employs a silicon-rich silicon oxide or silicon nitride layer.
Yet further, Cleeves et al., in U.S. Pat. No. 5,830,804, disclose a method for forming an encapsulated dielectric layer. The method employs a disposable post material over which is formed a dielectric layer which completely surrounds the post material. A second and third dielectric layer are formed over the encapsulated post and then a portion of the third layer is selectively removed to reveal the disposable post, which is then removed to form an opening in the dielectric layers.
Yet further still, Boeck et al., in U.S. Pat. No. 5,880,018, disclose a method for forming an inter-level metal dielectric (IMD) layer with reduced cross-talk. The method employs a selective placement of a low dielectric constant dielectric material with a dielectric constant equal or less than 3.5 within the IMD layer, and employs various conductor materials.
Finally, Wong et al., in U.S. Pat. No. 5,946,601, disclose a method for forming a layer which can function as a liner or barrier layer to separate a low dielectric constant dielectric layer from surrounding metal layers. The method employs a layer of amorphous hydrogenated carbon nitride and amorphous carbon nitride to separate a low dielectric constant dielectric material containing fluorine from a metal layer.
Desirable in the art of microelectronics fabrication are additional methods for forming an inter-level metal (IMD) layer within which is formed a diffusion barrier dielectric layer and employing conductor layers which are sensitive to corrosion such as copper.
It is towards this goal that the present invention is generally and more specifically directed.