1. Technical Field
The invention relates generally to integrated circuit fabrication, and more particularly, to an integrated circuit chip, a related chip package and method that provide an intermediate dielectric constant material at an interlevel dielectric (ILD) layer directly below a silicon dioxide (SiO2) based dielectric material to reduce stress in back-end-of-line layers.
2. BACKGROUND ART
As the integrated circuit industry continues to drive toward reduced feature size one of the challenges is maintaining the structural reliability relative to chip package interactions. Chip package interactions include structural interactions between multi-level interconnect structures (referred to as back-end-of-line (BEOL) layers and including all layers after a first metal (M1) layer) of a chip, interconnections between the chip and substrates. Conventional BEOL layers require more fragile low dielectric constant (low-k) dielectric materials having coefficient of thermal expansion (CTE) that differ significantly from the substrates (e.g., organic laminate) to which they are coupled.
An integrated circuit (IC) chip and related package are disclosed including a first interlevel dielectric (ILD) layer(s) including an ultra low dielectric constant (ULK) material, a second ILD layer(s) including a silicon dioxide (SiO2) based dielectric material above the first ILD layer(s), and a transitional ILD layer including an intermediate dielectric constant material. The transitional ILD layer is positioned directly below a lowermost one of the second ILD layer(s), excepting any isolation layer, which represents the layer most susceptible to failure. The intermediate dielectric constant material can have a dielectric constant and an elastic modulus greater than that of the ULK material and less than that of the SiO2 based dielectric material. Hence, the intermediate dielectric constant provides adequate electrical properties, but also absorbs more of the stress than the typical ULK material, which reduces the likelihood of failure. A method of forming the IC chip is also disclosed.
A first aspect of the invention provides a method of forming a multi-level interconnect structure of an integrated circuit chip, the method comprising the steps of: forming at least one first interlevel dielectric (ILD) layer including an ultra low dielectric constant (ULK) material; forming at least one second ILD layer including a silicon dioxide (SiO2) based dielectric material, the at least one second ILD layer positioned above the at least one first ILD layer; and forming, immediately prior to a lowermost one of the at least one second ILD layer, excepting any isolation layer, a transitional ILD layer including an intermediate dielectric constant material.
A second aspect of the invention provides an integrated circuit chip comprising: at least one first interlevel dielectric (ILD) layer including an ultra low dielectric constant (ULK) material; at least one second ILD layer including a silicon dioxide (SiO2) based dielectric material, the at least one second ILD layer positioned above the at least one first ILD layer; and a transitional ILD layer including an intermediate dielectric constant material, the transitional ILD layer, excepting any isolation layer, positioned directly below a lowermost one of the at least one second ILD layer.
A third aspect of the invention provides an integrated circuit chip package comprising: a substrate; an integrated circuit (IC) chip including a multi-level interconnect structure including: at least one first interlevel dielectric (ILD) layer including an ultra low dielectric constant (ULK) material, at least one second ILD layer including a silicon dioxide (SiO2) based dielectric material, the at least one second ILD layer positioned above the at least one first ILD layer, and a transitional ILD layer including an intermediate dielectric constant material, the transitional ILD layer, excepting any isolation layer, positioned directly below a lowermost one of the at least one second ILD layer; and a plurality of electrically conductive interconnections between the substrate and the integrated circuit chip.
The illustrative aspects of the present invention are designed to solve the problems herein described and other problems not discussed.
These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:
It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.
Referring to
IC chip 102 includes a multi-level interconnect structure 120 according to one embodiment of the invention. Multi-level interconnect structure 120 includes at least one first interlevel dielectric (ILD) layer 122 (four shown) including an ultra low dielectric constant (ULK) material. Each first ILD layer 122 may also include a metal level M2-M5 and a via level V2-V5. “ULK material” is any material having a dielectric constant (k) of less than approximately 2.8, and having a relatively weak mechanical strength relative to a low dielectric constant silicon dioxide (SiO2) dielectric material of a second ILD layer(s) 124 and an intermediate dielectric constant material of a transitional ILD layer 126, each of which will be described below. For example, ULK material may have an elastic modulus of approximately 6 GPa. Each first ILD layer 122 material may be chosen to meet electrical requirements, lithographic requirements and/or material preferences. In one embodiment, first ILD layer(s) 122, other than an uppermost first ILD layer 122U, may include any dielectric material having a dielectric constant less than approximately 2.7. For example, hydrogenated silicon oxycarbide (SiCOH) generation III, porous SiCOH or other ULK material may be used. SiCOH generation III indicates a version of SiCOH exhibiting a dielectric constant of approximately 2.7, in contrast to earlier generations of SiCOH, which had higher dielectric constant values. The ULK material of uppermost first ILD layer 122U may include any dielectric material having a dielectric constant less than approximately 2.8. For example, a porous SiCOH or SiCOH generation III may be used. In one example, each 1x ILD layer 122, e.g., M2/V2-M4/V4, includes SiCOH generation III and each 2x ILD layer 122, e.g., M5/V5, includes porous SiCOH. However, other configurations are possible.
Multi-level interconnect structure 120 also includes at least one second ILD layer 124 (three shown) including a silicon dioxide (SiO2) based dielectric material. As shown in
As shown in
Turning to
In one embodiment of the invention, a method of forming a multi-level interconnect structure of an IC chip is provided. The method may be implemented using any now known or later developed fabrication processes. Based on
It should be recognized that the number of ILD layers shown is only illustrative and that the number may be changed within the scope of the invention. In addition, the terms “lowermost” and “uppermost” are meant only to provide reference for the embodiments as shown only, and are not meant to limit the invention to any particular special positioning.
The foregoing description of various aspects of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of the invention as defined by the accompanying claims.