Semiconductor Voids via Hard Mask Etch Stop
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Solution Overview
Problem
Traditional low-k dielectric materials in semiconductor devices fail to adequately reduce capacitive coupling as conductive feature density increases, and void formation in interconnect layers poses challenges in controlling void dimensions and risks damage to adjacent conductive features.
Innovation Solution
A method involving the formation of voids in semiconductor device layers by using a hard mask to create openings, followed by the deposition of a barrier layer and an etch stop layer, and then sealing these openings with a second dielectric layer to form voids that reduce parasitic capacitance, while protecting conductive features from misalignment and damage during patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If voids are formed in dielectric layers to reduce parasitic capacitance, then capacitive coupling is reduced, but controlling void dimensions becomes difficult and conductive features may be damaged during subsequent patterning
Solution Approach 1:
The patent applies preliminary action by forming a hard mask layer and patterning it to define void regions before the actual void formation process. This pre-defined mask structure guides subsequent etching and material deposition, ensuring precise void dimensions are achieved without damaging conductive features during later patterning steps.
Solution Approach 2:
The patent introduces intermediate layers including a hard mask layer, barrier layer, and etch stop layer that mediate between the void formation process and the final device structure. These intermediary layers protect conductive features during processing and enable precise control of void dimensions through selective etching and deposition.
2Object-generated harmful factors
If voids are formed in dielectric layers to reduce parasitic capacitance, then capacitive coupling is reduced, but conductive features adjacent to voids may be damaged during subsequent patterning
Solution Approach 1:
The patent applies beforehand cushioning by forming an etch stop layer and barrier layer prior to void formation and subsequent patterning steps. These protective layers act as a cushion that prevents direct exposure of conductive features to aggressive etching processes, thereby preventing damage while allowing voids to be formed for reducing parasitic capacitance.
Solution Approach 2:
The barrier layer and etch stop layer serve as intermediary protective elements between the void formation process and conductive features. These intermediaries enable the patterning process to proceed without directly exposing and potentially damaging the conductive features adjacent to voids.
3Ease of manufacture
If traditional low-k dielectric materials are used in interconnect layers, then manufacturing is simpler, but capacitive coupling cannot be sufficiently reduced as conductive feature density increases
Solution Approach 1:
The patent applies local quality by introducing voids (air gaps with k≈0) at specific locations between conductive features in the dielectric layer, while maintaining the low-k dielectric material in other regions. This localized modification of dielectric properties allows sufficient reduction of parasitic capacitance in high-density interconnect regions without requiring complete replacement of the dielectric material, thus balancing manufacturing simplicity with electrical performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces parasitic capacitance and allows for precise control of void dimensions, minimizing damage to conductive features and improving the manufacturing process by using a robust etch stop layer to prevent unintended etching during subsequent processing steps.
Implementation Method 1
a second dielectric layer is formed over the conductive lines. Forming the second dielectric layer seals the opening to form a void
Data Source
AI summary
A method embodiment includes forming a hard mask over a dielectric layer and forming a first metal line and a second metal line extending through the hard mask into the dielectric layer. The method further includes removing the hard mask, wherein removing the hard mask defines an opening between the first metal line and the second metal line. A liner is then formed over the first metal line, the second metal line, and the dielectric layer, wherein the liner covers sidewalls and a bottom surface of the opening.