CMP Evaluation Substrate With Varying Groove Depths
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Solution Overview
Problem
Current CMP technologies face challenges in evaluating the influence of dimples and bumps caused by dishing and erosion in low-layer wiring, leading to difficulties in achieving optimal CMP conditions for multi-layer wiring, which affects the flatness and removability of Cu residue, thereby complicating the process and reducing development efficiency and yield.
Innovation Solution
An evaluation substrate with varying groove depths is used to simulate the CMP process, allowing for the assessment of CMP conditions by comparing dishing amounts and Cu residue status across different groove depths, enabling the determination of suitable CMP conditions that prevent excessive polishing or residue shortage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If over-polishing is prolonged to remove Cu residue in dimple portions, then removability of Cu residue is improved, but dishing amount increases and flatness deteriorates
Solution Approach 1:
The patent forms an insulation layer with a thickness that is at least half the depth of the wiring groove before completing the CMP process. This preliminary insulation layer acts as a protective cushion during over-polishing, preventing excessive removal of the Cu film in dimple portions while still allowing complete removal of Cu residue. The insulation layer is formed in advance to anticipate and prevent the harmful effect of over-polishing on flatness.
2Reliability
If polishing speed of barrier film and Cu film is set to 1:1 to simultaneously polish remaining Cu film, then removability of Cu residue is improved, but polishing amount of Cu increases and flatness declines
Solution Approach 1:
The patent changes the polishing parameters by setting the polishing speed of the barrier film to be faster than that of the Cu film (specifically, the insulation layer polishing speed is controlled to be 0.5-2.0 μm/min while Cu film polishing speed is 0.1-0.5 μm/min). This parameter change allows the insulation layer to be removed at a controlled rate that prevents excessive Cu removal, thereby maintaining flatness while still achieving complete Cu residue removal.
3Adaptability or versatility
If multiple wiring layers are formed with CMP process, then multi-layer wiring functionality is achieved, but dishing and erosion accumulate and make it difficult to form subsequent wirings as designed
Solution Approach 1:
The patent forms an insulation layer with sufficient thickness (at least half the wiring groove depth) before each CMP process for subsequent wiring layers. This preliminary insulation layer compensates for the cumulative dishing and erosion effects from previous layers, providing a fresh, flat starting surface for each new wiring layer formation. This allows multiple wiring layers to be formed with consistent precision despite the cumulative effects of repeated CMP processes.
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 simplifies the evaluation of CMP conditions, improves development efficiency, enhances the removability of Cu residue, and ensures the formation of multi-layer wiring with optimal flatness and reduced wiring resistance, thereby increasing production yield and performance.
Implementation Method 1
CMP (Chemical Mechanical Polishing)
Data Source
AI summary
The CMP technology is provided for a damascene wiring structure having a plural-layer wiring that is excellent in flatness and resolvability of Cu residue. An evaluation substrate is provided for evaluating the condition of a CMP that is employed for configuring a semiconductor device having a plurality of wirings in a vertical direction, and the evaluation substrate comprises: a substrate; a first groove formed on the substrate; a second groove formed on the substrate; and wiring material provided in the first groove and the second groove, wherein a depth of the second groove is shallower than that of the first groove.