Trench Metal Layer Deposition for Void-Free Semiconductor Structures
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Solution Overview
Problem
The miniaturization of IC devices has made it challenging to fill trenches with aluminum, often resulting in voids and surface roughness due to large grain sizes, which decreases the quality of the device.
Innovation Solution
A method involving a deposition apparatus with supporting pins and two deposition processes, where the substrate temperature is gradually increased in the first process and then filled completely in the second process, using a bias voltage unit and heat transferring gas to improve gap filling and reduce grain size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single deposition process is used to fill the trench with aluminum, then the process is simple and fast, but voids are formed within the trench and the aluminum layer has large grain size resulting in surface roughness
Solution Approach 1:
The deposition process is divided into multiple sequential deposition steps with different parameters. The first deposition step uses parameters optimized for initial aluminum layer formation, while subsequent steps use different parameters to complete the trench filling and improve surface quality, thereby resolving the contradiction between filling quality and process complexity
Solution Approach 2:
Different deposition parameters (such as deposition rate, temperature, or gas flow) are changed between deposition steps. By adjusting parameters during the deposition process, the method achieves complete trench filling with smooth surface and fine grain structure, overcoming the limitations of conventional single-parameter deposition
2Length of moving object
If the device size is miniaturized, then the IC device becomes smaller and more advanced, but it becomes increasingly difficult to fill the aluminum into the trench and voids are formed
Solution Approach 1:
The first deposition step performs preliminary aluminum layer formation before the trench is completely filled. This preliminary action creates a foundation layer that facilitates subsequent complete filling, addressing the difficulty of filling miniaturized trenches
Solution Approach 2:
The deposition process uses dynamic parameter adjustment between steps rather than static parameters. By making the deposition process adaptive and dynamic, the method successfully fills shallower and narrower trenches in miniaturized devices without forming voids
3Ease of manufacture
If the aluminum layer is formed by current deposition process, then the deposition is straightforward, but the aluminum layer has larger grain size resulting in surface roughness and spikes into underlying layers
Solution Approach 1:
The aluminum layer formation is segmented into multiple deposition steps instead of a single step. The first step forms an initial layer with certain grain structure, while subsequent steps refine the surface morphology and reduce grain size, achieving smooth surfaces without sacrificing manufacturing ease
Solution Approach 2:
The deposition process uses periodic cycles of deposition with varying parameters. By implementing periodic deposition actions with different conditions in each cycle, the method achieves fine grain size and smooth surface finish while maintaining practical manufacturability
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 method achieves a metal layer with better quality, reduced spiking into barrier layers, and improved reflectivity, effectively avoiding voids and enhancing the surface smoothness.
Implementation Method 1
A first deposition process is performed right after the substrate is placed on the supporting pins to form a metal layer in the trench
Implementation Method 2
during the first deposition process a temperature of the substrate is gradually increased to a predetermined temperature
Data Source
AI summary
A method for filling a trench with a metal layer is disclosed. A deposition apparatus having a plurality of supporting pins is provided. A substrate and a dielectric layer disposed thereon are provided. The dielectric layer has a trench. A first deposition process is performed immediately after the substrate is placed on the supporting pins to form a metal layer in the trench, wherein during the first deposition process a temperature of the substrate is gradually increased to reach a predetermined temperature. When the temperature of the substrate reaches the predetermined temperature, a second deposition process is performed to completely fill the trench with the metal layer. The present invention further provides a semiconductor device having an aluminum layer with a reflectivity greater than 1, wherein the semiconductor device is formed by using the method.