Sidewall Image Transfer for Multiple Critical Dimensions
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Solution Overview
Problem
Conventional sidewall image transfer processes in semiconductor manufacturing can only create one type of spacer with the same width, limiting the transfer of multiple critical dimensions of device patterns, which is insufficient for modern semiconductor device requirements.
Innovation Solution
A method involving the formation of a multi-level dielectric layer with regions of different thicknesses over mandrels, followed by directional etching to create spacers of varying widths, and subsequent transfer of bottom images into underlying layers, allowing for the creation of multiple critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a blanket deposition of spacer making material is performed after mandrel litho development, then spacers can be formed through directional etching, but only one type of spacer with the same width is created, limiting the transfer of multiple critical dimensions
Solution Approach 1:
The patent applies local quality by creating a multi-level dielectric layer where different regions have different thicknesses. This is achieved by depositing a conformal dielectric layer and then selectively removing portions through etching to create regions with varying thicknesses. When spacers are formed from this multi-level layer, each region produces spacers with different widths, enabling multiple critical dimensions to be transferred simultaneously. This resolves the contradiction by making the spacer making material non-uniform in a controlled manner to achieve diverse spacer widths.
Solution Approach 2:
The patent introduces an additional dimension (vertical thickness variation) to the traditionally uniform dielectric layer. By creating a multi-level dielectric structure with varying thicknesses in the vertical dimension, the process enables horizontal variation in spacer widths. This dimensional transformation allows a single blanket deposition to produce multiple spacer widths, resolving the contradiction between process simplicity and spacer diversity.
2Ease of manufacture
If conventional sidewall image transfer is used, then the process is simple and straightforward, but it cannot meet the market demand for ever increasing device density and multiple critical dimensions
Solution Approach 1:
The patent applies preliminary action by pre-forming a multi-level dielectric layer with specific thickness variations before the spacer formation step. This preliminary structuring of the dielectric layer embeds the information for multiple critical dimensions into the spacer making material itself, so that when spacers are formed through conventional directional etching, multiple widths are automatically produced. This maintains process simplicity while enabling high device density.
Solution Approach 2:
The patent changes the physical parameter of the dielectric layer from uniform thickness to variable thickness across different regions. By controlling the thickness parameter of the spacer making material in different areas, the process generates spacers with different widths from a single blanket deposition. This parameter variation enables multiple critical dimensions to be achieved without complicating the overall manufacturing process.
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
Enables the formation of semiconductor devices with multiple critical dimensions, enhancing device density and pattern complexity, addressing the limitations of conventional sidewall image transfer techniques.
Implementation Method 1
etching the plurality of regions of the multi-level dielectric layer into spacers by applying a directional etching process
Implementation Method 2
forming a substantially conformal dielectric layer over the plurality of mandrels
Data Source
AI summary
Embodiment of the present invention provides a method of forming a semiconductor device in a sidewall image transfer process with multiple critical dimensions. The method includes forming a multi-level dielectric layer over a plurality of mandrels, the multi-level dielectric layer having a plurality of regions covering the plurality of mandrels, the plurality of regions of the multi-level dielectric layer having different thicknesses; etching the plurality of regions of the multi-level dielectric layer into spacers by applying a directional etching process, the spacers being formed next to sidewalls of the plurality of mandrels and having different widths corresponding to the different thicknesses of the plurality of regions of the multi-level dielectric layer; removing the plurality of mandrels in-between the spacers; and transferring bottom images of the spacers into one or more layers underneath the spacers.