Non-Uniform Collimator for Sputtering Film Uniformity
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Solution Overview
Problem
In semiconductor device manufacturing, the collimate sputtering technique leads to non-uniform thin film thickness distribution across larger wafers, causing issues like variations in resistance and junction leaks, which necessitate premature target replacement, reducing the use efficiency of sputtering apparatuses.
Innovation Solution
A sputtering apparatus with a collimator having a thinner inner region and a thicker peripheral part, ensuring consistent film deposition by adjusting the aspect ratios and shapes of through holes to optimize the entry of sputtered particles, thereby improving film uniformity and target utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional collimator with uniform thickness is used in collimate sputtering, then the aspect ratio of through holes can be controlled, but non-uniform thin film thickness distribution occurs across larger wafers, causing variations in resistance and junction leaks
Solution Approach 1:
The collimator is designed with non-uniform thickness distribution, where the central region has a first thickness and the peripheral region has a second thickness different from the first. This local variation in thickness allows different regions of the collimator to control the aspect ratios of through holes differently, compensating for the non-uniform sputtered particle distribution across the wafer surface and achieving uniform thin film thickness
2Productivity
If the integrated usage of the target increases, then productivity improves, but thin films deposited over the central part of the wafer become gradually thinner than those over the peripheral part, deteriorating film uniformity
Solution Approach 1:
By making the collimator thickness non-uniform with the central region having a different thickness than the peripheral region, the invention creates local variations in the aspect ratios of through holes. This allows the central region to maintain better film thickness control even as target usage increases, preventing the deterioration of film uniformity that normally occurs with extended target life
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 configuration enhances the uniformity of thin films, reduces variations in resistance and junction leaks, and increases the use efficiency of the sputtering apparatus by maintaining consistent film thickness across the wafer, even with increased target usage.
Implementation Method 1
the sputtering apparatus is widely used in a process of depositing a conductive thin film for an integrated circuit over a semiconductor wafer (hereafter, also simply called a 'wafer')
Implementation Method 2
a disc-like member with numbers of through holes called a collimator is arranged between a wafer and a target provided in a sputtering chamber. The collimate sputtering technique is the one in which sputtered particles entering a main surface of the wafer obliquely from the target is reduced by the collimator and sputtered particles having many vertical components are allowed to enter the wafer
Data Source
AI summary
Reliability of a semiconductor device is improved, and use efficiency of a sputtering apparatus is increased. When depositing thin films over a main surface of a semiconductor wafer using a magnetron sputtering apparatus in which a collimator is installed in a space between the semiconductor wafer and a target installed in a chamber, a region inner than a peripheral part of the collimator is made thinner than the peripheral part. Thus, it becomes possible to suppress deterioration in uniformity of the thin film in a wafer plane, which may occur as the integrated usage of the target increases.