Reactive Sputtering Pulse Control for Composite Film Composition
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Solution Overview
Problem
Conventional reactive sputtering apparatuses for forming composite metal compound films have limitations in controlling the composition and deposition order of films, requiring independent power control for multiple electrodes and a cylindrical substrate holder configuration that increases apparatus size and vacuum pumping requirements.
Innovation Solution
The introduction of pulse-wave conversion switches between DC power sources and sputtering electrodes, along with a programmable transmitter for independent control of pulse generation and reactive gas introduction, allows for flexible setting of electric power and timing for each electrode, enabling precise control over film composition and deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cylindrical substrate holder is rotated to deposit ultrathin films from multiple targets, then film composition can be controlled, but the passage time through sputtering and plasma regions cannot be controlled independently and apparatus size increases
Solution Approach 1:
The apparatus divides the film formation process into separate stages: a sputtering region with multiple targets and a plasma region with grid structures. This segmentation allows independent control of passage times through each region, resolving the contradiction between film composition control and apparatus complexity.
Solution Approach 2:
The substrate holder rotation speed can be dynamically adjusted to control the passage time through the sputtering region, while the plasma region exposure is controlled by grid opening/closing timing. This dynamic control enables independent adjustment of both passage times without increasing apparatus size.
2Manufacturing precision
If the substrate holder rotational speed is increased to maintain ultrathin film thickness, then a high-rating driving motor is required
Solution Approach 1:
The grid structures are opened and closed periodically to control plasma exposure timing, allowing precise film thickness control without requiring high rotational speeds. This periodic action reduces the power requirement for the driving motor while maintaining manufacturing precision.
3Ease of operation
If a cylindrical substrate holder is used to hold substrates, then the interior space becomes unnecessary and a high-rating vacuum pump is required
Solution Approach 1:
The substrate holder is extracted from the cylindrical configuration and repositioned in the plasma region. This eliminates the unnecessary interior space of the cylindrical holder, reducing the vacuum chamber volume and allowing the use of a lower-rated vacuum pump while maintaining ease of substrate handling.
4Manufacturing precision
If independent power control is provided for each sputtering electrode to set film composition, then multiple power sources are required increasing apparatus complexity
Solution Approach 1:
Multiple sputtering electrodes share a common power supply system with centralized control. The grid structures and timing control enable independent effective control of each electrode's contribution to film composition without requiring separate power sources, thus reducing apparatus complexity while maintaining manufacturing precision.
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 allows for the free setting of composite metal compound film composition and deposition order, reducing the need for high-rating motors and vacuum pumps, enabling more efficient and precise film formation with reduced apparatus size.
Implementation Method 1
two or more sputtering electrodes (18, 19) arranged to face a substrate (S) placed on a substrate holder (12) are sputtered with a DC power source (20)
Implementation Method 2
two or more pulse-wave conversion switches (22, 23) connected in parallel between the DC power source (20) and the first and second sputtering electrodes (18, 19) respectively, each of which converts a DC voltage to a pulse-wave voltage
Implementation Method 3
a film formation chamber (11) that forms a substantially closed space
Implementation Method 4
reactive sputtering apparatus and a film formation method for a composite metal compound film or a mixture film
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An apparatus is provided, comprising: a film formation chamber (11); a substrate holder (12) provided in the film formation chamber and holding a substrate (S) to be formed with a film; a decompressor (13) configured to reduce a pressure in the film formation chamber to a predetermined pressure; a discharge gas introducer (15) configured to introduce a discharge gas into the film formation chamber; two or more sputtering electrodes (18, 19) each provided with a target (T1, T2) to be a film-forming material, the sputtering electrodes facing the substrate as a single substrate; a DC power source (20) configured to supply electric power to the sputtering electrodes; two or more pulse-wave conversion switches (22, 23) connected between the DC power source and the sputtering electrodes, the pulse-wave conversion switches each being configured to convert a DC voltage to be applied to each of the sputtering electrodes to a pulse-wave voltage; a programmable transmitter (24) configured to be programmable with a pulse generation control signal pattern corresponding to the electric power to be supplied to each of the sputtering electrodes, the programmable transmitter being further configured to control each of the pulse-wave conversion switches in accordance with the program; and a pulsed reactive gas introducer (17) configured to control introduction of the reactive gas from the reactive gas introducer to the film formation chamber on the basis of the pulse generation control signal pattern from the electric power controller.