Pulsed Magnetron Sputtering Timing Offset for Film Quality
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Solution Overview
Problem
Existing pulsed magnetron sputtering methods, particularly high-power impulse magnetron sputtering, face challenges in depositing material layers on insulating substrates or during the growth of thick dielectric layers due to the inability to apply a negative substrate bias, leading to defects, compressive stress, and suboptimal crystallinity.
Innovation Solution
The method involves applying voltage pulses to a synchronizable sputter source with a timed offset relative to a key sputter source, ensuring that the deposited atoms reach the substrate after process gas ions, thereby creating a negative bias that reduces defect concentration, improves crystallinity, and lowers residual compressive stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If voltage pulses are applied to a sputter source for high-power impulse magnetron sputtering, then deposition speed and ionization of sputtered material are improved, but process gas ions arrive at the substrate before material ions, leading to increased process gas incorporation and compressive stress
Solution Approach 1:
The patent applies a preliminary negative substrate bias pulse before the main sputtering voltage pulse. This preliminary action creates a negative potential on the substrate that repels process gas ions (Ar+) from reaching the substrate during the subsequent sputtering pulse, thereby reducing process gas incorporation and compressive stress while maintaining high deposition speed through the main pulse
Solution Approach 2:
The patent employs periodic pulsed sequences with alternating polarity: negative substrate bias pulses followed by positive sputtering pulses. This periodic action allows temporal separation of process gas ion arrival (during negative bias) from material ion arrival (during positive sputtering), solving the timing conflict between achieving high deposition rates and minimizing harmful process gas incorporation
2Manufacturing precision
If a negative substrate bias is applied to accelerate material ions, then film crystallinity and density are improved, but insulating substrates cannot sustain a negative bias potential as their surface potential floats and equilibrates with plasma potential
Solution Approach 1:
The patent applies a preliminary negative substrate bias pulse before the main sputtering pulse. This preliminary action establishes the negative potential on insulating substrates before material deposition begins, allowing the substrate to accumulate charge and maintain the bias potential temporarily. This enables ion acceleration and improved film quality on insulating substrates without requiring continuous bias application
Solution Approach 2:
The patent utilizes the substrate's own charge accumulation capability to maintain the negative bias potential. Insulating substrates naturally accumulate negative charge when exposed to the plasma during the negative bias pulse, creating a self-sustaining potential that continues to repel process gas ions and attract material ions during subsequent pulses without requiring external bias maintenance
3Stability of the object's composition
If process gas ions are accelerated onto the substrate, then adatom mobility is increased, but defect concentration and residual compressive stress in the deposited layer increase
Solution Approach 1:
The patent applies a preliminary negative substrate bias pulse that creates a potential well to trap and accelerate process gas ions onto the substrate surface before material deposition. This preliminary action provides the necessary adatom mobility enhancement without requiring continuous ion bombardment during deposition, thereby reducing defect accumulation and residual stress in the final film
Solution Approach 2:
The patent uses periodic alternating pulses: negative substrate bias pulses for ion acceleration and mobility enhancement, followed by positive sputtering pulses for material deposition. This periodic action separates the ion bombardment phase from the deposition phase, allowing adatom mobility improvement during bias pulses while minimizing defect formation during deposition pulses
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 enables the deposition of high-quality material layers with reduced defects and stress at lower temperatures, suitable for insulating substrates and structured surfaces, enhancing film properties like density and texture.
Implementation Method 1
pulsed magnetron sputtering, in particular high-power impulse magnetron sputtering
Implementation Method 2
voltage pulses are applied with at least one voltage source to the at least one sputter source for generating a plasma from the process gas
Implementation Method 3
pulsed magnetron sputtering
Implementation Method 4
the kinetic energy of the ions can be increased by applying negative potentials on the substrate
Implementation Method 5
a high voltage is applied in short pulses in the μs-range to the sputter source. This results in very high peak current densities and plasma densities
Data Source
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Figure 3A~3D
AI summary
The invention relates to an apparatus (1) and a method for depositing a material layer (101) of a material to be deposited on a substrate (100) by pulsed magnetron sputtering, in particular high-power impulse magnetron sputtering, thereby, a predetermined partial pressure of a process gas is maintained in a deposition chamber (2), the substrate (100) is arranged in the deposition chamber (2) and at least one sputter source (3.1, 3.2, 3.3) is arranged in the deposition chamber (2), the at least one sputter source (3.1, 3.2, 3.3) including a sputter target (4.1, 4.2, 4.3) being made of at least one chemical element of the material to be deposited. Furthermore, voltage pulses are applied with at least one voltage source (5.1, 5.2) to the at least one sputter source (3.1, 3.2, 3.3) for generating a plasma (200) from the process gas in order to sputter atoms, in particular ionised atoms, of target material off the sputter target (4.1, 4.2, 4.3) of the respective one of the at least one sputter source (3.1, 3.2, 3.3) for depositing the respective atoms on the substrate (100) for depositing the material layer on the substrate (100), wherein the voltage pulses applied to a synchronisable one of the at least one sputter source (3.2, 3.3) are applied to the synchronisable one of the at least one sputter source (3.2, 3.3) delayed by an offset in time as compared to the voltage pulses applied to a key one of the at least one sputter source (3.1). Thereby, the offset in time corresponds to a time the atoms, in particular ionised atoms, of the sputter target (4.1) of the key one of the at least one sputter source (3.1) require to reach from the sputter target (4.1) of the key one of the at least one sputter source (3.1) to the substrate (100) after a voltage pulse is applied to the key one of the at least one sputter source (3.1) for generating the plasma (200) from the process gas in order to sputter atoms, in particular ionised atoms, of the target material off the sputter target (4.1) of the key one of the at least one sputter source (3.1). Furthermore, the offset in time is longer than a majority of ions of the process gas require to reach from the plasma (200) in the vicinity of the key one of the at least one sputter source (3.1) to the substrate (100) after a voltage pulse is applied to the key one of the at least one sputter source (3.1) for generating the plasma (200) from the process gas in order to sputter atoms, in particular ionised atoms, of the target material off the sputter target (4.1) of the key one of the at least one sputter source (3.1).