Thick MoSi Contact Capping Through Periodic Precursor Delivery
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Solution Overview
Problem
Existing methods for forming contact capping layers in semiconductor devices result in high contact resistance due to lack of control over thickness and impurities in molybdenum silicide layers, leading to poor connections between frontend-of-the-line and back-end-of-the-line structures.
Innovation Solution
A method involving alternating the delivery of molybdenum and silicon-containing gases with hydrogen in a controlled atmosphere to deposit a contact capping layer, using a soaking process to achieve a continuous thickness with low impurities, thereby reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current MoSi layer deposition techniques are used, then the contact capping layer can be formed, but the thickness and impurities in MoSi layers cannot be controlled, resulting in high contact resistance
Solution Approach 1:
The patent applies periodic action by using pulsed delivery of Mo precursor followed by purging cycles. The Mo precursor is delivered for a first period of time, then halted for a second period of time for purging, and this cycle is repeated. This periodic on-off delivery pattern enables precise control over the amount of Mo deposited, allowing formation of a continuous thick layer with controlled thickness and low impurity content, thereby reducing contact resistance.
Solution Approach 2:
The deposition process is segmented into distinct phases: Mo precursor delivery phase, purging phase, and repeating cycles. By dividing the continuous deposition process into discrete time segments with different gas flows, the patent achieves control over both thickness and impurity levels in the MoSi layer, resolving the contradiction between manufacturability and electrical performance.
2Reliability
If a continuous thick MoSi layer is formed to reduce contact resistance, then better electrical connections are achieved, but current deposition techniques lack control over impurities in the layer
Solution Approach 1:
The periodic delivery and purging of Mo precursor allows the formation of a continuous thick MoSi layer while controlling impurities. During the delivery phase, Mo precursor is supplied to build up the layer thickness. During the purging phase, excess precursor and volatile impurities are removed. Repeating this cycle produces a thick, continuous layer with controlled impurity content, achieving low contact resistance.
Solution Approach 2:
The patent changes the temporal parameters of precursor delivery by using pulsed cycles with specific on-times and off-times. By adjusting the duration of Mo precursor delivery and purging periods, the process controls both the thickness and impurity level of the deposited layer, enabling formation of high-quality thick MoSi contacts.
3Manufacturing precision
If alternating delivery and halting of Mo precursor is used, then precise control over thickness is achieved, but the process complexity increases
Solution Approach 1:
The periodic alternation between Mo precursor delivery and purging, while increasing process steps, provides precise thickness control through repeatable cycles. The regular pattern of delivery-halt-delivery-halt creates a predictable deposition rate, enabling accurate thickness control despite the increased temporal complexity of the process.
Solution Approach 2:
By changing the temporal parameters (delivery time, purging time, cycle repetition) of the deposition process, the patent achieves precise thickness control. The systematic variation of these parameters allows tuning of the final layer thickness while maintaining a manageable process structure through automated cycle control.
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
The method provides precise control over the thickness and quality of the contact capping layer, resulting in improved electrical connections and reduced overall device resistance.
Implementation Method 1
depositing a contact capping layer over a surface of a contact structure, the contact capping layer deposition process comprising flowing hydrogen (H2) and a silicon containing gas into a processing chamber for a first period of time, and delivering a molybdenum (Mo) precursor for a second period of time
Data Source
AI summary
A method includes depositing a contact capping layer over a surface of a contact structure, the contact capping layer deposition process comprising flowing hydrogen (H2) and a silicon containing gas into a processing chamber, and delivering a molybdenum (Mo) precursor for a first period of time and halting delivering of the Mo precursor for a second period of time while flowing the hydrogen (H2) and the silicon containing gas, and repeating delivering the Mo precursor and halting delivering the Mo precursor one or more times while flowing the hydrogen (H2) and the silicon containing gas.