TiN Film Deposition via Pulsed TiCl4 Flow
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Solution Overview
Problem
Current methods for depositing titanium nitride (TiN) films on large semiconductor wafers face challenges in achieving uniformity and low resistivity, particularly at reduced deposition temperatures, which are necessary for integration with other processes like multi-level aluminum or copper metallization, and existing processes are either inefficient or require additional steps.
Innovation Solution
A method involving a batch reactor with a vertically extending reaction chamber that accommodates multiple substrates, where titanium and nitrogen precursors are introduced in temporally separated pulses or continuously, with titanium tetrachloride (TiCl4) and ammonia (NH3) being used as precursors, allowing for deposition at temperatures below 600°C, specifically 450-500°C, to achieve high-quality, uniform TiN films with low resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If deposition temperature is reduced to 400-500°C for integration with multi-level metallization, then compatibility with other processes is improved, but chlorine incorporation increases and resistivity increases substantially
Solution Approach 1:
The patent applies periodic pulsed flow of titanium precursor (TiCl4) into the reaction chamber, alternating with purge cycles. This periodic action allows controlled deposition at lower temperatures (400-500°C) while managing chlorine incorporation through timed purging, thereby achieving both low resistivity and process compatibility
Solution Approach 2:
The patent changes the deposition temperature parameter to the 400-500°C range and adjusts the pulsed precursor flow parameters to optimize film quality. By controlling the duration and frequency of precursor pulses along with temperature parameters, the process achieves low resistivity TiN films compatible with multi-level metallization
2Reliability
If single wafer deposition process with post-deposition anneal is used to reduce resistivity and chlorine content, then film quality is improved, but additional process steps are required and throughput is limited
Solution Approach 1:
The patent performs chlorine removal and resistivity optimization during the deposition process itself through pulsed precursor flow and in-situ purging, rather than requiring post-deposition annealing. This preliminary action eliminates the need for additional process steps while maintaining low resistivity
Solution Approach 2:
The patent combines multiple functions (deposition, chlorine removal, and resistivity optimization) into a single batch reactor process cycle. By merging these operations that were previously separate (deposition followed by anneal), the process improves throughput while maintaining film quality
3Productivity
If batch reactor processing of 200 mm or 300 mm wafers is implemented, then throughput and productivity are improved, but achieving uniformity and low resistivity becomes more difficult
Solution Approach 1:
The patent segments the precursor delivery into temporally separated pulses that are distributed across the batch reactor chamber. This segmentation approach ensures uniform exposure and deposition across large 200 mm or 300 mm wafers processed in batch, achieving both high throughput and excellent uniformity
Solution Approach 2:
The pulsed precursor flow system allows for controlled deposition that can be optimized for uniformity across large wafers. The periodic pulsing provides inherent control that ensures consistent film properties throughout the batch, maintaining manufacturing precision while improving productivity
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 TiN films with uniform thickness and low resistivity on industry-standard wafers, maintaining high quality and throughput while being compatible with other processing steps, achieving resistivity variations of less than 5 μOhm·cm and thickness variations of less than 3 nm across multiple substrates.
Implementation Method 1
chemical vapor depositing titanium nitride on a substrate in a reaction chamber by exposing the substrate to a nitrogen precursor and to a titanium precursor
Data Source
AI summary
Titanium nitride (TiN) films are formed in a batch reactor using titanium chloride (TiCl4) and ammonia (NH3) as precursors. The TiCl4 is flowed into the reactor in temporally separated pulses. The NH3 can also be flowed into the reactor in temporally spaced pulses which alternate with the TiCl4 pulses, or the NH3 can be flowed continuously into the reactor while the TiCl4 is introduced in pulses. The resulting TiN films exhibit low resistivity and good uniformity.