Silicon Seed Layer Cycling for Low-Chlorine Film Growth
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Solution Overview
Problem
Existing methods for forming a silicon film on a substrate in semiconductor manufacturing often result in films with suboptimal characteristics, such as high chlorine concentration and uncontrollable thickness.
Innovation Solution
A method involving alternating cycles of supplying halogen-containing and hydrogen gases to the substrate at different pressures to form a silicon seed layer, followed by a silicon film, where the hydrogen gas supply pressure is higher than the halogen-containing gas supply pressure, promoting desorption of chlorine and controlling the seed layer's thickness and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon seed layer is formed by supplying halogen-containing gas to the substrate, then a silicon film can be deposited on the substrate, but the film contains high chlorine concentration which deteriorates film characteristics
Solution Approach 1:
The patent applies periodic action by alternating between halogen-containing gas supply and hydrogen gas supply in cyclic manner. The halogen-containing gas supplies silicon for seed layer formation, followed by hydrogen gas that removes chlorine through desorption. This periodic cycling continues for multiple cycles (e.g., 1-10 cycles) to progressively reduce chlorine concentration while maintaining silicon deposition, thereby resolving the contradiction between achieving sufficient silicon film deposition and minimizing harmful chlorine content.
Solution Approach 2:
The patent converts the harmful effect of halogen-containing gas (chlorine incorporation into film) into a beneficial process by introducing hydrogen gas that promotes chlorine desorption. The chlorine that would otherwise remain trapped and harm film characteristics is instead actively removed through the hydrogen treatment step. This transforms the harmful chlorine incorporation into a controllable process where chlorine is temporarily introduced then systematically removed, improving final film quality.
2Productivity
If halogen-containing gas is supplied at high pressure to increase deposition rate, then productivity improves, but chlorine concentration in the film increases which worsens film characteristics
Solution Approach 1:
The patent uses periodic action to decouple deposition rate from chlorine concentration. During the halogen-containing gas supply phase, high pressure can be used to maximize silicon deposition rate. Then during the hydrogen gas supply phase, chlorine is removed through desorption. This periodic separation allows high productivity during deposition phases while ensuring low chlorine concentration after hydrogen treatment phases, resolving the contradiction between fast deposition and low chlorine content.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting pressure conditions between different gas supply phases. High pressure is applied during halogen-containing gas supply to enhance deposition rate, then pressure is modified during hydrogen gas supply to optimize chlorine desorption. This dynamic parameter adjustment allows the system to achieve high productivity when needed while maintaining low chlorine concentration through subsequent parameter changes, resolving the contradiction between deposition rate and chlorine content.
3Reliability
If the thickness of the silicon seed layer is increased to improve film quality, then film characteristics improve, but the thickness becomes uncontrollable
Solution Approach 1:
The patent applies periodic action with fixed cycle durations for each gas supply phase. Each cycle consists of a predetermined time period for halogen-containing gas supply followed by a predetermined time period for hydrogen gas supply. By controlling the number of cycles and the duration of each phase, the seed layer thickness becomes precisely controllable. The repetitive nature of the cycles ensures uniform growth rate, improving thickness uniformity across the substrate while maintaining controllable total thickness through cycle number adjustment.
Solution Approach 2:
The patent implements feedback control by monitoring film formation progress and adjusting the number of cycles or phase durations accordingly. The hydrogen gas supply phase acts as a feedback mechanism that removes excess chlorine and allows real-time assessment of film quality. Based on this feedback, the process can be adjusted to achieve the desired thickness and quality without overshooting, thereby improving both film quality and thickness controllability simultaneously.
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 results in a silicon seed layer with low chlorine concentration and controlled thickness, enhancing the film's characteristics and quality.
Implementation Method 1
supplying a second gas containing hydrogen to the substrate... promoting desorption of chlorine
Implementation Method 2
supplying a first gas containing halogen and silicon to the substrate... forming a silicon seed layer
Data Source
AI summary
There is provided a technique that includes: (a) forming a silicon seed layer on a substrate by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a1) supplying a first gas containing halogen and silicon to the substrate; and (a2) supplying a second gas containing hydrogen to the substrate; and (b) forming a film containing silicon on the silicon seed layer by supplying a third gas containing silicon to the substrate, wherein a pressure of a space in which the substrate is located in (a2) is set higher than a pressure of the space in which the substrate is located in (a1).