Silicon-Filled Opening Void Reduction via Amorphous Deposition and Annealing
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Solution Overview
Problem
Semiconductor devices often form voids or seams in silicon-filled openings due to non-uniform deposition processes, which can adversely impact electronic device performance.
Innovation Solution
A method involving the deposition of an amorphous silicon film into substrate openings, followed by exposure to a silicon mobility inhibitor and subsequent annealing, which reduces or eliminates voids while maintaining the surface smoothness and converting the amorphous silicon to a more crystalline form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon is deposited to fill the opening from the sides and bottom, then the opening can be completely filled, but non-uniform growth causes voids and seams to form in the interior
Solution Approach 1:
The patent changes the deposition temperature parameter to below 550°C to deposit amorphous silicon instead of crystalline silicon. This parameter change allows for more uniform deposition behavior and reduces the formation of voids and seams during the filling process, as amorphous silicon exhibits different growth characteristics compared to crystalline silicon.
Solution Approach 2:
The patent utilizes the phase transition of silicon from amorphous to crystalline state through controlled annealing. The silicon is first deposited in amorphous phase at low temperature to ensure uniform filling, then subsequently annealed to convert it to the desired crystalline phase, thereby avoiding void formation during deposition while achieving the required material properties.
2Productivity
If the top of the opening closes up first due to higher deposition rate, then filling is completed faster, but voids are trapped in the interior
Solution Approach 1:
By changing the deposition temperature to below 550°C, the patent modifies the deposition kinetics to produce amorphous silicon with more uniform growth rates throughout the opening. This prevents the top surface from closing up prematurely and trapping voids, while still maintaining efficient filling speeds.
3Manufacturing precision
If amorphous silicon is deposited at low temperature, then uniform filling is achieved, but the silicon must be subsequently annealed to convert to polysilicon
Solution Approach 1:
The patent intentionally deposits silicon in the amorphous phase at low temperature to achieve uniform filling, then employs a controlled annealing process to transition the material to the desired polysilicon phase. This two-step approach separates the uniformity achievement (deposition) from the phase requirement (annealing), optimizing each step independently.
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 effectively reduces or eliminates voids in silicon-filled openings, ensuring a smooth surface and crystallization of the silicon, making the silicon fill suitable for integrated circuit structures without causing surface roughening.
Implementation Method 1
The deposited amorphous silicon film is exposed to an oxidizing gas, a nitriding gas, or an n-type dopant gas at a temperature of about 575° C. or below
Implementation Method 2
The deposited amorphous silicon film is exposed to an oxidizing gas, a nitriding gas, or an n-type dopant gas at a temperature of about 575° C. or below
Implementation Method 3
The substrate is subsequently heated to an anneal temperature. The substrate is then maintained at the anneal temperature to crystallize the amorphous silicon film in the trench. This anneal may convert the amorphous silicon film to a polysilicon film
Implementation Method 4
The substrate is then maintained at the anneal temperature to crystallize the amorphous silicon film in the trench
Data Source
AI summary
In some embodiments, silicon-filled openings are formed having no or a low occurrence of voids in the silicon fill, while maintaining a smooth exposed silicon surface. In some embodiments, an opening in a substrate may be filled with silicon, such as amorphous silicon. The deposited silicon may have interior voids. This deposited silicon is then exposed to a silicon mobility inhibitor, such as an oxygen-containing species and/or a semiconductor dopant. The deposited silicon fill is subsequently annealed. After the anneal, the voids may be reduced in size and, in some embodiments, this reduction in size may occur to such an extent that the voids are eliminated.