DC Voltage Control for Ion Energy Distribution in Etching
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Solution Overview
Problem
The existing substrate processing apparatuses face challenges in achieving good processing controllability during etching due to the strong anisotropy or isotropy in ion energy distribution caused by the LF high frequency voltage, which affects the formation of desired shapes in semiconductor wafers.
Innovation Solution
A substrate processing apparatus and method that includes a DC voltage applying unit to generate a rectangle-shaped wave on the mounting table, allowing for independent control of connection/disconnection with the HF and LF high frequency power supplies, enabling adjustment of ion energy distribution and controlling the intensity of anisotropy and isotropy in the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LF high frequency voltage is applied to generate bias voltage in the susceptor, then ion energy distribution has both low and high energy peaks, but processing controllability deteriorates due to strong anisotropy or isotropy in etching
Solution Approach 1:
The patent segments the single bias voltage generation function into two independent voltage application systems: one for generating the bias voltage (LF high frequency power supply) and another for controlling ion energy distribution (DC voltage power supply). This segmentation allows independent optimization of each function, resolving the contradiction between achieving desired ion energy distribution and maintaining processing controllability.
Solution Approach 2:
The DC voltage power supply acts as an intermediary component that mediates between the bias voltage generation and the etching process. By introducing this intermediate voltage control mechanism, the system can adjust ion energy distribution without directly affecting the bias voltage, thereby maintaining processing controllability while achieving desired etching characteristics.
2Quantity of substance
If LF high frequency voltage is used for bias voltage generation, then ion energy distribution becomes fixed with specific anisotropy/isotropy, but adaptability in etching process deteriorates
Solution Approach 1:
The patent introduces dynamic control capability by adding the DC voltage power supply that can independently adjust its output voltage. This transforms the static ion energy distribution (determined solely by LF high frequency voltage) into a dynamic system where ion energy can be continuously adjusted by varying the DC voltage, thereby achieving adaptability in etching processes while maintaining the bias voltage generation function.
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 allows for improved processing controllability by shaping the ion energy distribution, ensuring precise etching results by varying the ratio of outputs from the HF and DC voltage applying units, thereby optimizing the etching process.
Implementation Method 1
A processing gas introduced into the processing chamber is excited into plasma by applying the HF high frequency voltage
Implementation Method 2
A bias voltage is generated in the susceptor by applying the LF high frequency voltage. In this case, a self bias is generated in the susceptor
Implementation Method 3
When an electric potential of the susceptor is time-averaged, the electric potential has a negative value. Accordingly, ions are attracted to the susceptor by the electric potential difference
Data Source
AI summary
A connection control method in a substrate processing apparatus is provided. The substrate processing apparatus comprises: a depressurized processing room; a susceptor that is provided in the processing room and configured to mount a wafer thereon; a HF high frequency power supply configured to apply a high frequency voltage for plasma generation to the susceptor; a LF high frequency power supply configured to apply a high frequency voltage for a bias voltage generation to the susceptor; and a DC voltage applying unit configured to apply a DC voltage of a rectangle-shaped wave to the susceptor, capable of improving a processing controllability in an etching process. The connection control method comprises controlling connection or disconnection between the susceptor and the LF high frequency power supply and connection or disconnection between the susceptor and the DC voltage applying unit when plasma is generated in the processing room.