Bipolar Electrostatic Chuck Switching for Faster Dechuck
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor manufacturing, electrostatic chucks used for substrate clamping in vacuum systems experience prolonged dechuck times due to electrostatic charge retention, which reduces productivity by increasing the residence time in the process module.
Innovation Solution
A method involving a bipolar electrostatic chuck (ESC) with alternating bipolar modes of operation and reduced cooling gas pressure during polarity switches to maintain substrate positioning, combined with an inert plasma for charge removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If electrostatic charge retention is used to maintain substrate clamping, then substrate positioning stability is improved, but dechuck time increases
Solution Approach 1:
The patent applies periodic switching of the bipolar electrostatic chuck between positive and negative voltage modes during the plasma etching process. This periodic action continuously redistributes and dissipates electrostatic charge on the substrate surface, preventing charge accumulation that would otherwise extend dechuck time, while maintaining adequate clamping force throughout the process.
2Stability of the object's composition
If cooling gas pressure is increased to maintain substrate clamping during polarity switches, then substrate positioning is maintained, but substrate movement occurs
Solution Approach 1:
The patent dynamically adjusts the cooling gas pressure in response to bipolar mode switching. When the ESC switches polarity, the clamping force temporarily fluctuates; the system responds by modulating cooling gas pressure to compensate, maintaining stable substrate positioning without causing gas-induced substrate movement that would occur with static high pressure.
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
Substantial reductions in dechuck times are achieved, particularly at high temperatures, enhancing productivity by minimizing substrate residence time.
Implementation Method 1
Electrostatic attraction between the ESC and the substrate allows pressurization of cavities or channels between the substrate and the surface of the ESC
Implementation Method 2
pressurization of cavities or channels between the substrate and the surface of the ESC with an inert gas such as He at a sufficiently high pressure to facilitate good thermal conduction between the substrate and the thermally controlled ESC
Implementation Method 3
plasma etching the semiconductor substrate
Data Source
Figure 1
Figure 2
Figure 3
AI summary
According to the invention there is provided a method of plasma etching a semiconductor substrate comprising the steps of: positioning a semiconductor substrate on a substrate support within a chamber so that an upper surface of the semiconductor substrate can be exposed to the plasma etching and a lower surface of the semiconductor substrate is supported by the substrate support, wherein the substrate support comprises a bipolar electrostatic chuck ("ESC") and a cooling gas system for supplying a cooling gas to the lower surface at an associated pressure, and wherein the ESC comprises at least a first electrode and a second electrode; plasma etching the semiconductor substrate; and removing the semiconductor substrate from the substrate support after the plasma etching step is completed; in which, during the plasma etching step: a cooling gas is supplied to the lower surface of the semiconductor substrate at an associated pressure; the ESC is switched between a first bipolar mode of operation in which a positive voltage is applied to the first electrode and a negative voltage is applied to the second electrode, and a second bipolar mode of operation in which a negative voltage is applied to the first electrode and a positive voltage is applied to the second electrode; and the pressure of the cooling gas is reduced when the ESC is switched between the first and second bipolar modes of operation with respect to the pressure at other times during the plasma etching step so that the semiconductor substrate remains positioned on the substrate support.