Electroplating Voltage Control for Copper Plating Uniformity
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Solution Overview
Problem
The uniformity of copper plating film thickness in semiconductor devices is hindered by the 'terminal effect,' where voltage drop due to seed film resistance results in uneven copper deposition, and attempts to mitigate this with high-resistance materials increase power demands, leading to hardware troubles.
Innovation Solution
Monitoring and adjusting the plating voltage and inorganic component concentrations in the electroplating solution using an automatic analyzer to maintain a preset voltage range, ensuring consistent copper plating film thickness and reducing hardware stress on the electroplating device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resistance material is arranged between anode and cathode to reduce terminal effect, then uniformity of copper plating film thickness is improved, but plating solution resistance increases requiring higher voltage which imposes large load on power source circuit
Solution Approach 1:
The patent changes the chemical composition parameters of the plating solution by adding specific additives (brighteners, levelers, and fillers) to modify the electrical and chemical properties. This allows achieving uniform copper plating film thickness without increasing plating solution resistance or power consumption, as the additives optimize the deposition process at the electrode surface level rather than changing bulk solution resistance
Solution Approach 2:
The patent introduces organic additives (brighteners, levelers, fillers) as intermediary substances that mediate between the electrical field and copper deposition process. These additives adsorb on the cathode surface and modify the deposition behavior, enabling uniform plating without requiring high-resistance materials in the solution path, thus avoiding increased power consumption
2Manufacturing precision
If high-resistance material is arranged between anode and cathode to reduce terminal effect, then uniformity of copper plating film thickness is improved, but hardware margin is reduced causing emergent troubles
Solution Approach 1:
The patent modifies the chemical parameters of the plating solution by incorporating specific additives that optimize copper deposition uniformity. This approach achieves manufacturing precision goals without altering the electrical resistance characteristics that would stress the hardware, thereby maintaining adequate hardware margin and system reliability
Solution Approach 2:
Organic additives serve as intermediaries that facilitate uniform copper plating through surface adsorption and deposition control mechanisms. This eliminates the need for high-resistance materials in the plating solution path, preventing excessive voltage drops and protecting the power source circuit from overloading, thus preserving hardware reliability
3Manufacturing precision
If voltage control is performed to keep current constant, then uniformity of copper plating film thickness is maintained, but terminal effect causes current distribution non-uniformity across wafer surface
Solution Approach 1:
The patent applies different functional additives at different stages of the plating process to address local variations in current distribution. Brighteners, levelers, and fillers create localized effects on the cathode surface that compensate for the terminal effect, ensuring uniform copper deposition even when current density varies across the wafer surface
Solution Approach 2:
Organic additives act as intermediaries between the non-uniform current distribution and the copper deposition process. These substances adsorb preferentially in high-current-density regions, moderating the deposition rate locally and achieving overall uniformity without requiring perfect current distribution across the wafer
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 enhances the uniformity of copper plating films while minimizing hardware issues in electroplating devices by maintaining optimal plating conditions, reducing the need for frequent maintenance and improving semiconductor device quality.
Implementation Method 1
a voltage is applied to the cathode and an anode arranged in such a manner as to face the semiconductor wafer. This causes a current to flow from the semiconductor wafer peripheral part through a seed film (conductive thin film), thereby to grow a copper plating film on the entire surface of the semiconductor wafer
Implementation Method 2
a current to flow from the semiconductor wafer peripheral part through a seed film (conductive thin film)
Data Source
AI summary
An automatic analyzer detects voltage applied across electrodes, and judges whether voltage value falls within set voltage range. When the detected voltage value is lower than minimum value of set voltage range, the analyzer calculates the deficient amount of base solution based on the detected voltage value, controls a valve to supply the deficient amount of base solution, then, performs operation control of the valve so as to keep the prescribed amount of plating solution in plating solution tank, and discharges plating solution. When the detected voltage value is higher than maximum value of set voltage range, the analyzer calculates the excess amount of base solution based on the detected voltage value, controls a valve, and supplies pure water into the tank so that the base solution concentration falls within prescribed range to dilute plating solution, then controls a valve, and discharges plating solution so as to keep prescribed amount.