Electroless Pad Plating With Backmetal Protection Against Oxidation
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Solution Overview
Problem
Current semiconductor device manufacturing processes face challenges in effectively protecting semiconductor substrates during electroless metal plating, particularly in preventing oxidation and phase shifts of metal layers, which can affect the integrity and performance of the devices.
Innovation Solution
The method involves providing a semiconductor substrate with a backmetal layer and electrolessly depositing a metal layer on a pad, followed by baking in a nitrogen atmosphere at controlled temperatures to prevent oxidation and ensure proper deposition, and then singulating the substrate into semiconductor die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electroless plating is performed without protective measures, then the plating process is simple and fast, but oxidation and phase shifts occur in the metal layers
Solution Approach 1:
A protective coating is applied to the backmetal layer before the electroless plating process begins. This preliminary protective measure prevents oxidation during subsequent high-temperature baking steps while allowing the plating chemistry to proceed normally on the exposed pad surfaces.
Solution Approach 2:
The process utilizes a controlled atmosphere during electroless plating and baking, where the protective coating creates a localized inert environment on the backmetal layer, preventing oxidation without requiring the entire chamber to be filled with inert gas.
2Reliability
If high temperature baking is performed to prevent oxidation, then metal layer protection is improved, but phase shifts and thermal damage may occur
Solution Approach 1:
The process optimizes the baking temperature profile and duration based on the specific metal layer composition and thickness. By carefully controlling these parameters, sufficient oxidation protection is achieved while minimizing thermal exposure that could cause phase shifts or thermal damage to the semiconductor substrate.
Solution Approach 2:
The protective coating is applied before baking, creating a shield that allows higher temperature processing to be used for oxidation prevention without directly exposing the metal layers to harsh thermal conditions that would cause phase shifts.
3Manufacturing precision
If tape is attached over backmetal layer during plating, then selective deposition is achieved, but additional process steps are required
Solution Approach 1:
The tape is pre-positioned on the backmetal layer before the electroless plating process begins. This preliminary placement ensures that only the intended pad areas are exposed to the plating chemistry, achieving precise selective deposition while streamlining the overall process flow.
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 protection of semiconductor substrates by reducing oxidation and phase shifts, improving the integrity and performance of the metal layers, and facilitating efficient processing into multiple semiconductor die.
Implementation Method 1
electroless depositing a metal layer on a pad included on the first largest planar surface
Implementation Method 2
baking the semiconductor substrate in a nitrogen atmosphere at controlled temperatures to prevent oxidation
Data Source
AI summary
Implementations of a method of electroless deposition may include providing a semiconductor substrate including a first largest planar surface and a second largest planar surface; forming a backmetal layer on the second largest planar surface; attaching a tape over the backmetal layer; and electroless depositing a metal layer on a pad included on the first largest planar surface. The method may include, after electroless depositing, removing the tape; and after removing the tape, baking the semiconductor substrate.