Through-Wafer Interconnect Protection Layer for Semiconductor Reliability

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Solution Overview

Problem

Current methods for producing through-wafer interconnects in semiconductor devices face challenges in ensuring reliable electrical connections and protection of metal layers during subsequent process steps, particularly in removing photoresist residues without damaging the metallization and top-metal layers.

Innovation Solution

A method involving the application of a protection layer, such as silicon dioxide or silicon nitride, immediately after depositing the top-metal to protect the metal layers during cleaning processes, combined with a passivation layer to ensure the reliability of the through-wafer interconnects, which includes forming an opening in the semiconductor substrate, applying a dielectric layer, metallization, and structuring the top-metal and protection layer together.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If cleaning agents are used to remove photoresist residues, then photoresist removal is achieved, but the metallization and top-metal layers are damaged

Engineering Contradiction:

Improvephotoresist residue removalVSAvoidmetal layer integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A protection layer is deposited over the metallization and top-metal layers before the cleaning process. This preliminary protective measure ensures that when aggressive cleaning agents are subsequently applied to remove photoresist residues, the metal layers remain intact and undamaged.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protection layer acts as an intermediary barrier between the cleaning agents and the metal layers. It selectively protects the metal layers from chemical attack while allowing the cleaning process to effectively remove photoresist residues, thus mediating between the conflicting requirements of thorough cleaning and metal layer preservation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the protection layer is applied immediately after top-metal deposition, then metal layer protection is achieved, but process complexity increases

Engineering Contradiction:

Improvemetal layer protectionVSAvoidnumber of process steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protection layer deposition is merged with the existing process flow by applying it immediately after top-metal deposition, before the opening is filled. This timing integration ensures metal layer protection is achieved without requiring separate dedicated process steps, thus minimizing additional process complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 reliability of through-wafer interconnects by effectively protecting the metal layers from cleaning agents, ensuring complete removal of photoresist residues and preventing delamination, thus maintaining the electrical connection integrity.

Implementation Method 1

The selectivity of the chemical attack of the cleaning agent on the substance that is to be removed with respect to its chemical attack on metal should be better for the metal of the protection layer than for the metallization and the top-metal

Methodology Applied

Scientific EffectSelective chemical attack:

Implementation Method 2

A dielectric layer is applied on the semiconductor material in the opening. A metallization is applied, which contacts the contact pad and is separated from the semiconductor material by the dielectric layer. A top-metal is applied on the upper surface and over the edge.

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS8633107B2Method of producing a semiconductor device and semiconductor device having a through-wafer interconnect

Publication Date: 2014.01.21 AUSTRIAMICROSYSTEMS AG

AI summary

A substrate (1) of semiconductor material is provided with a contact pad (7). An opening (9) is formed through the semiconductor material from an upper surface to the contact pad, the opening forming an edge (18) at or near the upper surface. A dielectric layer (10) is applied on the semiconductor material in the opening. A metallization (11) is applied, which contacts the contact pad and is separated from the substrate by the dielectric layer. A top-metal (12) is applied, which contacts the metallization at or near the edge. A protection layer (13) is applied, which covers the top-metal and/or the metallization at least at or near the edge, and a passivation (15) is applied.