Semiconductor Bond Pad Surface Protective Film Structure
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Solution Overview
Problem
The use of halogen-free resin members in semiconductor devices leads to water permeation through the resin, causing chemical reactions with exposed titanium nitride films at the side surfaces of openings, resulting in increased volume and stress, which can crack the surface protective film and lead to corrosion of the aluminum film, thereby degrading the reliability of the semiconductor device.
Innovation Solution
The semiconductor device is designed with a configuration where the second opening in the surface protective film is included within the first opening, ensuring the side surface of the antireflection film is covered, preventing water from coming into direct contact with the titanium nitride film, and using a two-layer surface protective film structure to manage stress and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer surface protective film with one opening is used, then the structure is simple and manufacturing is easy, but water permeates through the opening and causes chemical reactions with the exposed antireflection film, leading to cracking and corrosion
Solution Approach 1:
The surface protective film is divided into two separate layers (first surface protective film and second surface protective film), each serving specific functions. The first film provides initial protection while the second film prevents water permeation and chemical reactions, thereby resolving the contradiction between structural simplicity and device reliability.
Solution Approach 2:
The second surface protective film is formed to cover and embed the first surface protective film and the opening. This nested structure allows the second film to protect the underlying layers from water permeation while maintaining a compact overall design, addressing both simplicity and reliability requirements.
2Ease of operation
If the opening in the surface protective film is made larger to expose more pad area, then bonding wire connection is improved, but the side surface of the antireflection film becomes more exposed, increasing the risk of water reaction and cracking
Solution Approach 1:
The solution moves from a two-dimensional planar protection approach to a three-dimensional layered protection approach. By forming the second surface protective film that wraps around and covers the side surfaces of the opening and antireflection film, the patent provides protection in the vertical dimension while maintaining adequate horizontal pad exposure for bonding wire connection.
3Adaptability or versatility
If halogen-free resin members are used to seal the semiconductor chip, then environmental compliance is improved, but water permeation through the resin causes chemical reactions with the antireflection film, leading to volume expansion and cracking
Solution Approach 1:
The second surface protective film is formed in advance, before the halogen-free resin member is applied, to create a protective barrier against water permeation. This preliminary protective action prevents the harmful chemical reactions that would otherwise occur when water penetrates through the halogen-free resin, thereby maintaining both environmental compliance and device reliability.
Solution Approach 2:
The second surface protective film acts as an intermediary barrier between the external environment (including water that may permeate through the halogen-free resin) and the sensitive antireflection film. This intermediary layer prevents direct contact between water and the antireflection film, eliminating the harmful chemical reactions while allowing the use of environmentally compliant halogen-free resin materials.
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 configuration effectively suppresses the formation of titanium oxide and subsequent cracking, maintaining the integrity of the surface protective film and preventing corrosion of the aluminum film, thereby enhancing the reliability of the semiconductor device even when using halogen-free resin members.
Implementation Method 1
water permeation through the resin
Implementation Method 2
chemical reactions with exposed titanium nitride films at the side surfaces of openings
Implementation Method 3
increased volume and stress, which can crack the surface protective film
Data Source
AI summary
To provide: a technique capable of suppressing a titanium nitride film that is exposed at the side surface of an opening from turning into a titanium oxide film even when water permeates the opening over a pad from outside a semiconductor device and thus improving the reliability of the semiconductor device; and a technique capable of suppressing a crack from occurring in a surface protective film of a pad and improving the reliability of a semiconductor device. An opening is formed so that the diameter of the opening is smaller than the diameter of another opening and the opening is included in the other opening. Due to this, it is possible to cover the side surface of an antireflection film that is exposed at the side surface of the other opening with a surface protective film in which the opening is formed. As a result of this, it is possible to form a pad without exposing the side surface of the antireflection film.