Direct Bonding Semiconductor Substrates via Plasma Surface Treatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing direct bonding techniques for hybrid substrates in electronics, optics, and optoelectronics face challenges in achieving sufficient bond quality without macroscopic defects, such as bubbles, especially when high heat conduction and electrical conduction between substrates are required, and when substrates have different crystal orientations or are elastically stressed.
Innovation Solution
A method involving a heat treatment of substrate surfaces at 900° C. to 1200° C. in a hydrogen or argon atmosphere to eliminate native oxide and passivate surfaces, followed by direct bonding without an intermediate layer, which reduces surface roughness and minimizes contamination, allowing for high-quality bonding even with thin or no insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct bonding is performed without an intermediate layer, then heat conduction and electrical conduction between substrates are improved, but bond quality deteriorates due to macroscopic defects such as bubbles
Solution Approach 1:
The patent applies preliminary surface treatment by exposing substrate surfaces to a hydrogen or oxygen plasma atmosphere before bonding. This preliminary action eliminates native oxide layers and passivates surface contaminants, ensuring clean bonding surfaces that prevent bubble formation while allowing direct bonding without intermediate layers, thus maintaining both high heat conduction and bond quality
Solution Approach 2:
The patent uses a hydrogen or oxygen plasma atmosphere as an inert/controlled environment during surface treatment. This controlled atmosphere prevents oxidation and contamination of bonding surfaces, enabling direct bonding without intermediate layers while avoiding macroscopic defects, thereby achieving both improved heat conduction and reliable bonding
2Reliability
If an intermediate layer is formed between substrates, then bond quality is improved by reducing defects, but heat conduction and electrical conduction are reduced
Solution Approach 1:
The patent extracts/removes the intermediate bonding layer entirely by performing direct bonding after plasma surface treatment. By eliminating the intermediate layer through preliminary surface preparation, the invention achieves both high bond quality (without defects) and improved heat/electrical conduction, as the directly bonded substrates maintain intimate thermal and electrical contact
3Object-affected harmful factors
If substrate surfaces are cleaned by traditional methods, then contamination is reduced, but surface roughness increases
Solution Approach 1:
The patent replaces traditional mechanical/chemical cleaning methods with plasma surface treatment. The plasma atmosphere chemically etches and passivates surfaces without mechanical contact, effectively removing contaminants while maintaining or even improving surface smoothness, thus achieving both low contamination and low surface roughness
Solution Approach 2:
The patent changes the surface treatment parameter from mechanical/chemical cleaning to plasma exposure. By controlling plasma parameters (hydrogen or oxygen atmosphere, exposure time, power), the invention achieves effective contamination removal while maintaining surface smoothness, avoiding the roughening effect of traditional cleaning methods
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 method achieves high-quality direct bonding with low surface roughness and minimal defects, enhancing bond strength and reducing reactivity, making it suitable for applications requiring improved heat and electrical conduction, and is easier to implement than traditional methods.
Implementation Method 1
exposing at least the surface of the first substrate to a temperature from about 900° C. to about 1200° C. in a hydrogen or argon atmosphere
Implementation Method 2
passivate surfaces
Implementation Method 3
direct bonding of two substrates, i.e. molecular bonding without any intermediate layer
Data Source
AI summary
The invention provides methods of direct bonding substrates at least one of which includes a layer of semiconductor material that extends over its front face or in the proximity thereof. The provided methods include, prior to bonding, subjecting the bonding face of at least one substrate comprising a semiconductor material to selected heat treatment at a selected temperature and in a selected gaseous atmosphere. The bonded substrates are useful for electronic, optic, or optoelectronic applications.