Silicon Epitaxy Denuding Process for BMD-Free BCD Chips
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods of manufacturing semiconductor integrated circuit chips in BCD technology face challenges such as the formation of bulk microdefects (BMDs) due to interstitial oxygen, leading to dislocations and current leakages, particularly in bipolar-CMOS-DMOS (BCD) chips.
Innovation Solution
A denuding thermal treatment at temperatures above 1,000°C is applied to the substrate before or after forming an epitaxial layer, diffusing interstitial oxygen out of the upper layer to create a denuded zone, thereby preventing BMD formation and reducing stress-induced dislocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate with interstitial oxygen is used for manufacturing BCD chips, then the substrate is readily available and cost-effective, but bulk microdefects form during thermal processing causing dislocations and current leakages
Solution Approach 1:
A denuding thermal treatment is applied to the substrate before any other thermal processing steps (such as epitaxy or device fabrication) to remove interstitial oxygen from the upper layer. This preliminary action creates a denuded zone that prevents subsequent formation of bulk microdefects during later thermal processing, thereby eliminating the root cause of dislocations and current leakages while allowing the use of cost-effective substrates with initial interstitial oxygen content
Solution Approach 2:
The interstitial oxygen present in the substrate, which normally causes harmful bulk microdefects, is converted into a beneficial outcome by using controlled thermal diffusion to migrate the oxygen deeper into the substrate or toward the surface where it can be removed. This transforms the harmful interstitial oxygen into a controlled process parameter that, when properly managed, creates a denuded zone free of defects in the critical upper layer where devices are fabricated
2Reliability
If high temperature thermal treatment is applied to remove interstitial oxygen, then BMD formation is prevented, but processing time and energy consumption increase
Solution Approach 1:
The denuding thermal treatment is performed at high temperatures (typically above 900°C) but for relatively short durations (minutes to a few hours), optimizing the balance between oxygen removal efficiency and processing time. By precisely controlling temperature, time, and atmospheric conditions, the process achieves effective denuding without excessive energy consumption or time loss, making it compatible with existing semiconductor manufacturing cycles
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
The method effectively prevents BMD formation in the upper layer, reducing dislocations and enhancing the reliability and performance of BCD chips by maintaining a low interstitial oxygen concentration and BMD density in the critical upper portion of the substrate.
Implementation Method 1
applying to the substrate a denuding thermal treatment, at a temperature higher than or equal to 1,000° C. for several hours... diffusing interstitial oxygen out of the upper layer
Implementation Method 2
forming by epitaxy, on top of and in contact with the upper surface of the substrate, a doped single-crystal silicon layer
Data Source
AI summary
A substrate made of doped single-crystal silicon has an upper surface. A doped single-crystal silicon layer is formed by epitaxy on top of and in contact with the upper surface of the substrate. Either before or after forming the doped single-crystal silicon layer, and before any other thermal treatment step at a temperature in the range from 600° C. to 900° C., a denuding thermal treatment is applied to the substrate for several hours. This denuding thermal treatment is at a temperature higher than or equal to 1,000° C.