Silicon Wafer BMD Control for Slip and Warpage
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Solution Overview
Problem
Conventional silicon wafer manufacturing methods fail to effectively suppress slip dislocation and warpage, particularly in larger diameter wafers, due to inadequate control of Bulk Micro Defect (BMD) concentration and size, leading to weakened wafer strength and reduced semiconductor device yield.
Innovation Solution
A method that controls BMDs with sizes of 200 µm or more at a concentration of 2 x 10^9/cm^3 or less immediately under the Denuded Zone (DZ) layer and 10 nm to 50 nm at a density of 1 x 10^12/cm^3 or more at a depth of 50 µm or more, using specific heat treatment processes to manage stress and dislocation, and optimizing BMD shape distribution to minimize slip and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature annealing is performed to form a Denuded Zone layer and eliminate grown-in defects, then crystal defect reduction is achieved, but oxygen outward diffusion occurs causing low oxygen concentration in the DZ layer which reduces wafer strength and enables slip dislocation extension
Solution Approach 1:
The patent applies parameter changes by precisely controlling heat treatment temperature (900-1100°C), nitrogen concentration (1×10^14 to 1×10^16 atoms/cm³), and treatment time (30-180 minutes) to achieve optimal balance between DZ layer formation and oxygen retention. This controlled parameter adjustment prevents excessive oxygen diffusion while maintaining defect elimination effectiveness.
Solution Approach 2:
The patent introduces nitrogen as an intermediary element that forms BMDs with specific size distribution. These nitrogen-containing BMDs act as gettering centers for metal impurities while the controlled nitrogen concentration prevents excessive oxygen outward diffusion, thereby maintaining DZ layer integrity and wafer strength simultaneously.
2Manufacturing precision
If high-temperature annealing is performed to form BMDs with nitrogen cores, then grown-in defects on the surface are reduced, but the DZ layer formed has extremely low oxygen concentration which causes prohibitive power of dislocation defect extension
Solution Approach 1:
The patent changes the parameter of BMD size distribution by controlling nitrogen concentration and heat treatment conditions to create a dual-mode BMD structure: small BMDs (10-50 nm) at high concentration for surface defect reduction, and controlled larger BMDs deeper in the substrate. This parameter optimization prevents dislocation extension while maintaining surface quality.
Solution Approach 2:
The patent applies local quality by creating different BMD concentration and size distributions at different depths and locations within the wafer. The DZ layer has specific oxygen and nitrogen concentration profiles that differ from the bulk, with nitrogen-enriched regions providing localized gettering while maintaining overall structural integrity and preventing dislocation propagation.
3Strength
If BMDs are generated at high concentration to prevent slip dislocation, then slip suppression is improved, but warpage occurs in larger diameter wafers due to stress distribution
Solution Approach 1:
The patent applies local quality by creating a depth-dependent BMD size distribution: small BMDs (10-50 nm) concentrated in the upper region (0-20 µm depth) to suppress slip dislocation, and controlled larger BMDs in deeper regions. This localized differentiation addresses slip prevention needs at the surface while managing stress distribution deeper in the wafer to minimize warpage in large-diameter substrates.
Solution Approach 2:
The patent changes the parameter of BMD size distribution with depth by controlling nitrogen concentration gradients and heat treatment parameters. The nitrogen concentration (1×10^14 to 1×10^16 atoms/cm³) and treatment time (30-180 minutes at 900-1100°C) are optimized to create the desired BMD size and concentration profile that simultaneously suppresses slip and minimizes warpage.
4Productivity
If a silicon wafer increases in diameter to accommodate higher integration density, then manufacturing capacity is improved, but slip dislocation and warpage become more problematic
Solution Approach 1:
The patent applies local quality by creating spatially varying BMD characteristics within large-diameter wafers. The nitrogen concentration and BMD size distribution are optimized for different radial and depth positions, with higher nitrogen concentration and smaller BMDs near the surface for slip suppression, and controlled distributions in bulk regions for warpage management, enabling reliable manufacturing of large-diameter high-density wafers.
Solution Approach 2:
The patent changes multiple parameters including nitrogen concentration (1×10^14 to 1×10^16 atoms/cm³), heat treatment temperature (900-1100°C), and treatment time (30-180 minutes) to achieve optimal BMD size and distribution. These parameter optimizations enable large-diameter wafers to maintain high integration density while controlling slip dislocation and warpage through precisely engineered defect structures.
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 significantly reduces occurrences of slip dislocation and warpage, maintaining wafer strength while enabling the formation of a high-quality DZ layer, suitable for large-scale semiconductor device manufacturing.
Implementation Method 1
the DZ layer formed on the upper and lower surfaces of the silicon wafer by the high-temperature annealing process has an oxygen concentration which is extremely low because of outward diffusion of oxygen during heat treatment
Implementation Method 2
a rapid heat raising/falling temperature heat treatment is performed to a substrate cut out of a silicon single-crystal ingot in an atmosphere of a gas mixture of a nitrogen gas or an inert gas or an ammonia gas and an inert gas at a temperature of 500°C or more to 1200°C or less for 1 minute or more to 600 minutes or less to form oxygen deposition cores
Implementation Method 3
a method which performs high-temperature annealing to the silicon wafer to induce the BMD in the silicon wafer to form an Intrinsic Gettering layer, eliminates a grown-in defect being present on the surface of the silicon wafer
Data Source
AI summary
To provide a silicon wafer which can suppress both occurrences of slip dislocation and warpage in device manufacturing processes and a method of manufacturing the same. A silicon wafer according to the present invention is a silicon wafer having BMDs each having an octahedral shape. BMDs located at a position shallower than the silicon wafer surface by a depth of 20 µm or more and having a diagonal length of 200 nm or more have a concentration of 2 x 109/cm3 or less, and a BMD located at a position having a depth 50 µm or more and has a diagonal length of 10 nm or more to 50 nm or less has a concentration of 1 x 1012/cm3 or more.