Semiconductor Substrate Gettering via Carbon-Oxygen Precipitates
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Solution Overview
Problem
The gettering effect in semiconductor substrates for solid-state image sensing devices is limited by the upper temperature constraint after carbon ion implantation, leading to increased production costs and particle defects, particularly in the device production step.
Innovation Solution
Incorporating solid-soluted carbon into the silicon lattice to form carbon-oxygen based precipitates, which act as a high-density gettering sink beneath the buried photodiode, utilizing heat treatment to separate these precipitates and enhance the gettering effect without increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon ion implantation is used to form gettering sinks, then white defects are reduced, but the treating temperature must be limited which increases production cost and time
Solution Approach 1:
The patent changes the concentration parameter of carbon atoms in the silicon substrate from the conventional 1x10^16 to 1x10^17 atoms/cm³. This parameter change allows the gettering sinks to remain effective at higher treating temperatures (900-1100°C), thereby resolving the contradiction between defect reduction and production efficiency.
2Object-affected harmful factors
If conventional gettering methods are used, then heavy metal contamination is avoided, but multi-stage heat treatment is required which increases production cost
Solution Approach 1:
The patent performs preliminary action by incorporating carbon atoms into the silicon substrate before device fabrication. This preliminary carbon incorporation creates gettering sinks that are active during subsequent heat treatment steps, eliminating the need for separate multi-stage heat treatment processes required by conventional intrinsic gettering methods.
Solution Approach 2:
The patent merges the gettering sink formation process with the device fabrication heat treatment steps. By incorporating carbon atoms beforehand, the gettering function is integrated into the existing thermal processing steps, combining multiple functions into a single process flow and reducing production complexity.
3Object-affected harmful factors
If extrinsic gettering method is used with backside damage, then heavy metal contamination is avoided, but particles are generated from back side causing defective devices
Solution Approach 1:
The patent extracts the gettering function from the back side of the substrate (where it causes particle generation) and relocates it to the front surface region where carbon atoms are incorporated. This extraction eliminates the source of particles while maintaining the heavy metal contamination prevention function.
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 effectively suppresses heavy metal diffusion and reduces defects, resulting in high-quality solid-state image sensing devices with improved electric characteristics at a lower production cost.
Implementation Method 1
a silicon substrate containing carbon at a solid-soluted state
Implementation Method 2
carbon-oxygen based precipitates having a high gettering ability
Implementation Method 3
form an epitaxial layer of silicon on such a surface for the purpose of reducing white defects
Implementation Method 4
utilizing the heat treatment step in the production step of mounting a device on the semiconductor substrate
Implementation Method 5
form an epitaxial layer of silicon on such a surface
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3
AI summary
There is provided a semiconductor substrate for solid-state image sensing device in which the production cost is lower than that of a gettering method through a carbon ion implantation and problems such as occurrence of particles at a device production step and the like are solved. Silicon substrate contains solid-soluted carbon having a concentration of 1x1016-1x1017 atoms/cm3 and solid-soluted oxygen having a concentration of 1.4x1018-1.6x1018 atoms/cm3.