Backside Plasma Treatment for Semiconductor Image Sensor Chips
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Solution Overview
Problem
The high thermal budget of steam anneal in backside illumination image sensor chip manufacturing adversely affects pixel performance, especially as pixel sizes decrease, leading to increased dark currents.
Innovation Solution
Replacing steam anneal with a dry treatment or plasma treatment without vertical bias, using oxygen as process gases, to form a thin oxide layer and reduce Si—H bonds, thereby improving pixel performance and reducing dark currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam anneal is used to treat the backside of the semiconductor substrate, then the p-type impurity is activated and the surface is passivated, but the high thermal budget adversely affects pixel performance and increases dark currents
Solution Approach 1:
The patent changes the fundamental parameter of the annealing process from thermal (steam anneal at high temperature) to non-thermal (plasma treatment at low temperature). This parameter change allows achieving impurity activation and surface passivation without the high thermal budget that harms pixel performance and increases dark currents in small pixels
2Manufacturing precision
If pixel sizes are reduced to increase sensor resolution, then the sensor density is improved, but the dark currents become increasingly important and the adverse effects of steam anneal become more severe
Solution Approach 1:
By changing from thermal annealing to plasma treatment, the patent eliminates the temperature-related harmful effects that become more severe as pixel size decreases. The low-temperature plasma process avoids generating dark currents while still achieving the necessary impurity activation for small pixels
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 approach enhances pixel performance and reduces dark currents in image sensor chips by eliminating the adverse effects of steam anneal, improving the efficiency of light capture.
Implementation Method 1
A plasma treatment is then performed on the back surface without vertical bias
Implementation Method 2
using oxygen as process gases, to form a thin oxide layer
Data Source
AI summary
A method includes performing a grinding to a backside of a semiconductor substrate, wherein a remaining portion of the semiconductor substrate has a back surface. A treatment is then performed on the back surface using a method selected from the group consisting essentially of a dry treatment and a plasma treatment. Process gases that are used in the treatment include oxygen (O2). The plasma treatment is performed without vertical bias in a direction perpendicular to the back surface.