DMOS Source Regulation Layer for Gate Bird's Beak Stability
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Solution Overview
Problem
Conventional DMOS semiconductor devices face irregular characteristics and low yield due to the formation of gate bird's beak, which affects the stability and shape of the source layer, leading to irregular channel length and performance.
Innovation Solution
A DMOS semiconductor device with a source forming regulation layer that extends horizontally beyond the region where the gate bird's beak occurs, allowing for stable source layer formation without being affected by the beak's irregularity, achieved by implanting ions of an impurity element with self-alignment and oblique ion implantation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal oxidation treatment is carried out after body layer formation to form source and back gate layers, then the source layer and back gate layer are formed, but the gate oxide film at the end of the gate is affected producing an unstable gate bird's beak with irregular thickness and shape
Solution Approach 1:
The patent applies preliminary action by forming the regulation layer in advance before the thermal oxidation treatment that creates the gate bird's beak. The regulation layer is formed by ion implantation into the body layer prior to gate oxide film formation, establishing a controlled impurity distribution that will regulate source layer formation regardless of subsequent gate bird's beak irregularities.
Solution Approach 2:
The regulation layer acts as an intermediary between the body layer and the source layer. It mediates the effect of gate bird's beak irregularities by providing a buffer zone with controlled impurity concentration, thereby stabilizing the source layer formation process and reducing the impact of gate end irregularities on final device characteristics.
2Ease of manufacture
If the source layer is formed by self-alignment ion implantation using the gate as mask, then the source layer is formed in the body layer, but the source layer is affected by the irregular thickness and shape of the gate bird's beak resulting in irregular characteristics
Solution Approach 1:
The regulation layer serves as an intermediary structure between the body layer and the source layer formation process. It absorbs and mitigates the irregularities from the gate bird's beak by providing a controlled impurity distribution profile, thereby enabling self-alignment ion implantation to proceed while maintaining source layer regularity.
Solution Approach 2:
The patent changes the impurity concentration parameter by forming the regulation layer with a specific impurity concentration that is lower than the body layer. This parameter change creates a gradient that regulates diffusion and implantation processes, ensuring that the source layer forms with consistent characteristics despite variations in gate bird's beak geometry.
3Manufacturing precision
If the channel length is defined by the difference in diffusion depth between body layer and source layer, then the channel length is established, but irregularities in source layer position due to gate bird's beak cause yield reduction
Solution Approach 1:
The regulation layer acts as an intermediary that stabilizes the interface between the body layer and source layer. By controlling impurity distribution in this intermediate region, it ensures consistent channel length definition while reducing variability caused by gate bird's beak irregularities, thereby improving device yield.
Solution Approach 2:
The regulation layer is formed in advance to establish a controlled impurity distribution profile before source layer formation. This preliminary action ensures that the channel length, defined by the difference in diffusion depth between body and source layers, is consistently determined regardless of subsequent variations in gate bird's beak morphology.
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 configuration ensures a stable source layer with precise channel length, reducing irregularities and increasing the yield of the DMOS semiconductor device by preventing the negative impact of gate bird's beak irregularities.
Implementation Method 1
an annealing treatment (thermal oxidation treatment) is carried out
Implementation Method 2
by implanting ions of an impurity element of a first conduction type from the ion implantation opening
Implementation Method 3
diffusively forms the body layer 104 in the epitaxial growth layer 101 by implanting ions of a p-type impurity element
Data Source
AI summary
A DMOS type semiconductor device and a method for manufacturing the same are provided. An isolation oxide layer with an ion implantation opening is formed on a semiconductor. A gate oxide film is formed on the semiconductor within the ion implantation opening. A gate is formed on the isolation oxide layer and the gate oxide film. A body layer diffusively formed in the semiconductor by implanting ions of an impurity element having a first conduction type from the ion implantation opening. A regulation layer which is shallower than the body layer is diffusively formed in the body layer by implanting ions of an impurity element having a second conduction type opposite to the first conduction type from the ion implantation opening. A source layer is diffusively formed in the regulation layer by implanting ions of an impurity element having the second conduction type from the ion implantation opening. The regulation layer is formed so as to horizontally extend beyond a region in which a gate bird's beak occurs from an end of the gate toward underlying layers of the gate.