Partie SC finie

Article_Scientifique/lowtech.tex

@@ -11,14 +11,17 @@ The most challenging part of this section is the replacement of semiconductor pa
 
 \begin{enumerate}
 	\item ST Microelectronics Labège-Innopôle (formerly Exagan, formerly CEA-Leti) 
+	\item LAAS-CNRS (Laboratoire d'Analyse et d'Architecture des Systèmes - Centre National des Recherches Scientifiques) semiconductor lab
 	\item AIME (Atelier Interuniversitaire de Micro-nano Électronique) on-campus at INSA Toulouse
 \end{enumerate}
 
 ST Microelectronics at Labège designs and manufactures gallium nitride transistors under the commercial designation STPOWER PowerGaN, this confirmed by a colleague who visited the plant and engineering teams in late 2022, Etienne Gadefait. Gallium nitride transistors are great for high speed power electronics % ref https://www.st.com/en/power-transistors/powergan.html
 but this is a very recent technology, and none of the big material players in GaN are European, let alone French or Occitanian (US, China, Japan and India are predominant). % ref https://us.metoree.com/categories/7137/
- Because of this and very high costs, we chose to consider this a supply chain-constrained technology, which could not be relied on in a non-global future, and we moved on to option 2; AIME.
+ Because of this and very high costs, we chose to consider this a supply chain-constrained technology, which could not be relied on in a non-global future, and we moved on to other options.
  
-The AIME is a small research lab located on our campus. Their capabilities and projects were not publicly available, so we decided to contact them. We met two researchers Reasmey Tan and Jean-Baptiste Lincelles to enquire about the manufacturability of certain components, and eventual costs. The AIME specialises in logic circuits, and has not developed any power components at least a decade. Therefore, the research teams have not maintained any know-how in power semiconductors. However, they were very interested in developing this field in their lab, and came with the following proposal to start, based on their existing knowledge. Here are the AIME capabilities, prices and proposal:
+The LAAS semiconductor lab was deemed less reachable and more technologically advanced than the AIME semiconductor lab, as we were told they mostly did research on carbon nanotubes and other fancy semiconductor materials. We therefore chose not to contact the LAAS, and 
+
+The AIME is a small research lab located on our campus. Their capabilities and projects were not publicly available, so we decided to contact them. We met two researchers Reasmey Tan and Jean-Baptiste Lincelles to enquire about the manufacturability of certain components, and eventual costs. The AIME specialises in logic circuits, and has not developed any power components at least a decade. Therefore, the research teams have not maintained any know-how in power semiconductors. However, they were very interested in developing this field in their lab, and came with a proposal to start, based on their existing knowledge. Here are some of AIME's capabilities and prices:
 
 \begin{table}[htbp]
 	\caption{AIME capabilities}
@@ -28,41 +31,54 @@ The AIME is a small research lab located on our campus. Their capabilities and p
 		\toprule
 		\textbf{Proposal or capability} & \textbf{Value, if relevant} & \textbf{Price, if relevant} \\
 		\midrule
-		Silicon wafer & 2'' (~50mm) & 10 € \\
+		Silicon wafer & 2'' ($\sim$50mm) & 10 € \\
-		Epitaxial Silicon Carbide wafer & 2'' (~50mm) & 100-200 €   \\
+		Epitaxial "fancy" wafer & 2'' ($\sim$50mm) & 100-200 €   \\
-		Lithography mask &  10µm width & 300 € \\
+		AIME-made lithography mask &  10µm canal width & 300 € \\
-		Lab rental & 1 day & ~2000 € \\
+		Lab rental & 1 day & $\sim$2000 € \\
-		Transistor canal width & ~1µm \\
+		Transistor canal width & $\sim$1 µm \\
-		Hardware cost 							 & \\
+		Drain-source on resistance & 1 k\textOmega \\
-		Dynamic response 					&  \\
 		\bottomrule
 	\end{tabular}
 \end{table}
 
+The proposed project was based on their logic transistors, scaled up not in size, but in number. As seen in the table \ref{tab:AIME_capabilities}, one of their small logic transistors has a resistance of:
+
+\begin{equation}
+	R_{DS_{on}} \approx 1\ k\Omega
+\end{equation}
+
+As we need a transistor capable of passing 28 Amperes of current, this resistance is unacceptable. Therefore, they proposed to put a great number of transistors in parallel to reduce $R_{DS_{on}}$, on a big surface to better distribute and dissipate the heat (the heat calculations were not made). We can also note here that AIME does not have packaging technology to dissipate high head loads, which could be resolved using external specialist companies (expensive) or making a very thermally efficient transistor. The current also makes the attachment of wires more complicated, as the general relation (not taking into consideration the skin effect in larger diameters) they gave me gives:
+
+\begin{equation}
+	1\ \frac{mA}{\mu m\ diameter} \Rightarrow diameter =  2,8 cm
+\end{equation}
+
+Which is extremely unrealistic for a small component and needs to be investigated further. The second problem is the voltage, as the small signal transistors they have are made for lower voltages. Therefore, we needed a thicker MOSFET with a thicker n- drift layer between the drain and source to prevent breakdown, which results in us needing a fancy and expensive epitaxial wafer instead of a cheap one. This results in another problem, an even higher Drain-source on resistance $R_{DS_{on}}$, multiplying the already great number of transistors by a good factor. At the end, this is the project they proposed:
+
 \begin{table}[htbp]
 \caption{The project proposed by the AIME}
 \label{tab:AIME_project}
 \centering
 \begin{tabular}{lcc}
 \toprule
-\textbf{Proposal or capability} & \textbf{Value} & \textbf{Price, if relevant} \\
+\textbf{Proposal or capability} & \textbf{Value, if relevant} & \textbf{Price, if relevant} \\
 \midrule
-Wafer size 	   &  \\
+Transistor count & $\sim$400 000 & \\
-Low-load efficiency 				  &   \\
+Die size & 1-2 cm$^2$ & \\
-High-speed switching loss     &  \\
+Wafer & 2'' ($\sim$50mm) epitaxial & 100-200 €  \\
-Position sensor requirement &  \\
+Dies per wafer & 1 & 100-200 € per die \\
-Implementation complexity  & \\
+Lab rental & subsidised &  reason: academia  \\
-Hardware cost 							 & \\
+Masks needed & 4 & 1200 € \\
-Dynamic response 					&  \\
+Dies per set of masks & $>$ 1000 dies & \\
 \bottomrule
 \end{tabular}
 \end{table}
 
-
+These costs are much larger than what we have for this project, but are not insurmountable for a department like the GEI. This project also needs a lot of time or more people to be made, more than what we have at our disposal. The researchers were very interested in collaborating on such a project in the future, and considered it very strongly as a replacement for the current AIME project for the 5th year PTP Energie students (currently a CO2 sensor), with GEI's backing and funding. 
 
 \subsection{Replacing an IC}
 
-Replacing the IC of a motor controller requires using traditional logic gates. This approach is 
+Replacing the IC of a motor controller requires using traditional logic gates. This approach can be done in several methods
 
 \subsection{Power components}
 

Article_Scientifique/main.tex

@@ -15,6 +15,7 @@
 \usepackage{xcolor}
 \usepackage{tikz}
 \usepackage{graphicx}
+\usepackage{textgreek}
 \usetikzlibrary{decorations.pathmorphing}
 \usetikzlibrary{positioning}