[advanced semiconductor process technology series] SOI Technology (Part 1)

SOI Technical introduction

20 century 80 years , Researchers use a layer of insulating material embedded between the substrate and the thin silicon layer on the surface , Develop new silicon on insulator （SOI） material ,SOI The structure of the material is a thin layer of silicon on the surface – Silicon dioxide insulating layer material – Silicon substrate , Integrated circuits are made on the surface of a thin layer of silicon .

Whether it's a general silicon wafer or SOS wafer , Are grown on the bottom single crystal , But there is no way to grow single crystals on oxides , Made in the industry SOI Wafer method is to use embedded or bonding method to form buried oxide to isolate the top silicon film layer and silicon substrate .

manufacture SOI There are three main technologies of wafer ：
The first is oxygen injection separation technology （Separation by Implanted Oxygen - SIMOX）;
The second is bonding etch back technology （Bond and Etch-back SOI - BESOI）;
The third is intelligent cutting technology （Smart-Cut）.

SIMOX technology

SIMOX Technology is the first SOI One of the wafer preparation technologies , It uses ion implantation technology to inject oxygen ions into silicon to form an oxide isolation buried layer , The substrate and the top silicon film layer are isolated by the oxidation isolation buried layer .

SIMOX Technical preparation SOI The wafer process is shown in the figure below ：

(a) It's a bare wafer ;
(b) It's oxygen ion implantation , Through high energy （120 - 200keV） Put a high dose （0.3 - 1.8e18cm-2） Oxygen ions are implanted into silicon wafers , High energy implanted oxygen ions will be distributed below the surface of the silicon wafer ;
(c) High temperature annealing , adopt 3~6 Hours of high temperature （1350℃） Anneal , Oxygen ions in silicon wafer react with silicon , A layer with a thickness of about... Is formed below the surface of the silicon wafer 400nm Silicon dioxide insulation material .

BESOI technology

BESOI Technology is to closely bond two wafers together through bonding technology , The silicon dioxide layer formed between the wafers is used as the oxide buried layer , Then, the thickness of the wafer on one side is thinned to the required thickness by the back engraving technology to form SOI wafer .

BESOI Technical preparation SOI The wafer process is shown in the figure below ：

(a) Prepare two bare wafer substrates A And bare chips B;
(b) Yes, wafer B Conduct thermal oxidation treatment , Use thermal oxidation in wafer B Generate a layer of silicon dioxide insulation on , At the same time, the temperature of oxidation environment is controlled to make the interface between oxide layer and silicon layer low defects and impurities ;
(c) Put the wafer A And wafers B Carry out low temperature bonding and , Using silicon melt bonding （Silicon Fusion Bonding - SFB） Bond another unoxidized wafer to the oxide layer .
(d) The top silicon film is formed by using the back etching technology , Remove excess wafers by means of lithography , Finally, annealing and CMP Form a smooth and clean BESOI Wafer surface .

Smart-Cut technology

Smart-Cut Technology comes from BESOI Technology is derived , First prepare two silicon wafers , A silicon dioxide insulating layer is formed on a wafer by thermal oxidation , Then hydrogen ions are implanted into the silicon wafer by ion implantation , This is the process of processing a wafer , Another wafer does not need special processing .

Smart-Cut Technical preparation SOI Wafer process ：

(a) It is to prepare two bare wafer substrates A And bare chips B;
(b) Yes, wafer B Carry out thermal oxidation and hydrogen ion implantation ;
(c) Put the wafer A And wafers B Carry out low temperature bonding and ;
(d) Peel the wafer by thermal reaction B Form top silicon film , Use high temperature thermal annealing to strengthen the key and , as well as CMP Handle .

PD-SOI technology 、 Warping effect 、 Parasitic bipolar transistor effect 、 Self heating effect 、 Body contact 、FD-SOI See 《【 Semiconductor advanced process technology series 】SOI technology （ Next ）》

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