功能材料4：半导体制造技术2013

1、Basic Properties of Crystal Materials晶体的宏观通性晶体的宏观通性 Gerneral Macro-properties l晶面角守恒性晶面角守恒性 Constancy of interfacial anglesl均匀性均匀性 homogeneityl各向异性各向异性 anisotropyl解理性解理性 cleavagel对称性对称性 symmetryRelationship between the physic properties and micro-symmetry of crystalsDefects of crystals3.2.1 微观缺陷微观缺陷

2、3.2.2 宏观缺陷宏观缺陷 【微观缺陷【微观缺陷】偏离偏离理想理想晶体晶体0 0维维: : 点缺陷点缺陷1 1维维: : 线缺陷线缺陷2 2维维: :面缺陷面缺陷3 3维缺陷维缺陷原子缺陷原子缺陷电子缺陷电子缺陷: 能级跃迁能级跃迁本征缺陷本征缺陷: : 热缺陷热缺陷非本征缺陷非本征缺陷: :杂质缺陷杂质缺陷( (固溶体固溶体) )非化学计量缺陷非化学计量缺陷韧形位错韧形位错固溶体固溶体多晶多晶(陶瓷陶瓷)非晶态非晶态表面界面表面界面晶界晶界表面表面纳米粉体纳米粉体纳米结构纳米结构螺旋位错螺旋位错晶粒晶粒 韧形位错 edge dislocation 螺旋位错 screw dislocatio

3、n特点： 1. 非平衡缺陷 2. 位错单位均为一个格矢，即b (Burgers Vector)3.2.2 宏观缺陷宏观缺陷 韧形位错 edge dislocationEdge dislocation (line defect)位错的移动：滑移螺旋位错 screw dislocation单晶硅中观察到的螺旋位错缺陷单晶硅中观察到的螺旋位错缺陷孪晶界孪晶界小角度晶界小角度晶界高分辨率点电镜：螺旋位错和小角度晶界高分辨率点电镜：螺旋位错和小角度晶界1HRTEM of Screw Dislocations in a Small Angle Grain Boundary Dislocations for

4、m at the interface between the first layer of gallium nitride to be deposited and the sapphire substrate. The dislocations can thread their way into the active layer of the device, but do not seem to degrade the device properties.【观缺陷观缺陷】Macrocopic defects:l开裂开裂 splitting, l包裹体包裹体 inclusionl生长层生长层 g

5、rowth layer l生长条纹生长条纹 growth striationl胞状组织胞状组织 cellular structrue l楔化楔化 wedging包裹体包裹体开裂开裂生长条纹生长条纹 生长层生长层生长层生长层生长条纹生长条纹 Silicon single crystals were grown by the floating-zone method using an infrared image furnace in the wide range of oxygen partial pressure defined at the inlet of the furnace 3.3

6、半导体晶体及晶片制备技术半导体晶体及晶片制备技术Processing Technology of SemiconductorCrystal & its Wafer From sand to wafer3.3.1 概述概述 Introduction lThe outer crust of this planet consists of all kinds of silicates (Si + O + something else). Si, in fact, accounts for about 26 % of the crust, while O about 49 %.lLiquid

7、Si indeed does react with all substances known to man - it is an universal solvent. This makes crystal growth from liquid Si somewhat tricky, because how do you contain your liquid Si? Fortunately, some materials - especially SiO2 - dissolve only very slowly.lBut(!) there will always be some dissolv

8、ed SiO2 and therefore oxygen in your liquid Si, and that makes it hard to produce Si crystals with very low oxygen concentrations. 3.3.2 硅原料处理和提纯硅原料处理和提纯 Producing Raw Silicon and its purifyingSiO2 + 2C = Si + 2CO2000oC Purifying of siWhat we do have to do is to purify the MG-Si - about 109 fold!（a）

9、First, Si is converted to SiHCl3 in a fluid bed Si + 3HCl = SiHCl3 + H2（b）Second, the SiHCl3 is distilled (like wodka), resulting in extremely pure Trichlorosilane（三氯硅烷）（c） Third, high-purity Si is produced by a Chemical Vapor Deposition (CVD) processCVD Schematic diagram 以SiHC3 (8N) 为原料，通过CVD，得到超纯的

10、多晶硅。（hyperpure poly-Si） 1000oC SiHCl3 + H2 Si + 3 HClMore information3.3.3 单晶制备单晶制备 Single Crystal GrowthCzochrolski process 又称：直拉法又称：直拉法 或或 乔赫拉斯法乔赫拉斯法 Essentially, a crystal is pulled out of a vessel containing liquid Si by dipping a seed crystal into the liquid at a surface temperature of the melt

11、 just above the melting point.Everything else determines the quality and homogeneity - crystal growing is still as much an art as a science! Here we only look at one major point, the segregation coefficient kseg of impurity atomsEquilibrium refers to a growth speed of 0 mm/min or, more practically,

12、very low growth rates. On the positive side, the crystal will be cleaner than the liquid, crystal growing is simultaneously a purification method. The negative side: The distribution of impurities - and that includes the doping elements and oxygen - will change along the length of a crystal - a homo

13、geneous doping etc. is difficult to achieve.This is Why practically only As, P, and B are used for doping? Their segregation coefficient is close to 1. (But Bi difficult or impossible).More information【 区熔法区熔法 】Float Zone Crystal Growth 原理：原理：The method was first used for purification taking advanta

14、ge of the small segregation coefficients of many impurities. The impurities contained in the feed material would then prefer to remain in the melt and thus could be swept to the end of the feed stock. 特点特点：Since the melt never comes into contact with anything but vacuum (or inert gases), there is no

15、 incorporation of impurities that the melt picks up by dissolving the crucible material as in the CZ crystal growth method. This is especially true for oxygen, which can not be avoided in CZ crystal growth. FZ crystals therefore are always used when very low oxygen concentrations are important.区熔法原理

16、图区熔法原理图区熔法提纯原理图区熔法提纯原理图3.3.4 晶片技术晶片技术 Wafer Technology晶片抛光晶片抛光 (lapping)3. 4 半导体芯片加工技术Technologies for Processing Semiconductor(From Wafer to Chip)平板印刷技术平板印刷技术 Si氧化技术氧化技术溅射技术溅射技术CVD技术技术外延技术外延技术 分子束外延技术分子束外延技术离子注入技术离子注入技术等离子腐蚀技术等离子腐蚀技术化学腐蚀技术化学腐蚀技术蒸发技术蒸发技术旋式涂布技术旋式涂布技术半导体芯片相关制造技术半导体芯片相关制造技术Si(P)N-WellS

17、iO2N+P+D1A1D2CAPSA2Si(P)SiO2Si(P)SiO2Surface pictureSi(P)SiO2Surface pictureN-WellN-WellSi(P)SiO2Si3N4Surface pictureSi(P)N-WellSiO2Si3N4Surface pictureN-WellSiO2Si(P)Si3N4Surface pictureN-WellSiO2Si(P)Surface pictureN-WellSiO2Si(P)Surface picturePolyN-WellSi(P)Surface pictureSiO2PolyN-WellSi(P)SiO2

18、Surface pictureLPTEOSN-WellSi(P)SiO2PolySpacerSurface pictureN-WellSi(P)SiO2PolySurface pictureSi(P)N-WellSiO2PolySurface pictureN-WellSi(P)SiO2Surface pictureN+P+D1N-WellSi(P)SiO2Surface pictureN+P+D1W1N-WellSi(P)SiO2Surface pictureN+P+D1N-WellSi(P)SiO2Surface pictureN+P+D1ALN-WellSi(P)SiO2Surface

19、pictureN+P+D1ALN-WellSi(P)SiO2Surface pictureN+P+D1ALD2Si(P)Surface pictureN-WellSiO2N+P+D1ALVIAD2Si(P)Surface pictureN-WellSiO2N+P+D1ALA2D2Si(P)N-WellSiO2N+P+D1A1D2CAPSA2CAPSPETEOSTEOSSurface pictureA2A1SiO2-VIA平板印刷技术平板印刷技术 Si氧化技术氧化技术溅射技术溅射技术CVD技术技术外延技术外延技术 分子束外延技术分子束外延技术离子注入技术离子注入技术等离子腐蚀技术等离子腐蚀技术化

20、学腐蚀技术化学腐蚀技术蒸发技术蒸发技术旋式涂布技术旋式涂布技术半导体芯片相关制造技术半导体芯片相关制造技术Lithography Techniques掩模层掩模层光阻层光阻层曝光曝光抗蚀膜显影抗蚀膜显影图案转移图案转移去除光阻层去除光阻层去除掩模层去除掩模层图案层图案层完成图案完成图案电磁波光频部分：紫外、可见、红外电磁波光频部分：紫外、可见、红外50.2 eV能量能量eV极远紫外光刻技术极远紫外光刻技术EUV lithography TechniquesThermal oxidation. This means that a solid state reaction (Si + O2 = S

21、iO2) is used: Just expose Si to O2 at sufficiently high temperatures and an oxide will grow to a thickness determined by the temperature and the oxidation time.【 】【外延技术外延技术】Epitaxy单晶衬底单晶衬底 + 单晶膜单晶膜 外延生长外延生长 Points:lDoping of the epitaxial layer with high precision (e.g. 5 Wcm 5%), and the doping is

22、usually very different from that of the substrate. The picture on the right symbolizes that by the two differently colored doping atoms.lPrecise thickness control, e.g. d = 1,2 m 10% over the entire wafer, from wafer to wafer and from day to day. Now there is a challenge: If you met the first point

23、and thus cant tell where the interface is - how do you measure the thickness? (The answer: Only electronically, e.g. by finding the position of the pn-junction produced).lCleanliness: No contaminants diffusing into the substrate and the epitaxial layer are allowed.Many materials that we wish to depo

24、sit have very low vaporpressures and thus are difficult to transport via gases.One solution is to chemically attach the metal (Ga, Al, Cu,etc) to an organic compound that has a very high vaporpressure. The organic-metal bond is very weak and can be broken viathermal means on wafer, depositing the me

25、tal with the highvapor pressure organic being pumped away.Metal Organic Chemical Vapor DepositionMBE (Molecular Beam Epitaxy). 背景：超晶格材料要求，是CVD外延技术的延伸。特点：每层10nm 精度1个原子层MBE: 1 m/h (CVD 1-10 m/min). Every atom reaching the surface of the heated substrate has enough time to migrate around and find his p

26、lace to build up a new crystal lattice. 超晶格超晶格superlattice超晶格超晶格 superlattice 【溅射技术溅射技术】Sputtering or Sputter Deposition(物理气相沉积-1)lThe target atoms hit the substrate with an energy large enough so they get stuck, but not so large as to liberate substrate atoms. Sputtered layers therefore usually sti

27、ck well to the substrate (in contrast to other techniques, most notably evaporation).lAll atoms of the target will become deposited, in pretty much the same composition as in the target. It is thus possible, e.g., to deposit a silicide slightly off the stoichiometric composition (advantageous for al

28、l kinds of reason). In other words, if you need to deposit e.g. TaSi2 - x with x 0,01 - 0,1, sputtering is the way to do it because it is comparatively easy to change the target composition.lThe target atoms hit the substrate coming from all directions. In a good approximation, the flux of atoms lea

29、ving the target at an angle F relative to the normal on the target is proportional to cos F. This has profound implications for the coverage of topographic structures.lHomogeneous coverage of the substrate is relatively easy to achieve- just make the substrate holder and the target big enough. The p

30、rocess is also relatively easily scaled to larger size substrates - simply make everything bigger.More information【离子注入技术离子注入技术】Ion Implantation(物理气相沉积-2)What is ion implantation? Ions of some material - almost always the dopants As, B, P - are implanted, i.e. shot into the substrate原原理理图图离子注入技术在高技术陶瓷用于表面改性离子注入技术在高技术陶瓷用于表面改性only Sb (as dopant) and occasional