晶片边缘磨削控制方法研究

对半导体工艺中晶片的边缘磨削技术进行了论述,分析了晶片边缘磨削技术的特点,在此基础上,提出了一种高效、可靠的晶片边缘磨削方法.该方法基于单轴电机进给控制,通过控制软件来实现对晶片边缘及定位边的磨削.首先确定晶片定位边位置,然后通过精确控制承片台驱动电机的旋转角度来磨削晶片圆边,对于定位边的磨削,需要精确控制承片台驱动电机的旋转角度和进给电机的进给量,通过两电机联动控制,完成定位边磨削.该方法控制精度高,成功实现了在单轴电机驱动下的晶片圆边及定位边磨削.试验结果证明,该方法可靠、稳定、高效,并降低了设备硬件成本.     

磨削工艺对晶片表面粗糙度的影响

磨削工艺直接影响着磨削后晶片的参数,在这些参数中,表面粗糙度是鉴别晶片几何参数好坏的重要指标之一。分析了磨削工艺中砂轮粒度、砂轮进给速度对表面粗糙度的影响。     

磨削工艺对晶片TTV的影响

磨削工艺直接影响着磨削后晶片的表面质量参数,在这些参数中,总厚度变化(TTV)是鉴别晶片几何参数好坏的重要指标之一.分析了磨削工艺中承片台转速、主轴进给速度、主轴转速对TTV的影响.     

石英晶片外观缺陷对频率的影响

研究了石英晶片外观缺陷对频率的影响。石英晶片其自身存在的外观缺陷包括:崩边、玷污、缺角等,这些缺陷可能会影响到成品石英晶体电参数的性能,例如影响石英晶体的频率特性、电阻特性、DLD特性等。目前石英晶片在镀电极前均需要进行外观缺陷检测,国内大多采用人工目测检测的方式,光学方法的石英晶片的缺陷自动检测技术还不成熟。无论哪种检测方法,都具有比较大的主观性,目前还没有建立有关石英晶片对石英晶体电参数的影响关系的研究报道。因此需要研究石英晶片外观缺陷对石英晶体电参数的影响的对应关系,以便能更准确地分选出对石英晶片电参数有影响的存在外观缺陷的石英晶片。     

提高锗圆片材料利用率

一、概况在小圆片的生产过程中,原料费要占全部费用的95％左右。因而,在生产中设法提高成品率降低原料费,是保证产品质量提高经济效益最重要的途径。这个问题是锗材料厂和有关晶体管厂十分注意和关心的问题。小圆片在切割过程中,产品圆周边缘出现局部破裂脱落现象称之为“崩边”,它严重地影响小圆片生产成品率,也影响下一步晶体管的制造质量。因此,减少“崩边”或消除“崩边”又是提高材料利用率降低生产成本非常重     

表面活性剂在P型锗片磨削工艺中的应用

由于锗材料具有优良的抗辐射性能,在航天领域获得了新的应用。在锗单晶片的磨削过程中,砂轮磨损产生的颗粒以及磨削下来的锗屑容易将砂轮阻塞,从而对锗单晶片表面的磨削纹路产生影响。通过试验,在去离子水管路上增加一条表面活性剂管路,可有效减少砂轮阻塞现象,降低砂轮修整的频率,提高了锗磨削片的表面质量。     

砂轮粒径对300 mm Si片双面磨削影响的研究

在直径300mmSi片制备过程中,利用双面磨削技术能获得高精度的表面参数,但同时却会在Si片表面留下明显的磨削印痕,这会影响Si片表面平整度.通过选择#2000和#3000砂轮对Si片进行磨削实验,获得两种型号砂轮磨削出Si片的形貌图、磨削印痕和局部平整度,并分别进行了比较.结果表明,选择粒度更细的#3000砂轮能够有效地弱化Si片表面的磨削印痕,同时改善边缘局部平整度差的问题,从而提高Si磨削片表面的局部平整度.     

变速切割速度曲线对硅片翘曲度的影响

根据线切割机的工作原理,综合考虑了砂浆中磨料在磨削过程中的变化以及单晶直径的变化,确定了变速切割的工艺方法,同时考虑到125 mm单晶直径大、SIC磨削路线长、磨削发热量大,制定了包括线速度、耗线量、砂浆温度、砂浆流量以及各部分温度的工艺参数。通过该工艺参数进行了切割实验,验证了该工艺参数下切割的晶片可以满足要求。     

硅-硅直接键合后硅片的机械减薄过程北大核心

硅-硅直接键合硅片的机械减薄工艺对器件的性能有很大的影响。采用磨削、化学腐蚀和机械/化学抛光的方法对硅-硅直接键合硅片进行减薄加工,分析了减薄过程中各个工序键合片的平整度、弯曲度和翘曲度变化,并对减薄后硅片的厚度均匀性进行了考察。本次实验最终获得了几何参数良好、厚度满足要求且均匀的晶片。磨削过程会使弯曲度和翘曲度升高,可以通过化学腐蚀的方法降低弯曲度和翘曲度,化学腐蚀过程虽然使平整度升高,但可以通过机械/化学抛光的方法降低平整度。采用该减薄技术对直接键合硅片进行机械减薄具有可行性。     

超薄硅片倒角工艺研究

在硅片加工的前期工程中,由于切割成型的硅片存在着边缘崩口、裂纹、应力集中等物理特性差的现象,需用倒角机来对硅片进行边缘磨削加工,以改善硅片的物理性能,随着硅片厚度的减小,硅片边缘越来越容易出现崩边,碎片率也逐渐提升,砂轮寿命也在逐渐降低,硅片的倒角技术逐渐变为一个难题。本文通过对砂轮转速、吸盘转速的改变来开展工艺试验,当加工超薄硅片时适当减小砂轮转速,可明显提高硅片边缘倒角质量;吸盘转速一般稳定在15 mm/s左右时,加工速率相对比较高,边缘质量也会得到最大程度的保证。     

Relationship between wafer fracture reduction and controlling during the edge manufacturing process

Given the trend towards wafers of a larger diameter, microelectronics circuits are driven by modern IC manufacturing technology. Silicon wafer breakage has become a major concern of all semiconductor fabrication lines because silicon wafer is brittle and high stresses are induced in the manufacturing process. Additionally, the production cost is increasing. Even a breakage loss of a few per cent drives up device costs significantly if wafers are broken near completion, but wafer breakage even near the beginning of the process is significant.In this paper, we first point out the approach for the characterization of silicon wafer failure strength empolying a simple drop test, thereby providing a better understanding of the stress accumulated in wafer bulk before failure.This study also presents a brand new method using a charge coupled device (CCD) to capture the cross-section image of the wafer at the wafer edge; the data measured at the edge can be used to diagnose overall wafer strength. Analysis of the image of the wafer edge is used to characterize silicon strength and a simple drop test is conducted to elucidate wafer failure, improving our understanding of the accumulation of stress in wafer bulk before failure.This work presents an approach for characterizing silicon wafer failure strength using a simple drop test, to improve our understanding of the stress accumulated in wafer bulk before failure. However, this work will describe many of the improvements that have resulted in the virtual elimination of wafer breakage due to unknown reasons. According to an analysis based on the material mechanical theory for the bevel lengths (A1, A2), the edge length and the bevel angle (θ) are optimized to design the edge profile of the produced wafer, to prevent wafer breakage. Restated, when proper material and process control techniques are utilized, silicon wafer breakage should be prevented. This work is the first to demonstrate the importance of understanding wafer strength using a simple mechanical approach.     

Relationship between wafer edge design and its ultimate mechanical strength

Due to its brittle nature, high stress-induced in manufacturing process, silicon wafer breakage has become a major concern for all semiconductor fabrication line. Furthermore, the production cost had increased in advanced technology day by day. Even a some-percent breakage loss drives device costs up significantly if wafers are broken near completion. Consequently, wafer breakage even near the beginning of the process is significant. In short words, silicon wafer breakage has become a major concern for all semiconductor fabrication lines, and so high stresses are easily induced in its manufacture process. The production cost is increasing even breakage loss of a few percent significantly drives device costs up, if wafers are broken near completion. Even wafer breakage near the beginning of the process is significant.In this paper, we first point out the approach for the characterization of silicon wafer failure strength employing a simple drop test, thereby providing a better understanding of the stress accumulated in wafer bulk before failure.This study also presents a brand new method using a charge coupled device (CCD) to capture the cross-section image of the wafer at the wafer edge; the data measured at the edge can be used to diagnose overall wafer strength. Analysis of the image of the wafer edge is used to characterize silicon strength and a simple drop test is conducted to elucidate wafer failure, improving our understanding of the accumulation of stress in wafer bulk before failure.A physical model would also be proposed to explain the results. This model demonstrates that the fracture rate of wafers can be reduced by controlling the uniformity of the difference between the front and rear bevel lengths during the wafer manufacturing process.     

3D封装中的圆片减薄技术

随着微电子工业迅猛发展,圆片直径越来越大,当150mm、200mm甚至300mm英寸圆片被减薄到150μm以下时,圆片翘曲和边缘损伤问题变得尤为突出。超薄减薄技术是集成电路薄型化发展的关键技术,它直接影响电路的质量和可靠性。文章从超薄圆片减薄中常见的圆片翘曲和边缘损伤造成的损失出发,分析了圆片翘曲和边缘损伤的原因,提出了相应的改善措施。     

用单片清洗设备进行晶圆背面清洗

晶圆背面的污染降低了半导体器件的成品率,而当器件进入100nm技术节点之后成品率的降低便显得尤为重要。因此,目前众多的器件制造厂家就要求在进行片子正面清洗的同时对其背面也能够实现清洗。由Akrion公司制造的Mach2HP系统就是这样一种单片清洗设备,它具有清洗晶圆正反两面的功能。在起初评价时,设备经过了大量的粒子去除效率的变化。这种大量的变化使我们不能了解这种设备真实的清洗能力。氮化硅(Si3N4)粒子污染的晶片被用以进行粒子去除效率测试。我们发现有Si3N4粒子的晶片引起了背面粒子去除效率的变化。这种含Si3N4粒子的晶片是通过在裸芯片上沉积Si3N4粒子而特意准备的。我们发现,一些较大的Si3N4粒子在晶片清洗时又分解成更小的粒子。如若在清洗之后分解的粒子仍保留在晶片上,它们便会降低晶片总的粒子去除效果。因此,在这些粒子沉积到晶片上之前,这些粒子群需要进一步分解成实际的粒子。经过了解晶片的预习处理,我们实现了这种清洗设备背面清洗效果的评价。     

Surface shape control of the workpiece in a double-spindle triple-workstation wafer grinder

Double-spindle triple-workstation(DSTW) ultra precision grinders are mainly used in production lines for manufacturing and back thinning large diameter(≥300 mm) silicon wafers for integrated circuits.It is important, but insufficiently studied,to control the wafer shape ground on a DSTW grinder by adjusting the inclination angles of the spindles and work tables.In this paper,the requirements of the inclination angle adjustment of the grinding spindles and work tables in DSTW wafer grinders are analyzed.A reasonable configuration of the grinding spindles and work tables in DSTW wafer grinders are proposed.Based on the proposed configuration,an adjustment method of the inclination angle of grinding spindles and work tables for DSTW wafer grinders is put forward. The mathematical models of wafer shape with the adjustment amount of inclination angles for both fine and rough grinding spindles are derived.The proposed grinder configuration and adjustment method will provide helpful instruction for DSTW wafer grinder design.     

降低有源区颗粒状缺陷密度的晶圆倒角优化工艺

基于28 nm先进工艺平台,研究了有源区工艺中大颗粒状缺陷(LPD)的产生机理及优化方案。研究结果表明,LPD的产生与晶圆边缘倒角形状相关,较短的倒角导致晶圆在CVD工艺中产生背面划伤。划伤产生的颗粒在气体作用下浮到晶圆表面,经过后续工艺步骤后,在有源区硬掩膜氧化层表面形成LPD。提出了改善晶圆边缘倒角形状和嵌入NANO喷洒工艺步骤的优化方案,消除了LPD,提高了产品的合格率。     

硅外延工艺与基座的相关性研究

硅外延使用包封SiC的石墨基座,基座的尺寸及基座上承载槽的形貌和硅外延片的滑移位错直接相关。为使高温下Si片内产生的应力不超过滑移位错产生的临界应力,必须使Si片处于均匀的温区。实际使用表明,基座边缘热辐射及热量被气流带走使基座两个边缘温度急剧下降,必须对边缘温区进行补偿及装片时避开基座边缘一定距离;高温时Si片通过基座获得热量并发生形变,基座上承载槽的形貌设计必须兼顾厚度匀匀性及Si片高温时形变的方向。研究表明,金属沾污尤其是重金属催化作用及过腐蚀是影响基座寿命的关键因素。     

基于晶圆减薄工艺的LT减薄片制备

声表面波(SAW)滤波器因其小型化、低插损及高品质因数(Q)值等性能,已广泛应用于移动通信系统中。钽酸锂(LT)/SiO₂/Si结构克服了传统温度补偿型声表面波(TC-SAW)器件制备工艺难的问题,但需减薄该结构上的LT厚度,而减薄过程会导致晶圆表面有损伤残留,影响器件性能。针对这个问题,该文开展了基于减薄与抛光制备LT减薄片的工艺研究,分析了砂轮目数、砂轮与工作台转速、砂轮进给率等减薄参数对LT晶圆表面损伤的影响,以及抛光压力对损伤的去除效果。研究结果表明,在优化的工艺参数下,减薄抛光后晶圆表面粗糙度为0.187 nm,损伤深度小于1 nm,减薄片制备的TC-SAW谐振器的阻抗图和Smith圆图表明晶圆性能和一致性良好。