CN114371551B - A kind of micromirror structure and preparation method thereof - Google Patents
A kind of micromirror structure and preparation method thereof Download PDFInfo
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Abstract
本发明涉及微纳加工技术领域,特别涉及一种微镜结构及其制备方法。衬底晶圆包括相对的第一表面和第二表面,所述驱动电极层设置在所述第一表面;所述衬底晶圆和所述驱动电极层上设有通孔;所述第一绝缘层设置在所述驱动电极层的表面和所述通孔的内壁上;所述支撑梁的第一端穿过所述通孔与所述固定层连接,所述支撑梁与所述通孔之间存在第一预设间隙;所述固定层设置在所述第二表面;所述驱动电极层中设有第一驱动电极、第二驱动电极和屏蔽电极;所述微镜设置在所述支撑梁的第二端上,所述微镜与所述第一绝缘层之间存在第二预设间隙。本申请实施例所述的微镜结构可以在减小单元尺寸的同时保证微镜的面内横向位移可与入射光波长相比拟。
The invention relates to the technical field of micro-nano processing, in particular to a micromirror structure and a preparation method thereof. The substrate wafer includes an opposite first surface and a second surface, and the driving electrode layer is arranged on the first surface; the substrate wafer and the driving electrode layer are provided with through holes; the first An insulating layer is disposed on the surface of the driving electrode layer and the inner wall of the through hole; the first end of the support beam is connected to the fixed layer through the through hole, and the support beam is connected to the through hole There is a first preset gap between them; the fixed layer is arranged on the second surface; the first driving electrode, the second driving electrode and the shielding electrode are arranged in the driving electrode layer; the micromirror is arranged on the On the second end of the support beam, there is a second preset gap between the micromirror and the first insulating layer. The micromirror structure described in the embodiments of the present application can reduce the unit size while ensuring that the in-plane lateral displacement of the micromirror is comparable to the wavelength of the incident light.
Description
技术领域technical field
本发明涉及微纳加工技术领域,特别涉及一种微镜结构及其制备方法。The invention relates to the technical field of micro-nano processing, in particular to a micromirror structure and a preparation method thereof.
背景技术Background technique
集成微镜通过微镜运动实现对激光光束的调制,使激光光束实现空间扫描,是激光雷达等系统的核心器件。The integrated micromirror realizes the modulation of the laser beam through the movement of the micromirror, so that the laser beam can realize spatial scanning, and is the core device of systems such as lidar.
集成微镜是指采用微机电系统技术(Micro Electro-Mechanical System,MEMS)制作在硅片等圆片上的可运动的微小镜子。它的运动方式大致可分为两类。一类是微镜作偏离其本身平面的运动,例如德州仪器公司的数字微镜器件(Digital Mirror Device,DMD),镜面绕平行于圆片表面的支撑轴作偏转运动。另一类微镜则是在其本身平面内作平行于圆片表面的运动,例如加州大学伯克利分校的Wang Youmin等人发表的MEMS光学相控阵(Youmin Wang,Guangya Zhou,Xiaosheng Zhang,Kyungmok Kwon,Pierre-A.Blanche,Nicholas Triesualt,Kyoung-Sik Yu,and Ming C.Wu,2D broadband beamsteering withlarge-scale MEMS optical phased array,Optica,Vol.6,No.5,2019,pp.557-562)采用在面内运动的表面制作了光栅的微镜阵列实现对激光光束的调制。The integrated micromirror refers to a movable micromirror fabricated on a wafer such as a silicon wafer using Micro Electro-Mechanical System technology (Micro Electro-Mechanical System, MEMS). Its movement mode can be roughly divided into two categories. One is that the micromirror moves away from its own plane, such as the digital mirror device (Digital Mirror Device, DMD) of Texas Instruments, where the mirror surface deflects around a support axis parallel to the surface of the wafer. Another type of micromirror is to move parallel to the surface of the wafer in its own plane, such as the MEMS optical phased array (Youmin Wang, Guangya Zhou, Xiaosheng Zhang, Kyungmok Kwon published by Wang Youmin of the University of California, Berkeley et al. ,Pierre-A.Blanche,Nicholas Triesualt,Kyoung-Sik Yu,and Ming C.Wu,2D broadband beamsteering with large-scale MEMS optical phased array,Optica,Vol.6,No.5,2019,pp.557-562) A micromirror array with a grating fabricated on a moving surface is used to modulate the laser beam.
静电驱动是MEMS微镜阵列的常用驱动方式。静电驱动的面内运动微镜阵列的设计与制造难点主要来源于在减小微镜单元尺寸的同时保持足够的横向驱动位移的矛盾。Electrostatic drive is a common drive method for MEMS micromirror arrays. The difficulty in the design and manufacture of electrostatically driven in-plane moving micromirror arrays mainly comes from the contradiction of maintaining sufficient lateral driving displacement while reducing the size of the micromirror unit.
为了提高调制的作用,必须减小微镜单元尺寸并增加微镜单元数量。但是另一方面,激光雷达等光学应用要求每个微镜单元的最大位移必须至少大于入射光波长的一半,才能实现±π的相位调节(Youmin Wang,Guangya Zhou,Xiaosheng Zhang,Kyungmok Kwon,Pierre-A.Blanche,Nicholas Triesualt,Kyoung-Sik Yu,and Ming C.Wu,2D broadbandbeamsteering with large-scale MEMS optical phased array,Optica,Vol.6,No.5,2019,pp.557-562)。由于红外线的波长超过700nm,微镜的横向位移必须超过±350nm。另一方面,为了提高像素数量,每个微镜单元的边长必须缩小到几十微米量级。而为了使边长仅为几十微米的结构实现超过±350nm的位移,对支撑梁和驱动结构的设计提出了很大的挑战。In order to improve the effect of modulation, the size of the micromirror unit must be reduced and the number of micromirror units must be increased. But on the other hand, optical applications such as lidar require that the maximum displacement of each micromirror unit must be at least greater than half the wavelength of the incident light in order to achieve ±π phase adjustment (Youmin Wang, Guangya Zhou, Xiaosheng Zhang, Kyungmok Kwon, Pierre- A. Blanche, Nicholas Triesualt, Kyoung-Sik Yu, and Ming C. Wu, 2D broadband beamsteering with large-scale MEMS optical phased array, Optica, Vol.6, No.5, 2019, pp.557-562). Since the wavelength of infrared rays exceeds 700nm, the lateral displacement of the micromirror must exceed ±350nm. On the other hand, in order to increase the number of pixels, the side length of each micromirror unit must be reduced to the order of tens of microns. However, in order to achieve a displacement of more than ±350 nm in a structure with a side length of only tens of microns, it poses a great challenge to the design of the supporting beam and the driving structure.
当采用平面内双端固支梁作为微镜支撑结构时,至少需要两根双端支撑梁才能保证微镜在面内平动,其倔强系数为When the in-plane double-end fixed beam is used as the micromirror support structure, at least two double-end support beams are needed to ensure the translational movement of the micromirror in the plane, and the stiffness coefficient is
式中E为杨氏模量,h、b、L分别为梁的厚度、宽度和长度。由上式可得倔强系数与支撑梁长度的三次方成反比,而常规制作在面内的MEMS支撑梁长度与微镜单元的边长成比例,缩小微镜单元尺寸意味着缩小支撑梁的长度L。为了避免弹性系数随L减小而快速增加,必须减小梁宽度b。Youmin Wang等人采用了宽度仅为300nm的支撑梁来保证微镜的位移能够满足应用需求(Youmin Wang,Guangya Zhou,Xiaosheng Zhang,Kyungmok Kwon,Pierre-A.Blanche,Nicholas Triesualt,Kyoung-Sik Yu,and Ming C.Wu,2D broadbandbeamsteering with large-scale MEMS optical phased array,Optica,Vol.6,No.5,2019,pp.557-562)。300nm宽的梁不仅增加了光刻、刻蚀等工艺的难度,也会因为位移大于梁宽度而增加位移非线性效应,从而增加控制系统的复杂性。In the formula, E is Young's modulus, h, b, L are the thickness, width and length of the beam, respectively. From the above formula, it can be obtained that the stubbornness coefficient is inversely proportional to the cube of the length of the support beam, while the length of the MEMS support beam conventionally fabricated in the plane is proportional to the side length of the micromirror unit. Reducing the size of the micromirror unit means reducing the length of the support beam L. In order to avoid a rapid increase in the modulus of elasticity as L decreases, the beam width b must be reduced. Youmin Wang et al. used a support beam with a width of only 300nm to ensure that the displacement of the micromirror can meet the application requirements (Youmin Wang, Guangya Zhou, Xiaosheng Zhang, Kyungmok Kwon, Pierre-A.Blanche, Nicholas Triesualt, Kyoung-Sik Yu, and Ming C. Wu, 2D broadband beamsteering with large-scale MEMS optical phased array, Optica, Vol.6, No.5, 2019, pp.557-562). The 300nm wide beam not only increases the difficulty of lithography, etching and other processes, but also increases the nonlinear effect of displacement because the displacement is greater than the width of the beam, thus increasing the complexity of the control system.
为了实现大于入射红外线半波长的驱动位移,不仅要求支撑梁的倔强系数小,还要求静电驱动力足够大。由于静电力随极板间隙的增加而迅速减小,而法向驱动方式存在吸合效应,其极板间隙必须大于位移的3倍,难以在较低的电压下得到足够的静电力。微镜一般需要采用横向驱动方式,其静电力为In order to realize the driving displacement greater than the half-wavelength of the incident infrared rays, not only the stubborn coefficient of the supporting beam is required to be small, but also the electrostatic driving force is required to be sufficiently large. Since the electrostatic force decreases rapidly with the increase of the plate gap, and there is a pull-in effect in the normal driving mode, the plate gap must be greater than 3 times the displacement, and it is difficult to obtain sufficient electrostatic force at a lower voltage. The micromirror generally needs to be driven laterally, and its electrostatic force is
式中ε和ε0分别为相对介电常数和真空介电常数,V为驱动电压,d0为极板间隙,n为电极对的数量。为了在较低电压下获得足够的静电力,必须增加电极对数量n并减小d0。电极对数量n显然也是受到微镜单元尺寸限制的。Youmin Wang等人采用了宽度仅为300nm的极板间隙,并通过窄电极提高电极对数量(Youmin Wang,Guangya Zhou,XiaoshengZhang,Kyungmok Kwon,Pierre-A.Blanche,Nicholas Triesualt,Kyoung-Sik Yu,andMing C.Wu,2D broadband beamsteering with large-scale MEMS optical phasedarray,Optica,Vol.6,No.5,2019,pp.557-562)。窄间隙不仅对光刻、刻蚀工艺提出了很高的要求,还要求腐蚀形成的侧壁粗糙度必须显著小于间隙尺寸。Where ε and ε0 are the relative permittivity and the vacuum permittivity, respectively, V is the driving voltage, d0 is the plate gap, and n is the number of electrode pairs. In order to obtain sufficient electrostatic force at lower voltages, it is necessary to increase the number of electrode pairs n and decrease d0. The number n of electrode pairs is obviously also limited by the size of the micromirror unit. Youmin Wang et al. adopted a plate gap with a width of only 300nm, and increased the number of electrode pairs through narrow electrodes (Youmin Wang, Guangya Zhou, Xiaosheng Zhang, Kyungmok Kwon, Pierre-A.Blanche, Nicholas Triesualt, Kyoung-Sik Yu, and Ming C. Wu, 2D broadband beamsteering with large-scale MEMS optical phase array, Optica, Vol.6, No.5, 2019, pp.557-562). The narrow gap not only puts high requirements on the photolithography and etching process, but also requires that the roughness of the sidewall formed by etching must be significantly smaller than the size of the gap.
发明内容Contents of the invention
本申请提出一种梁垂直于硅片表面的微镜结构,微镜结构的侧视图如图1所示,并如下所述:This application proposes a micromirror structure in which beams are perpendicular to the surface of the silicon wafer. The side view of the micromirror structure is shown in Figure 1 and described as follows:
衬底晶圆101的正面为第一表面,反面为第二表面。微镜104由垂直于硅片表面的支撑梁103支撑,支撑梁103嵌在衬底晶圆101上开的孔内部,并通过第二表面上的固定层102锚定在衬底晶圆101上。微镜104、支撑梁103与第二表面上的固定层102均由多晶硅制作。微镜104与衬底晶圆101表面平行。微镜104表面可制作光学结构107,光学结构107可以是光栅、纳米光学结构等。光学结构107的具体材料和结构不是本申请的重点关注内容,在此不作详细叙述。本申请仅要求光学结构107能够耐受释放结构的腐蚀工艺。第二表面上的固定层102与衬底晶圆101间有或没有第二第二绝缘层1066都是可以的。当没有第二第二绝缘层1066时,第二表面上的固定层102与衬底晶圆101连接到同一电位。The front side of the
第一驱动电极121、第二驱动电极122与屏蔽电极123制作在衬底晶圆101的第一表面一侧,第一驱动电极121、第二驱动电极122与屏蔽电极123由同一层材料制成,可以是单晶硅或多晶硅材料。第一驱动电极121、第二驱动电极122与屏蔽电极123上表面的起伏小于10nm。第一驱动电极121、第二驱动电极122、微镜104、支撑梁103和第二表面上的固定层102的掺杂类型相同,记为第一掺杂类型,第一掺杂类型可以任意选择,即可以是P型或N型。屏蔽电极123的掺杂类型与第一掺杂类型相反,记为第二掺杂类型,即当第一掺杂类型为P型时第二掺杂类型为N型,当第一掺杂类型为N型时第二掺杂类型为P型。屏蔽电极123与第一驱动电极121、第二驱动电极122间存在PN结,并且工作时所述的PN结始终处于反偏状态,即N区电压高于P区电压。第一驱动电极121、第二驱动电极122与屏蔽电极123上表面覆盖第一绝缘层105,下表面可以制作第二绝缘层106,也可以不制作第二绝缘层106。当第一驱动电极121、第二驱动电极122、屏蔽电极123与衬底晶圆101间有第二绝缘层106时,衬底晶圆101的掺杂类型没有限制。当第一驱动电极121、第二驱动电极122、屏蔽电极123与衬底晶圆101间没有第二绝缘层106时,衬底晶圆101的掺杂类型为第二掺杂类型,与第一驱动电极121、第二驱动电极122间存在PN结,并且所述的PN结在工作时始终处于反偏状态。The
微镜104与第一绝缘层105间有第二预设间隙112,支撑梁103与衬底晶圆101间有第一预设间隙111,因此微镜104可在与衬底晶圆101表面平行的平面内作一维或二维运动。第二预设间隙112的厚度在10nm到3微米范围内。第一预设间隙111的宽度大于工作波长,且小于等于3微米。微镜104上与支撑梁103连接的连接点附近区域为第一区域,为了避免支撑梁103与微镜104的连接点附近可能出现的不平整对微镜横向运动的影响,在第一区域微镜104与与第一绝缘层105间的间隙形成第三预设间隙113,第三预设间隙113的厚度等于第一预设间隙111的宽度。There is a
屏蔽电极123位于微镜104的正下方,第一驱动电极121与第二驱动电极122布置在微镜104的两边,俯视图如图2所示。驱动电压的极性需保证屏蔽电极123与第一驱动电极121、第二驱动电极122间的PN结处于反偏状态。当第一掺杂类型为P型、第二掺杂类型为N型时,第一驱动电极121与第二驱动电极122上施加的驱动电压低于屏蔽电极123上的电压,即采用相对于屏蔽电极123为负的电压作为驱动电压。当第一掺杂类型为N型、第二掺杂类型为P型时,第一驱动电极121与第二驱动电极122上施加的驱动电压高于屏蔽电极123上的电压,即采用相对于屏蔽电极123为正的电压作为驱动电压。The
优选的,为了增加静电力,微镜104和第一驱动电极121、第二驱动电极122可以采用俯视图如图3所示的结构设计。微镜104采用梳状结构。即微镜104的两侧分别设有一个或者多个缺口,两侧的缺口位置对称,形成类似于两侧带梳齿的梳子结构。第一驱动电极121位于梳齿的一边并连接在一起,第二驱动电极122位于梳齿另一边并连接在一起。图3中未画出光学结构107。为了提高光学结构的填充率,光学结构107可以制作成矩形,俯视图如图4所示,图中仅画出光学结构107、微镜104和支撑梁103,剖面图如图5所示。Preferably, in order to increase the electrostatic force, the
为了实现上述结构,提出如下工艺流程:In order to realize the above structure, the following technological process is proposed:
在衬底晶圆101上制作第二绝缘层106和第一多晶硅层,并对第一多晶硅层进行掺杂,掺杂类型为第二掺杂类型,掺杂浓度低于第一驱动电极121和第二驱动电极122的掺杂浓度。第一多晶硅层用于形成驱动电极层120。第二绝缘层106和驱动电极层120需能够耐受后续牺牲层腐蚀工艺。该步工艺也可以省略,此时衬底晶圆101需采用第二掺杂类型的硅晶圆。Fabricate the second insulating
制作盲孔108,盲孔108穿过第二绝缘层106和驱动电极层120并终止在衬底晶圆101内。盲孔108的深度近似等于支撑梁103的长度,在衬底晶圆101平面内的截面形貌可以是矩形、正方形、圆形等,在衬底晶圆101平面内的尺度等于支撑梁103在平面内的尺度加上第二间隙13宽度的2倍。完成后的剖面如图6所示。
淀积制作第一绝缘层105,完成后剖面如图7所示。第一绝缘层105需能够耐受后续牺牲层腐蚀工艺。The first insulating
从衬底晶圆101的第二表面进行腐蚀,暴露出盲孔108内第一绝缘层105的底部,腐蚀深度近似等于衬底晶圆101的厚度减去盲孔108的深度,完成后的剖面如图8所示。Etching is carried out from the second surface of the
从衬底晶圆101的第二表面进行干法刻蚀,去除盲孔108底部绝缘层,完成后的剖面如图9所示。Dry etching is performed from the second surface of the
均匀淀积第一牺牲层131,第一牺牲层131均匀覆盖衬底晶圆101正反表面和通孔内壁,第一牺牲层131的厚度等于第一预设间隙111的宽度减去第二预设间隙112的厚度,完成后的剖面如图10所示。The first
光刻、腐蚀衬底晶圆101第一表面一侧的第一牺牲层131,腐蚀第一表面一侧第三预设间隙113以外的牺牲层,然后均匀淀积第二牺牲层132,第二牺牲层132均匀覆盖衬底晶圆101两侧的第一表面和第二表面和通孔的内壁,第二牺牲层132的厚度等于第二预设间隙112的厚度,完成后的剖面如图11所示。Photolithography, etch the first
干法刻蚀去除衬底晶圆101第二表面的第一牺牲层131和第二牺牲层132,均匀淀积第二多晶硅层以形成固定层102、支撑梁103和微镜104,第二多晶硅层填充通孔内空间,形成支撑梁103,为了保证完全填充,需采用低压化学气相淀积(Low Pressure ChemicalVapour Deposition,LPCVD)工艺,并且必须在淀积的同时将多晶硅层掺杂为第一掺杂类型(in-situ doping)。完成后的剖面如图12所示。Dry etching removes the first
光刻并腐蚀第一表面一侧的第二多晶硅层,形成微镜104,继续腐蚀去除暴露出的第二牺牲层132,完成后的剖面如图13所示。Photoetching and etching the second polysilicon layer on one side of the first surface to form a
光刻、离子注入并热扩散形成第一驱动电极121和第二驱动电极122,由于微镜104的尺寸厚度远大于离子注入的深度,第一驱动电极121、第二驱动电极122与微镜104实现自对准。完成后的剖面如图14所示。Photolithography, ion implantation and thermal diffusion form the
制作光学结构107、金属引线,腐蚀去除第一牺牲层131和第二牺牲层132释放结构,制成如图1所示的结构,完成制作。Fabricate the
本申请具有如下优点:This application has the following advantages:
微镜104采用垂直于硅片表面的支撑梁103支撑,支撑梁103在垂直方向的倔强系数远大于平面内方向,抵抗垂直方向的静电吸合效应(Pull-in effect)的能力强。并且屏蔽电极123与微镜104始终保持等电位,减小了垂直方向的静电力。因此,可以将第二预设间隙112缩小到纳米量级,来提高横向静电驱动力,从而在保证横向位移的前提下缩小单元尺寸。The
由于第一驱动电极121、第二驱动电极122与屏蔽电极123采用同一层材料制作,可以实现平坦的上表面,上表面的起伏小于10nm。该特点使间隙11可以减小到纳米尺度,来提高横向静电驱动力,从而在保证横向位移的前提下缩小单元尺寸。Since the
采用本申请所述的工艺,可实现埋在圆片内且垂直于圆片表面的支撑梁103,梁的长度不再受单元在面内的边长限制,可以通过增加梁长来减小支撑梁103在水平面内的倔强系数,从而保证横向位移满足应用需求。Using the process described in this application, the
驱动电极与微镜104的自对准工艺减小了工艺误差,可增加电极对的数量。The self-alignment process of the driving electrodes and the
附图说明Description of drawings
为了更清楚地说明本申请实施例中的技术方案,下面将对实施例描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图仅仅是本申请的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他的附图。In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.
图1为本申请一个实施例的微镜结构示意图;Fig. 1 is the micromirror structure schematic diagram of an embodiment of the present application;
图2为本申请一个实施例的微镜结构俯视图;Fig. 2 is the top view of the micromirror structure of an embodiment of the present application;
图3为本申请一个实施例的驱动电极层结构示意图;FIG. 3 is a schematic diagram of a structure of a driving electrode layer according to an embodiment of the present application;
图4为本申请一个实施例的微镜结构透视图;Fig. 4 is the perspective view of the micromirror structure of an embodiment of the present application;
图5为本申请一个实施例的微镜结构示意图;Fig. 5 is the micromirror structure schematic diagram of an embodiment of the present application;
图6为本申请一个实施例的盲孔制作完成后的结构示意图;FIG. 6 is a schematic structural diagram of a blind hole of an embodiment of the present application after fabrication;
图7为本申请一个实施例的第一绝缘层制作完成后的结构示意图;FIG. 7 is a schematic structural view of the first insulating layer of an embodiment of the present application after fabrication;
图8为本申请一个实施例的第二表面腐蚀完成后的结构示意图;Fig. 8 is a schematic structural diagram of an embodiment of the present application after the second surface is corroded;
图9为本申请一个实施例的通孔制作完成后的结构示意图;FIG. 9 is a schematic structural diagram of an embodiment of the present application after the through hole is fabricated;
图10为本申请一个实施例的淀积第一牺牲层完成后的结构示意图;FIG. 10 is a schematic structural diagram of an embodiment of the present application after depositing the first sacrificial layer;
图11为本申请一个实施例的淀积第二牺牲层完成后的结构示意图;FIG. 11 is a schematic structural diagram of an embodiment of the present application after depositing a second sacrificial layer;
图12为本申请一个实施例的多晶硅层沉积完成后的结构示意图;FIG. 12 is a schematic structural diagram of an embodiment of the present application after the polysilicon layer is deposited;
图13为本申请一个实施例的微镜制作完成后的结构示意图;Fig. 13 is the structural schematic diagram after the micromirror of an embodiment of the present application is made;
图14为本申请一个实施例的微镜结构制备完成后的结构示意图;Fig. 14 is a schematic structural diagram of the micromirror structure prepared in one embodiment of the present application;
图15为本申请一个实施例的微镜制作完成后的结构示意图;Fig. 15 is the structural schematic diagram after the micromirror of an embodiment of the present application is made;
图16为本申请一个实施例的驱动电极制作完成后的结构示意图;FIG. 16 is a schematic structural diagram of the driving electrode of an embodiment of the present application after fabrication;
图17为本申请一个实施例的微镜结构制备完成后的结构示意图;Fig. 17 is a schematic structural diagram of the micromirror structure prepared in one embodiment of the present application;
以下对附图作补充说明:The accompanying drawings are supplemented as follows:
101-衬底晶圆;102-固定层;103-支撑梁;104-微镜;105-第一绝缘层;106-第二绝缘层;107-光学结构;108-盲孔;111-第一预设间隙;112-第二预设间隙;113-第三预设间隙;120-驱动电极层;121-第一驱动电极;122-第二驱动电极;123-屏蔽电极;131-第一牺牲层;132-第二牺牲层。101-substrate wafer; 102-fixed layer; 103-support beam; 104-micromirror; 105-first insulating layer; 106-second insulating layer; 107-optical structure; 108-blind hole; 111-first 112-second preset gap; 113-third preset gap; 120-drive electrode layer; 121-first drive electrode; 122-second drive electrode; 123-shield electrode; 131-first sacrifice layer; 132 - second sacrificial layer.
具体实施方式Detailed ways
下面将结合本申请实施例中的附图,对本申请实施例中的技术方案进行清楚、完整地描述。显然,所描述的实施例仅仅是本申请一部分实施例,而不是全部的实施例。基于本申请中的实施例,本领域普通技术人员在没有作出创造性劳动的前提下所获得的所有其他实施例,都属于本申请保护的范围。The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Apparently, the described embodiments are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.
此处所称的“一个实施例”或“实施例”是指可包含于本申请至少一个实现方式中的特定特征、结构或特性。在本申请的描述中,需要理解的是,术语“上”、“下”、“顶”、“底”等指示的方位或位置关系为基于附图所示的方位或位置关系,仅是为了便于描述本申请和简化描述,而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作,因此不能理解为对本申请的限制。此外,术语“第一”、“第二”仅用于描述目的,而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此,限定有“第一”、“第二”的特征可以明示或者隐含的包括一个或者更多个该特征。而且,术语“第一”、“第二”等是用于区别类似的对象,而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换,以便这里描述的本申请的实施例能够以除了在这里图示或描述的那些以外的顺序实施。Reference herein to "one embodiment" or "an embodiment" refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom" etc. is based on the orientation or positional relationship shown in the drawings, and is only for It is convenient to describe the application and simplify the description, but not to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and thus should not be construed as limiting the application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of these features. Also, the terms "first", "second", etc. are used to distinguish similar items and not necessarily to describe a specific order or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein.
实施例一:Embodiment one:
采用P型单晶硅圆片作为衬底晶圆101,并采用如下制作工艺:A P-type monocrystalline silicon wafer is used as the
步骤S1:在P型单晶硅圆片上采用LPCVD制作第二绝缘层106和第一多晶硅层,并对驱动电极层120进行P型掺杂,第一多晶硅层用于形成驱动电极层120。第二绝缘层106采用LPCVD制作的低应力氮化硅。Step S1: Form the second insulating
步骤S2:采用深反应离子刻蚀制作盲孔108,盲孔穿过第二绝缘层106和驱动电极层120并终止在硅圆片内,深宽比控制在25:1以内。Step S2: Deep reactive ion etching is used to form the
步骤S3:采用LPCVD淀积制作第一绝缘层105,第一绝缘层105采用LPCVD制作的低应力氮化硅。Step S3: forming the first insulating
步骤S4:从硅圆片第二表面进行腐蚀,暴露出盲孔108内第一绝缘层105的底部,腐蚀深度近似等于硅圆片的厚度减去盲孔108的深度。Step S4: Etching from the second surface of the silicon wafer to expose the bottom of the first insulating
步骤S5:从硅圆片第二表面进行干法刻蚀,去除盲孔108底部氮化硅绝缘层。Step S5: Perform dry etching from the second surface of the silicon wafer to remove the silicon nitride insulating layer at the bottom of the
步骤S6:均匀淀积第一牺牲层131,第一牺牲层131的厚度等于第一预设间隙111的宽度减去第二预设间隙112的厚度,第一牺牲层131采用LPCVD淀积的TEOS氧化层。Step S6: uniformly depositing the first
步骤S7:光刻、腐蚀衬底晶圆101第一表面一侧的第一牺牲层131,腐蚀去除第一表面一侧第三预设间隙113以外的牺牲层,然后均匀淀积第二牺牲层132,第二牺牲层132的厚度等于第二预设间隙112的厚度,第二牺牲层132采用LPCVD淀积的磷硅玻璃PSG。Step S7: photolithography, etch the first
步骤S8:干法刻蚀去除衬底晶圆101第二表面的第一牺牲层131和第二牺牲层132,采用LPCVD淀积第二多晶硅层,第二多晶硅层采用一层磷重掺杂低应力多晶硅和一层普通低应力多晶硅的复合层,热退火后多晶硅层内可实现均匀的磷掺杂。Step S8: dry etching to remove the first
步骤S9:光刻并腐蚀第一表面一侧的第二多晶硅层,形成微镜104,继续腐蚀去除暴露出的第二牺牲层132。Step S9 : photoetching and etching the second polysilicon layer on the first surface side to form the
步骤S10:光刻、磷离子注入并热扩散形成N型掺杂的第一驱动电极121和第二驱动电极122,由于微镜104的尺寸厚度远大于离子注入的深度,第一驱动电极121、第二驱动电极122与微镜104实现自对准。磷离子注入剂量保证第一驱动电极121和第二驱动电极122反型形成N型掺杂,屏蔽电极123仍为P型掺杂。Step S10: Photolithography, phosphorous ion implantation and thermal diffusion to form N-type doped first driving
步骤S11:制作光学结构107、金属引线,采用氢氟酸蒸汽腐蚀去除第一牺牲层131和第二牺牲层132释放结构,制成如图1所示的结构,完成制作。Step S11: Fabricate the
在微镜工作时,将N型掺杂的微镜与P型掺杂的硅衬底、屏蔽电极连接到地电位,在P型驱动电极上施加负的驱动电压,在实现微镜横向驱动的同时保证驱动电极与屏蔽电极间的PN结反偏。When the micromirror is working, the N-type doped micromirror, the P-type doped silicon substrate, and the shielding electrode are connected to the ground potential, and a negative driving voltage is applied to the P-type driving electrode to realize the lateral drive of the micromirror. At the same time, ensure that the PN junction between the driving electrode and the shielding electrode is reverse-biased.
实施例二:Embodiment two:
实施例二与实施例一的区别是不制作第二绝缘层106和第一多晶硅层。采用P型单晶硅圆片,制作工艺为省略实施例一中的步骤S1,其余步骤均相同,工艺中的区别仅在于:步骤S10改为光刻、磷离子注入并热扩散在P型单晶硅衬底中形成N型掺杂的第一驱动电极121和第二驱动电极122。完成步骤S9后的剖面图如图15所示,完成步骤S10后的剖面图如图16所示,制成的结构剖面图如图17所示。The difference between the second embodiment and the first embodiment is that the second insulating
在微镜工作时,微镜下的P型硅衬底直接用作为屏蔽电极,将N型掺杂的微镜与P型掺杂的硅衬底接地电位,在P型驱动电极上施加负的驱动电压,在实现微镜横向驱动的同时保证驱动电极与硅衬底间的PN结反偏。When the micromirror is working, the P-type silicon substrate under the micromirror is directly used as a shielding electrode, and the N-type doped micromirror and the P-type doped silicon substrate are grounded, and a negative voltage is applied to the P-type driving electrode. The driving voltage ensures the reverse bias of the PN junction between the driving electrode and the silicon substrate while realizing the lateral driving of the micromirror.
以上所述仅为本申请的较佳实施例,并不用以限制本申请,凡在本申请的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本申请的保护范围之内。The above descriptions are only preferred embodiments of the application, and are not intended to limit the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application shall be included in the protection of the application. within range.
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