US8558330 (1060168), страница 3
Текст из файла (страница 3)
In an embodiment, the ?rst masking layer comprises a patterned photoresist layer. The patterned photoresistlayer may be formed on the surface of the substrate by Way ofa spin coating photoresist onto the substrate. The spin coatedphotoresist is then patterned by selective exposure to a lightsource (e.g., UV light) and subsequently developed.At step 506, a deep Well implant is performed. The deepWell implant may comprise the implantation of a p-typesiZe and also alloWs the resistive signal to be processed inclose proximity to the MEMs pressure sensor.FIG.
4 illustrates a cross sectional vieW of an embodimentof a monolithic MEMs pressure sensor 400. In some otherapproaches, in Which MEMs pressure sensing devices comprise an epitaxial layer having a ?rst doping type (e.g.,dopant (e.g., boron, gallium, etc.) or an n-type dopant (e.g.,phosphorus, arsenic, etc.) into the semiconductor substrate.n-type), a CMOS component can only be fabricated in anenvironment having the ?rst doping type, unless an extra Wellimplantation process is added. HoWever, the use of deepThe dopants are implanted at a dopant concentration that isWell(s) to form a MEMs pressure sensor diaphragm in accorbias diode, Which acts to control an etching depth (e.
g., at step524). In an embodiment, an n-type dopant is implanted into ap-type substrate at a dose of approximately 1012 cm-3 todance With various embodiments of the disclosure alloWs forCMOS components to be selectively fabricated Within eitheran environment having a ?rst doping type a (e.g., n-typematerial) or Within an environment having a second dopingsuf?ciently high to form a PN junction that acts as a reverse20approximately 1017 cm_3. In another embodiment, pho sphorus ions are implanted into the p-type substrate at a dose ofapproximately 1014 cm'3 to approximately 5><l0l7 cm '3 . Intype (e.g., a p-type material). This enables CMOS bulk isolation Within the monolithic MEMs sensor for both p-typeand/ or n-type metal oxide semiconductor ?eld effect transis25at step 504.
In another embodiment, the deep Well implanttors (MOSFETs).may comprise a blanket implant performed over the entiresemiconductor substrate (e.g., over an unmasked substrate).For example, in an embodiment, a ?rst region 402 of substrate 102 comprises a p-type material in Which CMOS components 404 are located and a second, adjacent region 406 ofthe substrate comprises a n-type material in Which CMOScomponents 408 are located. In an embodiment, the CMOScomponents 404 Within the ?rst region 402 comprise one ormore PMOS transistors having n-type shalloW Wells Withinthe p-type semiconductor substrate 102. In an embodiment,the CMOS components 408 Within the second region 4063035deep Wells 104 Within the substrate 102 alloWs bulk isolationexemplary method 500 for forming a MEMs pressure sensordevice. While method 500 is illustrated and described beloWas a series of acts or events, it Will be appreciated that the4045varying deep Well depths may be achieved.
In an embodiin different orders and/or concurrently With other acts orevents apart from those illustrated and/or described herein. Inment, predictive simulations executed on a computer may beperformed prior to implantation at step 506 and drive in at step50508. The predictive simulations can be used to determine aPN junction depth and doping pro?le. Such simulationsenable a precise PN junction depth and doping pro?le toone or more aspects or embodiments of the descriptionherein. Further, one or more of the acts depicted herein maybe carried out in one or more separate acts and/ or phases.At step 502, a semiconductor substrate is provided. In anembodiment, the semiconductor substrate comprises a siliconstarting material, such as a single-crystal silicon With a <1 00>orientation, Which has an n-type or p-type dopant concentration.
In another embodiment, the semiconductor substratebetWeen approximately 7 microns and approximately 11microns by exposing the substrate to a temperature of about1100-12000 C. for about 300-400 minutes. Such a depthprovides for a su?icient elasticity to the MEMs pressuresensor diaphragm. Once the deep Well implant is driven intothe substrate the masking oxide formed at step 504 isremoved.By changing the temperature and length of the drive in,illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occuraddition, not all illustrated acts may be required to implementAt step 508, the deep Well implant is driven into the substrate.
Driving the deep Well implant into the substrate comprises diffusing the dopants introduced at step 506 to a desireddepth Within the substrate. In an embodiment, the deep Wellimplant is driven into the substrate by exposing the substrateto an elevated temperature. The deep Well implant can bedriven into the substrate to a various depths depending on thetemperature and time of the drive in. In some embodiments,the implanted ions are driven into the substrate to a depth ofcomprise one or more NMOS transistors having p-type shalloW Wells Within the deep n-Well 104.
Therefore, the use offor both NMOS and PMOS devices Within a same substrate102.FIG. 5 illustrates a How diagram of an embodiment of anan embodiment, the deep Well implant may be selectivelyperformed Within areas of the substrate that Were not maskedoptimiZe performance of the MEMs pressure sensor.Once the deep Well has been formed Within the substrate, a55MEMs pressure sensor device may be formed Within thesubstrate, at step 510.
The MEMs pressure sensor Will have adiaphragm With a thickness that is de?ned by the depth of thedeep Well implant. Steps 512 -524 illustrate an exemplarycomprises a non-epitaxial, double side polished p-type silimethod for forming a MEMs pressure sensor Within a substrate enables the substrate to comprise regions having p-typestrate having a deep Well formed therein. In some embodiments, alternative steps for forming a MEMs pressure sensormay be used, such that illustrated steps 512-524 are not performed and are therefore illustratively shoWn in dashedboxes.At step 512, the substrate is masked and a sensor implant isperformed.
In an embodiment, the substrate is masked by amaterial and n-type material. This alloWs for CMOS composecond masking layer including a patterned photoresist layer.con substrate, not having an epitaxial layer groWn on thesurface of the substrate.In an embodiment, the semiconductor substrate is selectively masked, at step 504. In some embodiments, step 504 isnot performed, and is therefore illustratively shoWn in adashed box. Selective masking of the semiconductor sub6065US 8,558,330 B278Once the substrate is masked, a sensor implantation is per706 in FIG. 7 and cause them to diffuse to a greater depthformed. The sensor implantation comprises a doping type thatis the same as that of the substrate (e. g., p-type dopant Withinan n-type environment), and Which has a higher concentrationof about 1018, for example.
The sensor implants form a resisWithin the p-type substrate 102. The drive in results in a deepWell 104 having a high dopant concentration that extendsWithin the substrate to a second depth greater than the ?rstdepth.tive shalloW Well Within the deep Well that operates as aFIG. 9 illustrates a cross sectional vieW 900 of an embodipieZoresistive element. The implants are formed into the deepWell at openings in the masking layer.At step 514, the substrate is again masked and a shalloWimplantation is performed.
In an embodiment, the substrate ismasked by a third masking layer including a patterned photoresist layer, for example. Once the substrate is masked ament of a sensor implant corresponding to the sensor implantof step 512. As illustrated in FIG. 9, a second masking layer902 is formed above the substrate to selectively mask the deepn-Well 104. The senor implants 904 are introduced into thedeep Well at a high concentration of a p-type dopant to formone or more shalloW Wells 106.high concentration implantation is performed to implantdopants into the deep Well at openings in the third maskingFIG. 10 illustrates a cross sectional vieW 1000 of anembodiment of a Well contact implant corresponding to Wellcontact implant of step 514.
As illustrated in FIG. 10, a thirdmasking layer 1002 is formed above the substrate to seleclayer. In some embodiments, the implantation comprises adoping type that is the same as that of the sensor implant, butWhich has a higher concentration greater than about 101 8, forexample. The implantation forms Well contacts, Whichimprove the connection betWeen the resistive shalloW Wellsand metalliZation layers, thereby alloWing signals from sentively mask the deep Well 104. The substrate contact implantation 1004 implants a high concentration of a p-type dopantinto the deep Well to form one or more substrate contacts20sor resistive shalloW Wells to be picked up.At step 516, one or more protective layers are formed onFIG.
11 illustrates a cross sectional vieW 1100 of anthe backside of the substrate. The protective layer may comembodiment of the formation of one or more protective layers1102 on a backside 124 of the semiconductor substrate 102prise a SiO2 layer formed by physical vapor deposition, in anembodiment.1006. The shalloW Wells 106 and the Well contacts 108 mayoverlap each other in some embodiments.25corresponding to step 516.At step 518, one or more metalliZation layers are formed.FIG.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
