US8558330 (1060168), страница 4
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12 illustrates a cross sectional vieW 1200 of anThe metalliZation layers are con?gured to connect theembodiment of a metalliZation layer formation corresponding to step 518. As illustrated in FIG. 12, the metalliZationpieZoresistor to an analog to digital converting element(s).At step 520, a passivation layer is formed above the metalliZation layer. In an embodiment, the passivation layer comprises an oxide/ glass and/or silicon nitride layer formed overthe surface of the substrate using a physical vapor deposition,layers 118 are formed to be partially Within an interlevel30118 comprise a Ti or TiN plug in contact With the one or morefor example.At step 522, the protective layer is selectively removedfrom the backside of the substrate to form an opening. In andielectric (ILD) layer 114 located on the top surface 122 ofthe substrate 102.
In an embodiment, the metalliZation layersshalloW p-Wells 108 Within the deep n-Well 104. The metalliZation layers 118 may further comprise copper and/or alu35minum Wires extending perpendicular the plug to provideembodiment, the protective layer is removed using a photolateral connections to the pieZoresistor.lithography and etch process, in Which a photoresist materialis formed on selective parts of the protective layer and thelayer is etched in the open parts of the photoresist material.At step 524, the substrate is subjected to an electrochemiembodiment of a passivation layer being formed, Which corresponds to step 522.
As illustrated in FIG. 13, the passivationlayer 116 encloses the semiconductor substrate 102.FIG. 13 illustrates a cross sectional vieW 1300 of an40cally controlled etching (ECE) process.Some embodiments of an exemplary semiconductor substrate, Whereon such a methodology 500 is implemented, areillustrated in cross-sectional vieWs of FIGS. 6-15. It Will beappreciated that although FIGS. 6-15 are described in relationto the formation of MEMs pressure sensor comprising havingFIG.
14 illustrates a cross sectional vieW 1400 of an45certain doping types, these doping types are not limiting andmay vary in alternative embodiments.FIG. 6 illustrates a cross sectional vieW of an embodimentof a semiconductor substrate corresponding to the substrateof step 502. For illustration, the substrate 102 in FIG. 650potentiostat 1404. The reference electrode 1410 is con?guredto adjust the voltage betWeen the Wafer holder 1408 and thecomprises a non-epitaxial, p-type silicon substrate.FIG. 7 illustrates a cross sectional vieW 700 of an embodiment of an implantation 704 provided to the semiconductorsubstrate 102, Which corresponds to the implantation of step506.
The implantation 704 provides a desired n-type implantcounter electrode 1412.55are not covered by a ?rst masking layer 702. The implantation60so that the etchant 1406 performs a normal anisotropic etchthrough the substrate 102 until it reaches the PN junction 120.Then, because the reverse-biased diode has been etched aWay,ment of a drive in of the implanted n-type dopants corresponding to the drive in of step 508.
The drive in comprisesmally excite the n-type dopants in the shalloW implant regionthe p-type substrate 102, acts as a reverse-biased diode preventing the etchant 1406 from being exposed to any current,strate 102.FIG. 8 illustrates a cross sectional vieW 800 of an embodiexposing the Wafer to a high temperature 802, so as to therDuring etching, the potentiostat 1404 is con?gured toapply a controlled bias betWeen the deep n-Well 104 and thebath 1402 of etchant, causing the etchant 1406 to etch thebackside 124 of the semiconductor substrate 102. A PNjunction 120, located at the intersection of the deep n-Well 104 anddose into one or more regions of the p-type substrate 102 that704 results in the desired n-type implant dose being providedWithin a relatively shalloW implant region 706 having a highn-type dopant concentration to a ?rst depth Within the subembodiment of an ECE etchant bath corresponding to step524. As illustrated in FIG.
14 the substrate 102 is immersed ina bath 1402 ofetchant (e.g., a KOH bath). An opening 1405 inthe protective layers 1102 de?nes an area in Which a cavity isto be formed in the substrate 102. A Wafer holder 1408,connected to a potentiostat 1404, is con?gured to protect thetop surface 122 of the substrate 102 from the etchant 1406 andto provide an electrical contact to the deep n-Well 104. Acounter electrode 1412 and a reference electrode 1410,located Within the etchant bath 1402, are also connected to the65the etchant 1406 (e.g., KOH) is exposed to the applied bias,and a reaction forms a thin layer of silicon dioxide that stopsthe etch.US 8,558,330 B29102.
The method of claim 1, Wherein the deep Well comprisesa gradient doping pro?le extending perpendicular from a topsurface of the semiconductor substrate through the deep Well.3. The method of claim 1, Wherein complementary metaloxide-semiconductor (CMOS) components are formedFIG. 15 illustrates a cross sectional vieW 1500 of anembodiment of a MEMs pressure sensor formed by method500. As illustrated in FIG. 15, the resulting semiconductorsubstrate 102 comprises a cavity 110 Within the backside 124of the substrate that is abuts the deep n-Well 104.
In anembodiment in Which the silicon Wafer comprises a <l00>Within a ?rst region of the semiconductor substrate having ann-type material and Within an adjacent second region of thesemiconductor substrate having a p-type material.4. The method of claim 1, Wherein the ?rst doping typecomprises a p-doping to result in a p-type semiconductorsubstrate and Wherein the second doping type comprises ann-type doping to result in a deep n-Well.5. The method of claim 2, Wherein the gradient dopingcrystal orientation, the cavity 110 comprises steep sideWallangles (e.g., 54.7° angle With the backside surface) sincepotassium hydroxide (KOH) displays an etch rate selectivitythat is higher in a <l00> crystal direction than in a <lll>crystal direction.
It Will be appreciated that the siZe of thecavity 110 may be adjusted by varying the depth of the deepn-Well (and therefore the depth of the PN junction Within thesubstrate) formed at steps 504-508.It Will be appreciated that While reference is made throughpro?le comprises a dopant concentration that is inverselyout this document to exemplary structures in discussingaspects of methodologies described herein , those methodologies are not to be limited by the corresponding structurespresented.
For example, the methodologies set forth in FIG.15 are not limited to the structure presented in FIGS. 6-15.Rather, the methodologies and structures are to be consideredindependent of one another and able to stand alone and be20comprises:implanting an n-type dopant into the p-type semiconductorsubstrate; andpracticed Without regard to any of the particular aspectsdepicted in the Pigs. Additionally, layers described herein canbe formed in any suitable manner, such as With spin on,proportional to the distance from the top surface of the semiconductor substrate.6.
The method of claim 4, Wherein the ECE process stops ata PN junction formed betWeen the semiconductor substrateand the deep n-Well.7. The method of claim 4, Wherein forming the deep Wellexposing the semiconductor substrate to an elevated tem25sputtering, groWth and/or deposition techniques, etc.perature to drive the n-type dopant to a greater depthWithin the semiconductor substrate, thereby forming thedeep n-Well.Also, equivalent alterations and/or modi?cations mayoccur to one of ordinary skill in the art based upon a reading8.
The method of claim 6, Wherein the PN junction has aand/ or understanding of the speci?cation and annexed draWings. The disclosure herein includes all such modi?cationsand alterations and is generally not intended to be limiteddepth that is determined prior to forming the deep Wellthrough predictive simulations of a gradient doping pro?leWithin the deep Well.9. The method of claim 7, Wherein the n-type dopant is30thereby.
For example, although the ?gures provided hereinare illustrated and described to have a particular doping type,implanted into the semiconductor substrate at a dose ion ait Will be appreciated that alternative doping types may berange of approximately 1012 cm'3 to approximately 1017cm_3.utiliZed as Will be appreciated by one of ordinary skill in the3510. The method of claim 7, Wherein the n-type dopant isdriven into the semiconductor substrate by exposing the subart.In addition, While a particular feature or aspect may havebeen disclosed With respect to one of several implementations, such feature or aspect may be combined With one ormore other features and/ or aspects of other implementationsas may be desired.
Furthermore, to the extent that the termsstrate to a temperature in a range of approximately 11000 C.to approximately 1200° C. for approximately 300 minutes to40“includes”, “having”, “has”, “With”, and/or variants thereofapproximately 400 minutes.11. A micro-electro mechanical system (MEMs) pressuresensor, comprising:are used herein, such terms are intended to be inclusive ina semiconductor substrate having a ?rst doping type;meaningilike “comprising.” Also, “exemplary” is merelya deep Well located Within a ?rst side of the substrate to ameant to mean an example, rather than the best. It is also to be45herein are illustrated With particular dimensions and/or orientations relative to one another for purposes of simplicityand ease of understanding, and that the actual dimensionsand/ or orientations may differ from that illustrated herein.a cavity disposed Within a second side of the substrate at aposition opposing the deep Well, such that the deep Wellabuts the cavity;50What is claimed is:1.
A method of micro-electro mechanical system (MEMs)doping pro?le is inversely proportional to the distance from55substrate having a ?rst doping type, Wherein the deep13. The MEMs pressure sensor of claim 11, further comone or more shalloW Wells located Within the deep Well andcon?gured to operate as diffusion resistors, Wherein the60deep Well; andselectively etching a second side of the semiconductorsubstrate by performing an electrochemically controlledetching (ECE) process to form a cavity abutting the deepWell, resulting in a diaphragm structure that operates asa pieZoresistor that is con?gured to measure pressureWithin the cavity.the top surface of the substrate.prising:Well has a second doping type;forming one or more shalloW Wells having the ?rst dopingtype Within the deep Well, Wherein the one or moreshalloW Wells operate as resistive elements Within theWherein the cavity forms a pliable diaphragm Within thesubstrate having a thickness that is de?ned by the depthof the deep Well.12.
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