Abstract
The present invention relates to vertical integrated, quantized FET with sharp drain and BJT with sharp emitter implemented in one nano-BiCMOS process, using multiple identical single crystalline semiconductor pyramids, placed in-situ directly on the surface of diffusion regions. The devices' gate and base structures are formed at a level of 35-45 nm below the top of the pyramids. The bottom region of the pyramids contains the collector/source structures, while the top region of the pyramids contains the emitter/drain structures. The base structure for BJT is formed by selective epitaxial growth of SiSi.sub.xGe.sub.1-xSi with opposite conductivity type as COR, and interconnected by a horizontal polysilicon grid. The self-aligned gate structure for FET is formed by high dopant implantation of impurity with the same type of conductivity as COR through horizontal gate bridge, which represent a grid of horizontal stacked layers Si.sub.3N.sub.4 high-k insulatorpolysiliconhigh-k insulatorSi.sub.3N.sub.4.
Claims
1. A vertical integrated quantized semiconductor sharp transistor comprising: a silicon substrate of a first conductivity type; a first silicon epitaxial layer of a second conductivity type above the substrate; a second silicon epitaxial layer of a first conductivity type; a diffusion region of a first or second conductivity type, said well, implemented in an epitaxial layer and insulated by SiO.sub.2 regions said shallow tranche insulation (STI), according to the conventional CMOS twin well process; a large diffusion region of a second or first conductivity type, and at least one diffusion region of the opposite conductivity type, said tap implemented separate inside of the well; a plurality of identical semiconductor pyramid structures, placed in-situ directly on the large diffusion region of the well, creating said pyramid texture; wherein the pyramids are obtained by selective epitaxial growth of low dopant Si (100) into vertical oxide cavities, having the first and second conductivity type; a first structure, said base or gate intrinsic structure of a first or second conductivity type formed on the sloped side of the pyramid, coupled together by a horizontal grid of a polysilicon layer, and interconnected by contacts; wherein a polysilicon layer contains silicide and is covered on both sides by a high-k insulator and nitride layers; a second structure, said emitter or drain intrinsic structure of a second or first conductivity type, formed on the top of each pyramid, coupled together by the second poly grid layer with contacts from emitter or drain to the metal 1 layer; a third structure, said collector or source structure of a second or first connectivity type, formed on the bottom region of the pyramids, coupled together by a large diffusion region with contacts from the collector or source to metal 1 layer; a tap connection to the power supply or ground by contacts and metal 1 layer.
2. A BJT base intrinsic structure on the sloped side of the silicon pyramid, placed below the top tip (range 40-50 nm), as claimed in claim 1, comprising: a first epitaxial silicon layer on the surface of the pyramid of a second or first conductivity type (thickness range 0.1-0.2 nm); a second silicon-germanium epitaxial layer of a second or first conductivity type on the first silicon layer (thickness range 5-10 nm); a third epitaxial silicon layer of a second or first conductivity type on the silicon-germanium layer (thickness range 0.2-0.4 nm); a polysilicon layer grid of a second or first conductivity type, formed in result that Si.sub.xGe.sub.1x grows as a crystal on silicon, and as polycrystalline on oxide; a silicide of a second or first conductivity type, for example TiSi.sub.2, layer on the silicon zone and poly-layer; a contacts to the polysilicon layer and the metal layer; ![text missing or illegible when filed]()
3. A FET gate intrinsic structure on the sloped side of the silicon pyramid, placed horizontally on the SiO.sub.2 substrate, below the tips of the pyramids (range 30-40 nm), as claimed in claim 1, comprising: an epitaxial silicon layer of a second or first conductivity type on the surface of the pyramid (thickness range 0.1-0.2 nm); a bottom nitride layer grid (open size about 8080 nm, pitch 120 nm, thickness range 5-20 nm, enclosure of silicon pyramids 5-40 nm, enclosure of quantized transistor area 40-60 nm); a first T-mode deposited high-k insulator grid (open sizeabout 8080 nm, thickness range 2-10 nm), formed directly on thin epitaxial layer on sloped side of pyramid, and on bottom nitride layer grid; a deposited polysilicon layer grid (open sizeabout 8080 nm, thickness range 2-20 nm), placed directly on a first T-mode deposited high-k insulator grid; a second T-mode deposited portion of high-k insulator grid (open sizeabout 8080 nm, thickness range 2-10 nm), placed on the polysilicon grid; a top deposited nitride layer grid (open sizeabout 8080 nm, thickness range 5-20 nm), placed on high-k insulator grid; a gate bridge structure, formed in result of full etch of SiO.sub.2 under the bottom nitride grid; a high doped source and drain regions of pyramids obtained in result of diffusion of a same kind of impurity as pyramids COR; a contact to polysilicon grid and metal 1 layer; ![text missing or illegible when filed]()
4. An emitter or drain intrinsic structure of a second or first conductivity type formed on top of the pyramids, starting at a level of 15-20 nm below of the pyramid tips, as claimed in claim 1, comprising: an epitaxial high dopant growth layer on the open top surface of the pyramid (thickness range 20-30 nm) with a higher concentration of the same dopant materials (range 10-100%) as the pyramid COR; a polysilicon layer grid (open sizeabout 80 nm, thickness range 30-40 nm, enclosure of silicon pyramid 5-20 nm, enclosure of quantized transistor area 50-70 um), formed in result of using chemical vapor deposition, lithography processing, and deposition of silicide (TiSi.sub.2) with the same type of conductivity as the pyramid COR; a contact to polysilicon and metal 1 layer.
5. A n-FET with sharp drain, as claimed in claim 1, comprising: a n type gate structure, n+ type source structure, and a n+ type drain structure; wherein the first conductivity is p type, second conductivity is n type, and a p+ tap is connected to the ground.
6. A p-FET with sharp drain, as claimed in claim 1, comprising: a p type gate structure, p+ type source structure, and a p+ type drain structure; wherein the first conductivity is p type, second conductivity is n type, and a n+ tap is connected to the power supply.
7. A n-p-n BJT with sharp emitter, as claimed in claim 1, comprising: a p type base structure, n+ type collector structure and n+ type emitter structure; wherein the first conductivity is p-type, and the second conductivity is n+ type.
8. A p-n-p BJT with a sharp emitter, as claimed in claim 1, comprising: a n-type base structure, p+ type emitter structure, and p+ type collector structure; wherein the first conductivity is p-type, and the second conductivity is n-type.
9. The method of creation a silicon (111) pyramid structure, as claimed in claim 1 comprising: creation of a Si.sub.3N.sub.4 hard mask on Si (100) substrate, with an array of segments of 6060120 nm, with a 120 nm pitch; deposition of SiO.sub.2 and chemical-mechanical polish and planarization; etching of Si.sub.3N.sub.4; selective epitaxial growth of Si (100) of first and second conductivity types in the opened SiO.sub.2 cavities; wherein the wafer is placed face down in the reactor, parallel to the direction of the gaseous flow of SiCl.sub.4; low dose energy RIE pre clean and sharpening of pyramids is provided.
10. The method related to claims 1 and 3 wherein deposition a high-k insulating layer includes selecting a high-k material from the group of materials consisting of HfO.sub.2, ZrO.sub.2 and HfZrOx.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1. is a cross section diagram and planar view illustrating the embodiment of BICMOS quantized devicesa vertical transistor such as bipolar junction transistor (BJT) or field effect transistor (FET) with sharp emitter or drain.
[0026] FIG. 2.a. is a cross section diagram illustrating an embodiment of a vertical n-p-n structure such as bipolar junction transistor (BJT) or heterojunction transistor (HBT) with sharp emitter.
[0027] FIG. 2.b. is a cross section diagram illustrating an embodiment of a vertical p-n-p BJT with sharp emitter.
[0028] FIG. 2.c. is a cross section diagram illustrating an embodiment of a vertical n-FET with sharp drain.
[0029] FIG. 2.d. is a cross section diagram illustrating an embodiment of a vertical p-FET with sharp drain.
[0030] FIG. 3a. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-d. Particularly on this stage are partial created collector and source structures, and are formed p-type and n-type silicon pyramids for BJT and FET.
[0031] FIG. 3.b. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created thin n-type epitaxial layer for n-type pyramids, collector structure and p-type base structure on level (I) for n-p-n BJT.
[0032] FIG. 3.c. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created thin p-type epitaxial layer for p-type pyramids, collector structure and n-type base structure on level (I) for p-n-p BJT.
[0033] FIG. 3.d. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created on level (II) and (III) horizontal poly structures connected to BJT bases, and gate structures for FET. Also is removed SiO.sub.2 for n-FET, and is created first gate bridge.
[0034] FIG. 3. e. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created gate structures for n-FET and is removed SiO.sub.2 for p-FET second gate bridge.
[0035] FIG. 3.f. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created gate structures for p-FET, and oxidation is provided.
[0036] FIG. 3.g. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created p-type emitter structure for p-n-p BJT and p-type source structure for p-FET.
[0037] FIG. 3.h. is a part of flow diagram illustrating an embodiment of a method of forming a transistor structures such as the structure illustrated in FIG. 2.a-g. On this stage are created n-type emitter structure for n-p-n BJT and n-type source structure for n-FET.
[0038] FIG. 3.i. illustrates created and interconnected n-p-n BJT, p-n-p BJT, n-FET and p-FET transistors with sharp emitter/drain.
[0039] FIG. 4.a. shows a cross-section diagram of prior art applications related to fin textured silicon (100), pencil textured silicon (111), pyramid textured silicon (111), and con textured silicon
[0040] FIG. 4.b. shows the key of prior art applications related to finFET technology, took in consideration as analog for present disclosure.
[0041] FIG. 4.c. shows the perspective view of prior art application related to carbon nano-tubes multi gate FET, took in consideration as prototype for present disclosure.
[0042] FIG. 4.d. shows some basic application related to sharp fluid output and sharp cathode configuration, which allow achieving the same effect for lower pressure/voltage
DETAILED DESCRIPTION OF THE PREFERED EMBODIMENTS
[0043] The embodiments herein will be better understood from the following detailed description that references the drawings, which are not necessarily drawn to scale. In the description of the invention, n, n+, N, N+ and p, p+, P, and P+ are used to define relative dopant types and concentrations. FET is used interchangeably with field-effect transistor, or metal-oxide transistor. BJT is used interchangeably with bipolar junction transistor or bipolar heterojunction transistor. COR is used interchangeably with Composite Object Reference structure. CMP is used interchangeable with Chemical-Mechanical Polishing/Planarization. RIE is used interchangeable with Reactive Ion Etching.
[0044] In reference to the drawings, FIG. 1. shows the general concept of the present invention. A cross section diagram and planar view illustrate a first preferred embodiment of a vertical quantized transistor such as a BJT and FET with a sharp emitter or drain fabricated, utilizing the conventional BiCMOS process, which is adjusted to the implementation of specific quasi-planar structures. It is a portion of a semiconductor chip that includes a monocrystalline, P+ type Si (100) substrate [1], first Si (100) epitaxial layer on the substrate [2], second Si (100) epitaxial layer [3], with N and P wells insulated by SiO.sub.2 regions [7], according to the state-of-the-art shallow trench insulation (STI) process, large sub-collector and sub-source diffusion structures [4] with opposite conductivity types as well, tap diffusion regions inside of the well [5], connection to the source or collector structures [20], base or gate structures [8], base or gate grid [9], emitter or drain structure [10], emitter or drain grid [19], contact [12], metal 1 layer portions [11], and single crystalline silicon (111) pyramids [6], created in SiO.sub.2 cavities by epitaxial growth of Si (100). Pre-cleaning and sharpening is performed, using reactive ion etching (RIE), and the recesses are filled by the epitaxial growth of a low dopant layer of the same conductivity type and dopant level as COR.
[0045] More details relating to the n-p-n BJT is shown in FIG. 2(a), wherein SiO.sub.2 is removed from regions of the n-p-n transistor, and n-type pyramids and collector diffusion regions are highly doped with an n+ type of implant, forming enriched peripheral conductivity of pyramids which in turn minimizes collector resistance. Then, SiO.sub.2 is deposited on level (I) 40-50 nm below the upper tips of the pyramids. After that, the surface of the pyramids [17] is cleaned, using an RIE process. The base structure is formed by the epitaxial growth of p-type SiSiGeSi (100) (Si [14b] 0.1-0.2 nm, SiGe [15b] 5-10 nm, and Si [16b] 0.2-0.4 nm). The base grid is formed by the selective horizontal formation of a polysilicon layer [9a], coated on both sides by an SiO.sub.2 layer [18a], followed by an Si.sub.3N.sub.4 layer [19] (also on both sides). The connection of polysilicon to the base structure is obtained as a result of polysilicon growth of SiO.sub.2 on an insulator and as Si on SiSiGeSi structure. After deposition of the first and second nitride layers and before the emitter structure formation, an RIE pre-clean of the pyramids is performed on levels (I) and (III) respectively in order to remove the nitride layer from the sloped sides of the pyramids before the deposition of a polysilicon layer and a nitride layer on the sloped sides of the pyramids. Then SiO.sub.2 is deposited on level (III) and an n+ type emitter structure [10a] is formed by epitaxial growth of Si (100) on the p-type base structure pyramid (thickness range 20-30 nm) with a higher concentration of the same dopant materials (range 10-100%) as the pyramid COR. Then SiO.sub.2 is deposited on level (IV) forming a polysilicon connection to the emitter [8a]. Connection [12] of polysilicon base [9a] and polysilicon emitter [10a] are obtained by etching SiO.sub.2 and Si.sub.3N.sub.4 and using respectively p-type or n-type silicide layers.
[0046] More details relating to p-n-p BJT are shown in FIG. 2(b). SiO.sub.2 is removed from the p-n-p transistor regions. P-type pyramids and collector diffusion regions are highly doped with a p+ type of implant, forming an enriched peripheral conductivity of pyramids, in turn minimizing collector resistance, and achieving a sharp configuration of collectors. Then, SiO.sub.2 is deposited on level (I), 40-50 nm below the tips of the pyramids, forming an n-type base structure by epitaxial growth of n-type SiSiGeSi (100) layers (Si [14b] 0.1-0.2 nm, SiGe [15b] 5-10 nm, and Si [16b] 0.2-0.4 nm). The base grid is formed by the selective horizontal formation of a polysilicon layer [9a], coated on both sides by an SiO.sub.2 layer [18a], followed by an Si.sub.3N.sub.4 layer [19] (also on both sides).
[0047] Then SiO.sub.2 is deposited on level (III) and p+ type emitter structure [10b] is formed by epitaxial growth of Si (100) on the n-type base structure. SiO.sub.2 is deposited on level (IV), where a polysilicon connection to the emitter [8b] is created. Connection of polysilicon base grid and polysilicon emitter grid are obtained by the etching of SiO.sub.2 and Si.sub.3N.sub.4 and using respective n-type and p-type silicide layers.
[0048] More details, relating to n-FET, are shown in FIG. 2(c), wherein SiO.sub.2 is deposited on level (I) 40-50 nm below the upper tips of the pyramids. The gate structure is formed by selective horizontal deposition of S.sub.3N.sub.4, high-k insulator, polysilicon, high-k insulator and Si.sub.3N.sub.4 layers [19c], [18c], [9c]. After the deposition of the first and second nitride layers, an RIE pre-clean of the pyramids is performed on levels (I) and (III) in order to remove the nitride layer from the sloped sides of the pyramids before the deposition of a first high-k insulator layer, and the nitride and high-k insulator layers on the sloped sides of pyramids, all before the formation of the drain structure. The connection of polysilicon to the gate is obtained as a result of the high-k insulator layer being deposited in T-mode, forming a horizontal thin high-k insulator layer and gate on the sloped sides of the pyramids. The thickness of the polysilicon layer determines the length of gate. The gate structure is formed as a gate bridge with open windows (about 8080 nm), placed on the same coordinates as tap structures in the bottom regions of the pyramids. After that, oxide is removed from all regions of n-FET and the gate bridge serves as a mask for selective implantation of high dopant impurity of the same conductivity as COR in turn creating self-aligned gates.
[0049] More details, relating to p-FET are shown in FIG. 2(d), wherein SiO.sub.2 is deposited on level (I), 40-50 nm below the tips of the pyramids. The gate structure is formed by selective horizontal deposition of S.sub.3N.sub.4, high-k insulator, polysilicon, high-k insulator and Si.sub.3N.sub.4 layers [19d], [18d], [9d]. The process of creating the source structure, the self-aligned gate bridge, and the emitter structure is similar to the previously described n-FET in FIG. 2(c), except the conductivity of the diffusion regions and the conductivity of the epitaxial layer is opposite.
[0050] The fabrication method of the presently preferred embodiments is described below. It should be appreciated however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of semiconductor fabrication contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention. Description of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments of the invention.
[0051] FIG. 3a-i shows the basic fabrication process flow of an n-p-n BJT(a), p-n-p BJT(b), n-FET(c) and p-FET(d) described by the following steps:
[0052] Step 1(FIG. 3a) starts with a P+ type silicon substrate [1], N+ first Si (100) epitaxial layer on the substrate [2], and a second Si (100) epitaxial layer [3], which represent the active area for building BJT and FET with sharp emitter/drain. The active areas are patterned by first depositing of thin oxide and nitride. A photoresist is deposited and patterned on the top of the nitride. This leads to the following consecutive steps: Creation of STI regions [18] using state-of-the-art STI and CMP processing. Creation of N+ wells [3a], [3d], and P+ wells [3b], [3c]. Creation of N+ wells [3a], [3d], and P+ wells [3b], [3c] using a conventional twin well process. Creation of n+ large diffusion regions [4a], [4c], and p+ diffusion regions [4b], [4d] using a conventional BiCMOS process. Creation of p+ tap [5a] for n-FET and n+ tap [5b] for p-FET. Creation of a Si.sub.3N.sub.4 hard mask on Si (100) substrate, with a 6060120 nm segment array, with a 120 nm pitch. Deposition of SiO.sub.2 (thickness of 105-110 nm), CMP, and planarization. Etching of Si.sub.3N.sub.4. Selective epitaxial growth of Si (100) of first and second conductivity types in the opened SiO.sub.2 cavities, wherein the wafer is placed face down in the reactor, parallel to the direction of the gaseous flow of SiCl.sub.4. Low dose energy RIE pre clean and sharpening is provided. Opening n-p-n BJT(a), p-n-p BJT(b), n-FET(c) and p-FET(d) pyramids, followed by a wet etching. SiO.sub.2 deposition.
[0053] Step 2 (FIG. 3b) start with opening (a) and (c) n-type pyramids, pre-clean and an epitaxial deposition of a Si n-type layer (thickness of 0.1-0.2 nm) to fill the recesses on the sloped sides of the pyramids.
[0054] This leads to the following consecutive steps: SiO.sub.2 deposition. Opening n-type pyramids [6] of region n-p-n BJT(a) including n+ diffusion regions [4a]. High level n+ implantation and formation of a sharp collector [17] for n-p-n BJT. SiO.sub.2 deposition on level (I), pre-clean and epitaxial deposition of a p-type base structure SiSiGe'Si (100) layers (Si [14b] 0.1-0.2 nm, SiGe [15b] 5-10 nm, and Si [16b] 0.2-0.4 nm). SiO.sub.2 deposition.
[0055] Step 3 (FIG. 3c) start with opening the regions of p-n-p BJT(b) and p-FET(d). This leads to the following consecutive steps: Pre-clean of p-type pyramids and epitaxial deposition of a Si p-type layer (0.1-0.2 nm) to fill the recesses on the sloped sides of the pyramids. SiO.sub.2 deposition. Opening p-type pyramids [6] of region p-n-p BJT(b) including p+ diffusion regions [4b]. High level p+ implantation and forming a sharp collector for p-n-p BJT. SiO.sub.2 deposition on level (I), pre-clean and epitaxial deposition of a n-type base structure SiSiGeSi (Si [14b] 0.1-0.2 nm, SiGe [15b] 5-10 nm, and Si [16b] 0.2-0.4 nm). SiO.sub.2 deposition.
[0056] Step 4 (FIG. 3d) start with opening all pyramids of regions n-p-n BJT(a), p-n-p BJT(b), n-FET(c) and p-FET(d) on level (II). This leads to the following consecutive steps: Creation of a nitride grid through deposition and patterning, wherein the grid window size is around 8080 nm each. SiO.sub.2 deposition on the top level of the pyramids. Opening n-p-n BJT(a) pyramids on level of nitride grid and RIE pre-cleaning from level (II). Creation of a p-polysilicon layer through deposition and patterning, wherein the window size is around 8080 nm (thickness range 10-20 nm), forming electrode to p-type base with enclosure of COR greater than 20 nm. RIE pre-cleaning from level (III). Creation of a nitride grid through deposition and patterning, wherein the window size is around 8080 nm. RIE pre-cleaning from level (III) and SiO.sub.2 deposition at the top level of the pyramids. Opening p-n-p BJT(b) pyramids at the level of the nitride grid and RIE pre-cleaning from level (II). Creation of a n-polysilicon layer through deposition and patterning, wherein the window size is around 8080 nm (thickness range 10-20 nm), forming electrode to n-type base with enclosure of COR greater than 20 nm. RIE pre-cleaning from level (III). Creation of a second nitride grid through deposition and patterning, wherein the window size is around 8080 nm. RIE pre-cleaning from level (III) and SiO.sub.2 deposition on the top level of the pyramids. Opening n-FET(c) and p-FET(d) pyramids at the level of the nitride grid and RIE pre-cleaning from level (II). Creation of a high-k insulator layer in T-mode through deposition and patterning, wherein the window size is around 8080 nm (thickness range 2-10 nm), forming a gate on the sloped sides of the pyramids, with horizontal enclosure of COR greater than 20 nm. Creation of a polysilicon gate electrode (thickness range 2-20 nm which determines the length of gate) through deposition and patterning, wherein the horizontal enclosure of COR greater than 20 nm. Creation of a second high-k insulator layer in T-mode through deposition and patterning, wherein the window size is around 8080 nm (thickness range 2-10 nm). RIE pre-cleaning from the level (III). Creation of a second nitride grid through deposition and patterning, wherein the window size is around 8080 nm. RIE pre-cleaning from level (III) and SiO.sub.2 deposition on the top level of the pyramids. All SiO.sub.2 removal from n-FET(c) regions and opening of the reinforced n-FET gate bridge, wherein the open window size is around 8080 nm and are placed on same coordinates as p+ taps. High level of n+ implantation and formation of high dopant source and drain structures, wherein the self-aligned gate has a low dopant level. For DRAM structures, the capacitor [22] is created in this step, according to second preferred embodiment of the present invention (FIG. 2e). The capacitor is formed immediately after opening the reinforced n-FET gate bridge by deposition of a high-k insulated layer on an opened source structure (first electrode) and a poly layer (second electrode connected to the tap). The poly grid bridge is used as a mask in lithography processing for opening a high-k insulated layer on the p+ taps and the deposition of a poly layer with the same conductivity type as the p+ tap. The value of the under-bridge capacitor can be adjusted by sizing the area of the horizontal diffusion region of the source. Deposition of a high-k insulating layer and deposition of a high-k capacitor includes selecting a high-k material from the group of materials consisting of HfO.sub.2, ZrO.sub.2 and HfZrOx.
[0057] Step 5 (FIG. 3e) start with removing all SiO.sub.2 from p-FET(d) regions and opening the reinforced p-FET gate bridge, wherein the open window size is around 8080 nm and are placed on same coordinates as n+ taps. High level of p+ implantation is provided for formation of high dopant source and drain structures; wherein a self-aligned gate has a low dopant level.
[0058] Step 6 (FIG. 3f) start with SiO.sub.2 deposition on the upper level of the pyramids for p-FET(d) regions. On this step the collector and base structures for BJT are done. Also the creation of source and gate structures for FET is now completed.
[0059] Step 7 (FIG. 3g) start with opening regions p-n-p BJT(b) and p-FET(d) on level (III). RIE pre-cleaning of opened parts of COR is provided, and epitaxial silicon p+ layer is grown for creation of emitter structures for p-n-p BJT and source structures for p-FET. The concentration of p+ dopant is 10-100% higher in comparison to the concentration of the collector/source structures.
[0060] Step 8 (FIG. 3h) start with opening regions n-p-n BJT(a) and n-FET(c) on level (III). RIE pre-cleaning of opened parts of COR is provided, and epitaxial silicon n+ layer is grown for the creation of emitter structures for n-p-n BJT and source structures for n-FET. The concentration of n+ dopant is 10-100% higher in comparison to the concentration of the collector/source structures.
[0061] Step 9 (FIG. 3i) start with opening regions n-p-n BJT(a) and n-FET(c) on level (IV). This leads to the following consecutive steps: Deposition of an n-type polysilicon layer. Patterning of emitter grid for n-p-n BJT and similar drain grid for n-FET. SiO.sub.2 deposition at a thickness of 10-50 nm on the upper level of the pyramids. Opening regions p-n-p BJT (b) and p-FET(d) on level (IV). Deposition of a p-type polysilicon layer. Patterning of polysilicon emitter grid for p-n-p BJT and similar drain grid for p-FET. SiO.sub.2 deposition at a thickness of 10-50 nm in the upper level of the pyramids.
