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89:) was favorable. But the conductivity of the poly-silicon layer is very low and because of this low conductivity, the charge accumulation is low, leading to a delay in channel formation and thus unwanted delays in circuits. The poly layer is doped with N-type or P-type impurity to make it behave like a perfect conductor and reduce the delay.
146:, the electrons move closer toward the gate terminal but due to the open circuit configuration they don't start to flow. As a result of the separation of charges a depletion region is formed on the polysilicon-oxide interface, which has a direct effect on the channel formation in
414:
H. P. Tuinhout, A. H. Montree, J. Schmitz and P. A. Stolk, Effects of gate depletion and boron penetration on matching of deep submicron CMOS transistors, IEEE International
Electron Device Meeting, Technical Digest pp. 631-634,
268:
to occur. So the effect with doped poly is an undesired reduction of threshold voltage that wasn't taken into account during circuit simulation. In order to avoid this kind of variation in
206:). Polysilicon depletion can vary laterally across a transistor depending on the fabrication process, which can lead to significant transistor variability in certain transistor dimensions.
501:
425:
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366:
Rios, R.; Arora, N.D. (1994). "Modeling the polysilicon depletion effect and its impact on submicrometer CMOS circuit performance".
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has released a press-kit regarding their fabrication procedures of different nodes, which showed the use of Metal gate technology.
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575:
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Hobbs, C.C.; Fonseca, L. R. C.; Knizhnik, A. (2004). "Fermi-level pinning at the polysilicon/metal oxide interface-Part I".
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an inversion layer is formed, which can be seen in the figure 1(b) where the inversion channel is formed of acceptor ions (N
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In an NMOS with n+ Polysilicon gate, the poly depletion effect aids in the channel formation by the combined effect of the
426:"ARM, IBM, Samsung, GLOBALFOUNDRIES and Synopsys Announce Delivery of 32/28nm HKMG Vertically Optimized Design Platform"
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Doped polysilicon was preferred earlier as gate material in MOS devices. Polysilicons were used as their
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or metal, previously polysilicon was chosen over metal because the interfacing between polysilicon and
50:, also called polysilicon, is a material consisting of small silicon crystals. The latter differs from
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Rios, R.; Arora, N.D. (1994). "An analytic polysilicon depletion effect model for MOSFETs".
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poly gates are being replaced by metal gates. The following technology is known as
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technology. Also at the interface with gate dielectric, Polysilicon forms an SiO
75:
59:
33:
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185:) on the polysilicon enhances the Formation of the inversion channel and when
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Proceedings
International Symposium: VLSI Technology Systems and Applications
138:
are scattered throughout the structure because of the absence of an external
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as gate material is observed, leading to unpredicted behavior of the
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Variation of threshold voltage in polycrystalline silicon materials
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395:"Impact of polysilicon depletion in thin oxide MOS technology"
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For the above reason as the devices go down on the scaling
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field at gate terminal. Basically the accumulation of the
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matched with the Si substrate (which results in the low
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layer. Moreover, there remains a high probability for
241:). Metal gates were re-introduced at the time when SiO
24:is the phenomenon in which unwanted variation of
482:(Press release). Intel Technology. Nov 11, 2011
66:, used for thin film devices and solar cells.
8:
393:Schuegraf, K.F.; King, C.C.; Hu, C. (1993).
502:"Gate Dielectric Scaling for CMOS: from SiO
44:(HKMG) were introduced to solve the issue.
480:"From Sand to Silicon: The Making of Chip"
279:, at present metal gate is preferred over
134:transistor it is observed that the free
321:
309:Fabrication of microprocessor by intel
531:IEEE Transactions on Electron Devices
368:IEEE Transactions on Electron Devices
7:
93:Doped polysilicon gate disadvantages
14:
511:(Press release). Intel Technology
256:as gate oxide in the mainstream
299:Drain-induced barrier lowering
1:
506:/PolySi to High-K/Metal-Gate"
169:) and the externally applied
42:High-k Dielectric Metal Gates
500:Chau, Robert (Nov 6, 2003).
332:IEEE Electron Device Letters
222:(HKMG) integration. In 2011
220:High-k Dielectric Metal Gate
40:. Because of this variation
22:Polysilicon depletion effect
121:n+ = Highly doped N region
74:The gate contact may be of
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210:Metal gates re-introduced
56:semiconductor electronics
581:Semiconductor technology
543:10.1109/TED.2004.829513
48:Polycrystalline silicon
248:are being replaced by
165:field of donor ions (N
158:
102:
576:Semiconductor devices
156:
100:
52:mocrystalline silicon
70:Gate material choice
266:Fermi level pinning
119:= Threshold Voltage
455:"Global Foundries"
250:high-k dielectrics
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103:
38:electronic circuit
430:news.synopsys.com
404:. pp. 86–90.
380:10.1109/16.381991
345:10.1109/55.285407
235:threshold voltage
204:minority carriers
136:majority carriers
64:amorphous silicon
26:threshold voltage
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111:= Gate Voltage
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32:devices using
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571:Transistors
281:Polysilicon
246:dielectrics
157:Figure 1(b)
144:figure 1(b)
101:Figure 1(a)
76:polysilicon
62:, and from
60:solar cells
34:polysilicon
565:Categories
515:2013-06-08
486:2013-06-08
465:2012-03-28
440:2022-05-04
316:References
80:gate oxide
54:used for
551:45952996
287:See also
586:MOSFETs
353:9878129
275:of the
148:MOSFETs
28:of the
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277:MOSFET
239:MOSFET
192:> V
30:MOSFET
547:S2CID
415:1997.
398:(PDF)
349:S2CID
252:like
224:Intel
175:(+)ve
171:(+)ve
163:(+)ve
258:CMOS
179:ions
131:nMOS
58:and
539:doi
376:doi
341:doi
237:of
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128:an
124:In
84:SiO
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270:v
262:x
243:2
200:A
188:V
183:D
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