第26卷第7期 半导体学报 Vol.26 No.7 2005年7月 CHINESE JOURNAL OF SEMICONDUCTORS July.2005 Patterned Dual pn Junctions Restraining Substrate Loss of an On-Chip Inductor* Jian Hongyan,Tang Jue,Tang Zhangwen,He Jie,and Min Hao (State Key Laboratory of ASIC &System,Fudan University,Shanghai 200433,China) Abstract:Dual pn junctions in lateral and vertical directions are formed by diffusing the p+on the patterned n-well in standard CMOS technology,which are inserted under the inductor in order to reduce the currents in the substrate induced by the electromagnetic field from the inductor.The thickness of high resistance is not equivalent to the width of the depletion region of the vertical pn junctions,but the depth of the bottom pn junction in the substrate are both proposed and validated.For the first time,through the grounded p+-diffusion layer shielding the substrate from the electric field of the inductor,the width of the depletion regions of the lateral and vertical pn junctions are changed by increasing the voltage applied to the n-wells.The quality factor is improved or reduced with the thickness of high re- sistance by 19%.This phenomenon validates the theory that the pn junction substrate isolation can reduce the loss caused by the currents in the substrate induced by the electromagnetic field from the inductor. Key words:on-chip inductor;patterned dual pn junctions;eddy current;substrate loss EEACC:2140;2530B;2550F CLC number:TM55 Document code:A Article ID:0253-4177(2005)07-1328-06 the resistance of the substratel3.4]can reduce the 1 Introduction eddy currents in the substrate and increase Q. These methods are not standard technology.The Monolithic inductors are important compo-inductor designers aim at realizing a substantially nents in highly integrated radio frequency circuits greater quality factor at circuit operation frequency for wireless communication systems such as a low-without altering the fabrication process,through noise amplifier,a voltage-controlled oscillator,and such methods as using a symmetric inductor that is an impedance matching network.However,on-chip excited differentially[5].Several papers[6-8]have re- inductors have a low quality factor (Q)due to met-ported the singe pn junction substrate isolation, al ohmic loss and conductive silicon substrate loss.however,dual pn junction substrate isolation struc- Many researchers have found several methods to tures without altering the fabrication process have improve the Q of on-chip inductor1]. not been reported and the reasons this structure The use of a patterned ground shield (PGS)[2] can reduce the substrate loss have not been reliably between the inductor metal trace and substrate in- validated by tape-out experiments.The eddy cur- creases Q by reducing the loss of electric energy rent would be formed in an n-well that is designed due to the current induced in a silicon substrate, as a whole layer6,which is larger than the sub- while at the same time not reducing the eddy cur-strate because the resistance of the n-well is less rent,which can significantly reduce Q.Increasing than that of the substrate. Project supported by the Shanghai Science 8.Technology Committee(No.037062019)and the Shanghai Applied Material Founds(No.0425) Jian Hongyan male,PhD candidate.His interested research directions include on-chip inductor and antenna optimization,RF circuits design such as LNA,mixer,VCO,and Antenna design for RFID.Email:hyjian@fudan.edu.cn Received 9 December 2004,revised manuscript received 24 January 2005 ©2005 Chinese Institute of Electronics第B_卷 第M期 BWWV年M月 半 导 体 学 报 58JNE1EYRbPN!?RF1EDJ5RNUb5QRP1 H(#cB_ N(cM Y2#6!BWWV #+.(@;%’72""(.’;,G6’4;14&)34&$1%$;)%;r Q;%4)(#(365(00$’’;;"N(cWZMW_BWAS#&),’4;14&)34&$!""#$;,D&’;.$&#F(2),7"N(cWXBV# Y$&)8()36&) 0&#;!+4U%&),$,&’;c8$7$)’;.;7’;,.;7;&.%4,$.;%’$()7$)%#2,;()[%4$"$),2%’(.&),&)’;))&("’$0$:&’$()!PF%$.%2$’7,;7$3) 72%4&7?N!!0$/;.!H5R!&),!)’;))&,;7$3)*(.PFJUcE0&$#$46@$&)"*2,&)c;,2c%) P;%;$O;,SU;%;0G;.BWWX!.;O$7;,0&)27%.$"’.;%;$O;,BXY&)2&.6BWWV #BWWV54$);7;J)7’$’2’;(*E#;%’.()$%7 BC??>@H>L$<C:DH3<HN?J9HA4>A?@CJHJHR2<KA?@C?>59AA 9MCH%HV0IJD’HL<N?9@# Y$&)8()36&)!Q&)3Y2;!Q&)3L4&)3T;)!8;Y$;!&),D$)8&( ";M#M*B*41#A’P#M’P4’=H;Q+ _ ;4:M*@!6"0#$R$-Y*P:-M4!;)#$%)#- BWWXZZ!+)-$## "KA?@CN?$U2&#")@2)%’$()7$)#&’;.&#&),O;.’$%&#,$.;%’$()7&.;*(.0;,G6,$**27$)3’4;"k ()’4;"&’’;.);,)[T;## $)7’&),&.,5DR1’;%4)(#(36!T4$%4&.;$)7;.’;,2),;.’4;$),2%’(.$)(.,;.’(.;,2%;’4;%2..;)’7$)’4;72G7’.&’; $),2%;,G6’4;;#;%’.(0&3);’$%*$;#,*.(0’4;$),2%’(.cQ4;’4$%^);77(*4$34.;7$7’&)%;$7)(’;]2$O&#;)’’(’4;T$,’4 (*’4;,;"#;’$().;3$()(*’4;O;.’$%&#")@2)%’$()7!G2’’4;,;"’4(*’4;G(’’(0")@2)%’$()$)’4;72G7’.&’;&.;G(’4 ".("(7;,&),O&#$,&’;,cF(.’4;*$.7’’$0;!’4.(234’4;3.(2),;,"k [,$**27$()#&6;.74$;#,$)3’4;72G7’.&’;*.(0’4; ;#;%’.$%*$;#,(*’4;$),2%’(.!’4;T$,’4(*’4;,;"#;’$().;3$()7(*’4;#&’;.&#&),O;.’$%&#")@2)%’$()7&.;%4&)3;,G6 $)%.;&7$)3’4;O(#’&3;&""#$;,’(’4;)[T;##7cQ4;]2&#$’6*&%’(.$7$0".(O;,(..;,2%;,T$’4’4;’4$%^);77(*4$34.;[ 7$7’&)%;G6ASgcQ4$7"4;)(0;)()O&#$,&’;7’4;’4;(.6’4&’’4;")@2)%’$()72G7’.&’;$7(#&’$()%&).;,2%;’4;#(77 %&27;,G6’4;%2..;)’7$)’4;72G7’.&’;$),2%;,G6’4;;#;%’.(0&3);’$%*$;#,*.(0’4;$),2%’(.c S>=T9@LA$()[%4$"$),2%’(.%"&’’;.);,,2&#")@2)%’$()7%;,,6%2..;)’%72G7’.&’;#(77 **"00$BAXW%BVZWI%BVVWF 050H<QK>@$QDVV $9N<Q>H?N9L>$! 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