The controlled HBT structure of operating frequency that is used for the RF field
Technical field
The present invention relates to a kind of semiconductor device and integrated circuit fabrication process, be specifically related to a kind of for controlled heterogenous dual-pole transistor (HeterojunctionBipolar Transistor, the HBT) preparation method of the operating frequency in radio frequency (RF) field.
Background technology
Be illustrated in figure 1 as the structural representation of existing HBT: inject high concentration N-type buried impurity layer 9 at p-type substrate 1 and draw as collector region, the N-type Impurity injection forms N-type collector region (collecter) 3, and shallow-trench isolation (STI) 4 structures are carried out the electricity isolation with the HBT of unit.Growth has P type SiGe epitaxial loayer 7 on the collector region 3, and p-type SiGe epitaxial loayer 7 peripheries have oxidation isolation window mouth (oxide spacer) 5, are emitter region on the P type SiGe epitaxial loayer 7.
The operating frequency of above-mentioned existing HBT device too slowly and not has controllability (shown in Figure 3) with the variation of emitter-collector voltage, and with the variation of emitter-base stage too fast and uncontrollable (shown in Figure 2), so existing HBT device can only be operated under the specific operating frequency usually, and can not regulate operating frequency by applied voltage.
Summary of the invention
Technical problem to be solved by this invention provides a kind of for the controlled HBT structure of the operating frequency in RF field, and it can be regulated operating frequency by applied voltage.
In order to solve above technical problem, the invention provides a kind ofly for the controlled HBT structure of the operating frequency in RF field, comprise a high concentration p type impurity buried regions that between P type substrate and collector region, injects.
The present invention introduces a longitudinal electric field by the injection at the high concentration p type impurity of npn type HBT device collector electrode in device, by collector voltage the control of this electric field has been realized the control of voltage to operating frequency.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.
Fig. 1 is existing HBT structural representation;
Fig. 2 is existing HBT device operating frequency and base-emitter voltage relationship figure;
Fig. 3 is existing HBT device operating frequency and collector to-boase voltage graph of a relation;
Fig. 4 is HBT structural representation of the present invention;
Fig. 5 is HBT device operating frequency of the present invention and collector to-boase voltage graph of a relation.
Reference numeral among the figure is: 1, P type substrate; 2, high concentration p type impurity buried regions; 3, collector region; 4, shallow-trench isolation; 5, oxidation isolation window; 6, high concentration p type impurity buried regions is to the distance of shallow-trench isolation; 7, P type SiGe epitaxial loayer; 8, exhaust line; 9, high concentration N-type buried impurity layer; BP2STI, high concentration p type impurity buried regions arrive the distance of shallow-trench isolation.
Embodiment
As shown in Figure 4, of the present invention is to inject the high concentration p type impurity between the P of existing HBT type substrate 1 and collector region 3 for the controlled HBT structure of the operating frequency in RF field, forms a high concentration p type impurity buried regions 2, exhausts line 8 in collector region 3.
Preferably, this high concentration p type impurity buried regions 2 has the 1e19cm of being not less than
-3Impurity concentration.
Preferably, this high concentration p type impurity buried regions is 600nm~1000nm to the distance 6 of shallow-trench isolation.
Preferably, this high concentration p type impurity buried regions 2 has the thickness of 150nm~200nm.
Of the present inventionly can make by the conventional process of semiconductor applications for the controlled HBT structure of the operating frequency in RF field, manufacture method is as follows:
(1) shallow-trench isolation preparation;
(2) inject high concentration boron ion (this is important step of the present invention) at P type substrate, implanted dopant concentration is 1e19cm
-3, high concentration p type impurity buried regions is 800nm to the distance of shallow-trench isolation, the high concentration p type impurity buried regions thickness of formation is 153nm;
(3) carrying out collector region at high concentration p type impurity buried regions injects;
(4) oxidation isolation window interruption-forming;
(5) SiGe growth;
(6) emitter preparation.
The present invention introduces a longitudinal electric field by the injection at the high concentration p type impurity of npn type HBT device collector electrode in device, by collector voltage the control of this electric field has been realized the control of voltage to operating frequency.As shown in Figure 5, when high concentration p type impurity buried regions was respectively 0.4 μ m, 0.6 μ m and 0.8 μ m to the distance (BP2STI) of shallow-trench isolation, the curve of operating frequency and collector to-boase voltage relation had had controllability between 2V~10V.