CN1953147A - Manufacturing method of high frequency transistor with self-aligned dense boron base - Google Patents

Abstract

The invention relates to a method for producing high-frequency transistor via self-align dense boron base area. Wherein, it comprises that after etching multi-crystal emission area, using the photo resist of multi-crystal layer as mask to pour in dense boron; the active area has dense boron area except from the thin base area under the emission area protected by photo resist; the area of multi-crystal layer is same as the area of thin base area. The invention has the advantages that since it reduces the resistance of base area, and fixes the self aim of dense base area by controlling the width of multi-crystal emission area, to reduce processes and reduce 1/7 cost; and it controls the width of thin base area by setting the width of multi-crystal layer, to avoid sheathing error, reduce the resistance of base area, and improve the high-frequency property, as characteristic frequency at f<SUB>T</SUB>.

Description

Adopt the manufacture method of the high frequency transistor of autoregistration dense boron base

Technical field

The present invention relates to the high frequency transistor field, relate in particular to the method that the dense boron in the base outside the emitter region injects in the bipolar hyperfrequency transistor of a kind of silicon.

Background technology

Along with the development of radio frequency (RF) and microwave (MW) technology, wired and wireless telecommunications operating frequency improves day by day, and corresponding structure and performance to semiconductor device has higher requirement.The high frequency active device the earliest be bipolar transistor (BJT), developed into GaAs field-effect transistor (GaAsFET) and High Electron Mobility Transistor structures such as (HEMT) now, each structure respectively has superiority, and can be applied in different frequency ranges and field.

The scale of the integrated circuit that present usefulness bipolar transistor and CMOS form is increasing, become the basis and the motive force of information industry, all be indispensable almost in every field, but in RF and MW application, the unit simulation circuit of single transistor and its composition still has its importance, particularly still relies on the discrete device characteristic in circuit such as the low hot-tempered sound of high frequency, linearity and power amplification.Bipolar transistor because have manufacturing process maturation, high relatively operating frequency, higher power gain, low noise and make up easily advantage such as matching network in civilian wired and wireless telecommunications operating frequency field (it has been generally acknowledged that below 3GHz) still tool have great advantage, have utilization widely.

Improving one of bipolar transistor high frequency performance main method according to transistor working principle is to reduce base resistance.Common bipolar high frequency transistor is to adopt the pectination strip structure, and the bipolar transistor of higher frequency adopts polycrystalline emitter junction structure mostly, and Fig. 1 is typical NPN high frequency bipolar transistor profile; In order to reduce the base resistance dense boron injection of the base outside the emitter region (outer base area) employing usually, method commonly used at present is after the base injects, by selecting method for implanting to inject dense boron, such method is except the independent photoetching of needs, in order to prevent to cause dense base and emitter junction short circuit owing to the register partial difference of photoetching and etching, need leave bigger spacing, therefore increased the area of light base, the resistivity of common light base is at 1-2K ohm, and the resistivity of dense base wants little one more than the order of magnitude, therefore method base resistance commonly used is bigger, also is the one of the main reasons that high frequency characteristics is difficult to improve.

Summary of the invention

The technical issues that need to address of the present invention have provided a kind of high frequency transistor design and manufacture method that adopts the autoregistration dense boron base, are intended to solve above-mentioned defective.

In order to solve the problems of the technologies described above, the present invention realizes by following steps:

After the polycrystal emitting area etching, utilize the photoresist on the polycrystal layer to inject dense boron as mask;

Be that other zone all is a concentrated boron area the light base under the emitter region of photoresist protection in active area, the area of polycrystal layer is identical with the area of light base;

The width of described polycrystal layer is between 0.6 micron and 2.5 microns; The width of polycrystal layer is according to the needs of design and the alignment precision decision of photoetching.

Compared with prior art, the invention has the beneficial effects as follows: owing to reduce base resistance is to determine that by the bar of control polycrystal emitting area is wide the self aligned method of dense base has reduced once dense base photoetching process and corresponding steps, has simplified technology and has made processing cost reduce about 1/7; Because can accurately to control light base bar wide according to the width of design polycrystal layer,, avoided the registration error of superposition, reduced base resistance, improved the high frequency characteristics of product: as improved characteristic frequency fT and power gain, reduced device hot-tempered.

Description of drawings

Fig. 1 is typical NPN high frequency bipolar transistor profile;

Fig. 2 adopts NPN high frequency bipolar transistor profile of the present invention;

Fig. 3 is the profile in photoetching and etching place, the light boron implantation step in base;

Fig. 4 is the profile in photoetching and the etching emitter region step among the present invention;

Fig. 5 is the profile in polycrystalline deposition, the polycrystalline implantation step;

Fig. 6 is the profile in photoetching and etching polycrystalline among the present invention, the dense boron implantation step;

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail:

In order to solve the problems of the technologies described above, the present invention realizes by following steps:

After the polycrystal emitting area etching, utilize the photoresist on the polycrystal layer to inject dense boron as mask;

Be that other zone all is a concentrated boron area the light base under the emitter region of photoresist protection in active area, the area of polycrystal layer is identical with the area of light base;

The width of described polycrystal layer is between 0.6 micron and 2.5 microns.

By Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 as seen: be the present invention in order to make embodiment of NPN high frequency transistor:

Silicon epitaxial wafer;

Growthing silica and silicon nitride;

Photoetching and etching place (active area);

Field oxide growth (10000-16000A);

The base injects;

Photoetching and etching emitter region;

Polycrystalline growth and polycrystalline inject As ⁺

Photoetching and etching polycrystalline;

Dense base injects;

Infrared short annealing;

Photoetching and etching contact hole

Metallization

Photoetching and etching sheet metal;

Surface passivation layer,

Photoetching and etching passivation layer.

Claims (2)

1. manufacture method that adopts the high frequency transistor of autoregistration dense boron base, realize by following steps:

After the polycrystal emitting area etching, utilize the photoresist on the polycrystal layer to inject dense boron as mask;

Be that other zone all is a concentrated boron area the light base under the emitter region of photoresist protection in active area, the area of polycrystal layer is identical with the area of light base;

2. the manufacture method of the high frequency transistor of employing autoregistration dense boron base according to claim 1, wherein: the width of described polycrystal layer is between 0.6 micron and 2.5 microns.

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