CN203406288U - Bipolar transistor with improved BVcbo (collector-base breakdown voltage) - Google Patents

Abstract

The utility model discloses a bipolar transistor with an improved BVcbo. A groove field oxidation isolation technology and a junction termination technology are combined. Meanwhile, a groove field oxidation process is divided into two steps. The injection of junction termination boron ions is performed between the two field oxidation steps. A proper junction depth of Junction termination boron can be obtained. The technological process is further simplified. A junction termination ion injection window is not required to be aligned with the edge of a groove. Therefore, a relatively fixed doped boron concentration can be obtained on a part where a junction termination and the groove intersect with each other. A stable BVcbo can be also acquired. An NPN silicon bipolar type microwave power transistor device made by using the technological method can have the BVcbo improved by more than 20 volts and further provide high output power. Collector junction parasitic capacitance can be alleviated. The high-frequency performance of the device can be further guaranteed.

Description

A kind of bipolar transistor that improves BVcbo

Technical field

The utility model has related to a kind of transistor, has especially related to a kind of bipolar transistor that improves BVcbo, belongs to electronic technology field.

Background technology

High frequency power transistor device is widely used in communication system and radar system, and the application designing requirement of microwave power transistor device can provide high power output and high gain, and operating frequency range is from hundreds of MHz to several GHz.For reaching such high-output power, high-gain and high frequency requirement, except the selection of the layout of chip device, technological parameter and encapsulation are optimized, sometimes even more important to the improvement of transistor chip manufacturing process.Reason is as follows:

1, in order to obtain high power output, should select high as far as possible collector region doping content, to suppress the saturated phenomenon of collector region output current, simultaneously denseer collector region doping can be selected thinner epitaxy layer thickness, the dead resistance of collector region is less like this, thereby can obtain good transistor high frequency performance.But the problem that the doping of denseer collector region brings is lower BVcbo.

2, in order to obtain high frequency performance, the base junction depth more shallow (0.2 to 0.5 micron) of common planar transistor, more shallow base junction depth makes the metallurgical junction radius of curvature of collector region-base less, so that while adding reverse bias voltage in collector region-base, because electric field tends to concentrate on less radius of curvature place, cause less BVcbo.In order to overcome the shortcoming that shallow junction BVcbo is less, a kind of technology of tying terminal that is called is used, at edge, shallow junction base, add a step degree of depth darker with Impurity Diffusion base same polarity, the metallurgical junction radius of curvature that obtains larger collector region-base is to improve BVcbo.But the problem that knot terminal technology is brought is the horizontal proliferation due to impurity, transistorized area is increased, cause the parasitic capacitance of collector region-base to increase, reduced transistorized frequency performance.

3, groove field oxidation isolation technology technology, because its transistor area is little, greatly reduced collector junction parasitic capacitance, improved transistorized high frequency performance, is widely used in ambipolar high-frequency small power transistor.For microwave power transistor device, due to its power output of having relatively high expectations, utilize separately groove field oxidation isolation technology technology and be not suitable for, this be because: the doped chemical boron ion of transistor base tends to be absorbed (fractional condensation) in field oxide in thermal process, make to reduce in the boron concentration at silicon-silicon oxide interface place, be subject to the impact of silicon-silicon oxide interface electric charge, BVcbo also can reduce.

Utility model content

Technical problem to be solved in the utility model is to provide a kind of bipolar transistor that improves BVcbo, has not only improved puncture voltage, and high power output can be provided, and has reduced collector junction parasitic capacitance, has guaranteed the high frequency performance of device.

In order to solve the problems of the technologies described above, the technical scheme that the utility model adopts is:

A kind of bipolar transistor that improves BVcbo, the N-type silicon substrate that comprises high-concentration dopant, the top of described N-type silicon substrate is provided with N-type epitaxial silicon, the both sides of described N-type epitaxial silicon are formed with smooth oxide layer by groove, oxidation and smooth micronizing technology, the upper surface of the N-type epitaxial silicon between described two smooth oxide layers is provided with intrinsic base region, the both sides of described intrinsic base region are provided with extrinsic base region, between described two extrinsic base regions, are also provided with emitter region; Between described two smooth oxide layers, by thermal process impurity activation, form the second metallurgical junction.

Aforesaid a kind of bipolar transistor that improves BVcbo, it is characterized in that: above described N-type epitaxial silicon, be also deposited with dielectric material, on the dielectric material at described extrinsic base region and place, emitter region, by photoetching and etching, form the contact hole of base stage and emitter, in described contact hole, be provided with metal rat tail.

The beneficial effects of the utility model are: by groove field oxidation isolation technology technology and knot end process technology are combined, and the field oxidizing process of groove is divided into two steps, knot terminal boron Implantation is arranged between two step field oxidations and carries out, not only can obtain reasonably tying the junction depth of terminal boron, and simplified technological process, and due to knot terminal Implantation window with slot wedge without aiming at, the doped with boron concentration that therefore can obtain comparatively fixing at the intersection of tying terminal and groove, so that can obtain stable BVcbo, make NPN silicon ebipolar microwave power transistor device not only improve BVcbo more than 20 volts, high power output can be provided, and reduced collector junction parasitic capacitance, guaranteed the high frequency performance of device.

Accompanying drawing explanation

Fig. 1 is a kind of structural representation that has improved the bipolar transistor of BVcbo of the utility model.

Fig. 2 is the transistor arrangement schematic diagram corresponding with step (1) in the manufacture method of a kind of bipolar transistor that has improved BVcbo of the utility model;

Fig. 3 is the transistor arrangement schematic diagram corresponding with step (2) in the manufacture method of a kind of bipolar transistor that has improved BVcbo of the utility model;

Fig. 4 is the transistor arrangement schematic diagram corresponding with step (3) in the manufacture method of a kind of bipolar transistor that has improved BVcbo of the utility model;

Fig. 5 is the transistor arrangement schematic diagram corresponding with step (4) in the manufacture method of a kind of bipolar transistor that has improved BVcbo of the utility model;

Fig. 6 is the transistor arrangement schematic diagram corresponding with step (5) in the manufacture method of a kind of bipolar transistor that has improved BVcbo of the utility model;

In figure: 50, N-type silicon substrate, 51, part field oxide, 52, epitaxial silicon, 53, silicon dioxide, 54, silicon nitride, 55, groove, 56, photoresist, 57, inject window, 58, field oxide, 60, the first metallurgical junction, 62, smooth field oxide, the 64, second metallurgical junction, 66, intrinsic base region, 68, extrinsic base region, 70, emitter region, 72, medium, 76, metal rat tail.

Embodiment

Below in conjunction with Figure of description, the utility model is further described.

As shown in Figure 1, a kind of bipolar transistor that improves BVcbo, because the back side of wafer is the collector electrode C that is used to form NPN transistor, so in order to reduce the series resistance of collector electrode, we select the N-type silicon substrate 50 of high-concentration dopant as transistorized extrinsic collector region, the top of described N-type silicon substrate 50 is provided with N-type epitaxial silicon 52 as transistorized intrinsic collector region, groove is passed through in the both sides of described N-type epitaxial silicon 52, oxidation and smooth micronizing technology are formed with smooth oxide layer 62, the upper surface of the N-type epitaxial silicon 52 between described two smooth oxide layers 62 is provided with intrinsic base region 66, the both sides of described intrinsic base region 66 are provided with extrinsic base region 68, between described two extrinsic base regions 68, be also provided with emitter region 70, between described two smooth oxide layers 62, by thermal process impurity activation, form the second metallurgical junction 64, above N-type epitaxial silicon 52, be also deposited with dielectric material 72, on the dielectric material 72 at 70 places, 68He emitter region, described extrinsic base region, by photoetching and etching, form the contact hole of base stage and emitter, in described contact hole, be provided with metal rat tail 76.

Produce above-mentioned a kind of technology method that has improved the bipolar transistor of BVcbo, specifically comprise the steps:

(1) select a kind of N-type silicon substrate 50 of high-concentration dopant as the extrinsic collector region of NPN transistor, N-type silicon substrate 50 back sides, after transistor fabrication flow process completes, are carried out attenuate, are steamed gold, are used to form transistorized collector electrode C; Wherein, the crystal orientation of N-type silicon substrate 50 can be<111>, can be also<100>, but conventionally select<111>crystal orientation, the impurity element of mixing can be arsenic (As), also can be phosphorus (P) or antimony (Sb), but conventionally select arsenic, the resistivity of N-type silicon substrate 50 is elected as and is not more than 0.003Wcm; At the top of N-type silicon substrate 50, be that the epitaxial silicon 52 of N-type low concentration doping is as the intrinsic collector region of NPN transistor, as shown in Figure 2, the doped chemical of epitaxial silicon 52 can be arsenic (As), also can be phosphorus (P) or antimony (Sb), but arsenic normally, the resistivity of epitaxial silicon 52 is 0.1Wcm to 3.5Wcm, and thickness is 2 to 20 microns.

(2) by thermal oxidation technology at the thin silicon dioxide 53 of epitaxial silicon 52 surface production one decks, by LPCVD technique deposition thickness, be and then the silicon nitride 54 of 1500 dusts again, by photoetching technique, provide groove figure; With dry etching technology successively local etching, fall silicon nitride 54, silicon dioxide 53 and epitaxial silicon 52 to form groove 55, as shown in Figure 3.

(3) by high temperature thermal oxidation metallization processes, carry out the first step field oxidation forming section field oxide 51 of groove 55; Then the active area of 56 protective transistors with photoresist above silicon nitride 54, and at the two ends of silicon nitride 54, expose the injection window 57 of knot terminal boron ion, as shown in Figure 4.By injecting window 57, carry out the injection of boron ion, implantation dosage is every square centimeter, 5.0E12-5.0E14 ion, because the thickness of the first step field oxidation forming section field oxide 51 of groove can stop that boron Implantation is in place, so knot terminal Implantation window 57 with groove 55 edges without aiming at, the doped with boron concentration that therefore can obtain comparatively fixing at the intersection of tying terminal and groove 55.

(4) knot terminal boron ion, from injection window 57 has injected, is removed photoresist 56; The second step field oxidation of carrying out groove 55 forms field oxide 58, in the heat of oxidation process of the second step field of groove 55, the knot terminal B ion injecting is advanced to the degree of depth of 1.0 microns to 5.0 microns, forms the first metallurgical junction 60 of P-type knot terminating layer and N-type epitaxial loayer, as shown in Figure 5.

(5) after groove 55 field oxides form, with hot phosphoric acid corrosion, get rid of the silicon nitride 54 of protective transistor active area; For be conducive to below respectively walk photoetching process, with returning, carve flatening process technology groove 55 field oxides that exceed active area silicon plane etched away, form smooth field oxide 62, as shown in Figure 6.

(6) extrinsic base region 68, the dense arsenic ion injection technology that adopt traditional shallow junction base technique to form intrinsic base region 66, dense boron ion implantation technology formation ohmic contact form emitter region 70; After thermal process impurity activation technique, just form the second metallurgical junction 64 that LiaoP-Xing district and N-type intrinsic collector region form; After deposit one deck dielectric material 72, photoetching and etching to be to form the contact hole of base stage (B) and emitter (E), then carry out silicide process processing with the contact resistance of reduction electrode, and metal line technique forms the metal rat tail 76 of each electrode; Finally, use passivation layer technique protective transistor surface not to be subject to the impact of environment, the product of final molding as shown in Figure 1.

Wherein, the best results when degree of depth of the groove 55 described in step (2) is selected the numerical value between 0.3 micron to 2.5 microns after repeatedly testing, and the temperature of in step (3), groove 55 being carried out to thermal oxidation is generally 1050 ℃-1200 ℃, the thickness of the part field oxide 51 forming is 0.5 micron to 3.0 microns, after secondary oxidation, the gross thickness of the field oxide 58 in step (4) is 1.0 microns to 3.5 microns.

In sum, a kind of bipolar transistor that improves BVcbo that the utility model provides, has not only improved puncture voltage, high power output can be provided, and reduce collector junction parasitic capacitance, has guaranteed the high frequency performance of device.

More than show and described basic principle of the present utility model, principal character and advantage.The technical staff of the industry should understand; the utility model is not restricted to the described embodiments; that in above-described embodiment and specification, describes just illustrates principle of the present utility model; do not departing under the prerequisite of the utility model spirit and scope; the utility model also has various changes and modifications, and these changes and improvements all fall within the scope of claimed the utility model.The claimed scope of the utility model is by appending claims and equivalent circle thereof.

Claims (2)

1. a bipolar transistor that improves BVcbo, it is characterized in that: the N-type silicon substrate (50) that comprises high-concentration dopant, the top of described N-type silicon substrate (50) is provided with N-type epitaxial silicon (52), groove is passed through in the both sides of described N-type epitaxial silicon (52), oxidation and smooth micronizing technology are formed with smooth oxide layer (62), the upper surface of the N-type epitaxial silicon (52) between described two smooth oxide layers (62) is provided with intrinsic base region (66), the both sides of described intrinsic base region (66) are provided with extrinsic base region (68), between described two extrinsic base regions (68), be also provided with emitter region (70), between described two smooth oxide layers (62), by thermal process impurity activation, form the second metallurgical junction (64).

2. a kind of bipolar transistor that improves BVcbo according to claim 1, it is characterized in that: above described N-type epitaxial silicon (52), be also deposited with dielectric material (72), the upper contact hole that forms base stage and emitter by photoetching and etching of dielectric material (72) that described extrinsic base region (68) and emitter region (70) are located, is provided with metal rat tail (76) in described contact hole.

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