JPS6370568A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a bipolar type semiconductor device operating at high speed by forming the size of an emitter layer at a large value so as to be kept within a range of a specific value in the vertical direction to the directions of the junctions of a base and an emitter by using a low-temperature epitaxial growth method on a thinly shaped base layer. CONSTITUTION:An N-type high concentration layer (atomic concentration of 1X10<20>/cm<3>) 2 is formed onto a P-type Si substrate 1. An N-type Si crystal layer 3 is shaped onto the substrate 1 by employing an epitaxial growth method. A P-type crystal layer having 200nm thickness and concentration of 1X10<19>cm<3> of impurity atoms is formed onto the layer 3 by using a low-temperature epitaxial growth method as a base layer 4. An N-type epitaxial crystal layer is shaped in impurity concentration of 1X10<20>/cm<3> and thickness of 0.3mum-1mum as an emitter layer 5. A wiring layer consisting of Al is formed to a predetermined pattern, and an emitter electrode 13, a base electrode 14 and a collector electrode 15 are shaped, thus forming a semiconductor device. Accordingly, the emitter layer having long-sized dimensions in the direction of a junction is formed onto a thin base region, thus preventing the lowering of injection efficiency, then acquiring the bipolar type semiconductor device operating at high speed.

Description

[Detailed Description of the Invention] [Summary] Manufacture of a bipolar semiconductor device that operates at high speed using an St crystal alone, without adopting a heterostructure such as a silicon carbide crystal formed on a silicon (St) crystal. The method comprises using a low-temperature epitaxial growth method on a base layer formed thinly to 200 nm or less so that the emitter layer has a dimension in the range of 0.5 μm to 1 μm in the direction perpendicular to the junction direction of the base and emitter. A bipolar semiconductor device that operates at high speed can be obtained by forming a large semiconductor device.

C. Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a high-speed bipolar semiconductor device formed using only Si crystal.

Bipolar semiconductor devices that constitute semiconductor devices such as ICs and LSIs are required to operate at increasingly higher speeds.

Generally, in a bipolar semiconductor device, the base transit time τB of the device is expressed using (1)2.

τB = WB" / ηD (1) Here, tVB is the base width, η is a coefficient determined by the profile of the impurity atom concentration in the base layer, and D is the base width. This is the diffusion length of injected carriers within a layer.

As can be seen from this equation (11), it is found that in order to operate the bipolar semiconductor device at high speed, it is better to make the base width WB smaller.

However, if this is done, there is a problem that the base resistance increases because it is inversely proportional to the base width WB.

Therefore, the concentration of impurity atoms in the base layer is increased (
There is a need to.

However, this reduces the emitter injection efficiency and
A problem arises in that the signal injected into the emitter cannot be amplified.

[Conventional technology]

Therefore, a conventional semiconductor device that solves this problem is formed by stacking a crystal layer such as silicon carbide (SiC), which has a larger energy band gap than a Si crystal, on a Si crystal in a heterostructure as an emitter layer. We are developing wide-gap transistors in which the barrier to electrons is greater than the barrier to electrons.

[Problem that the invention seeks to solve]

However, in a semiconductor device in which such a semiconductor crystal is formed into a heterostructure, there is a problem that the crystal cannot be stably formed with good reproducibility at the hetero interface.

Here, the electron injection efficiency γ in a bipolar semiconductor device approximately has a relationship as shown in equation (2).

γ-(1+ (Dp /Dn) (Wb/We) (Na/
Nd) ) --- (2) In this equation (2), o
p is the diffusion coefficient of P-type carriers, Dn is the diffusion coefficient of N-type carriers, persimmon is the base width, direction is the emitter width, Na is the acceptor concentration, and Nd is the donor concentration.

From this equation (2), we can increase the electron injection efficiency γ, that is, 1
In order to get closer to , it is better to reduce the second term of equation (2).

In order to lower the base resistance so that the bipolar transistor can operate at high speed, increasing the base concentration Na causes γ to decrease according to equation (2), but this decrease in γ can be achieved by increasing the emitter width direction. It can be prevented.

Based on the above-mentioned points, the present invention uses Si crystal alone without using an unreliable crystal structure such as a heterojunction, reduces the base layer thickness, and forms a large emitter width -e. To obtain a bipolar semiconductor device that operates at high speed.

[Means for solving problems]

The method for manufacturing a semiconductor device of the present invention includes forming a high concentration impurity layer of a conductivity type opposite to that of the substrate on a silicon substrate, forming a low concentration layer of conductivity type opposite to that of the substrate, and forming the low concentration layer on the low concentration layer. Concentration layer and reverse y! , a step of forming an impurity layer of a conductivity type to a thickness of 200 nanometers (nm) or less to form a base layer; forming a silicon crystal layer of a conductivity type opposite to the base layer on the base layer with a thickness of 0.5 μm to 1 μm; After forming an insulating film on the substrate, a step of anisotropically etching the silicon crystal layer to form an emitter layer in a predetermined pattern; A window is opened on the high concentration region formed on the substrate, and a metal film is formed on the window to form an electrode.

[Effect]

The method for manufacturing a semiconductor device of the present invention uses a Si crystal alone without forming a heterostructure, forms a base concentration to a thickness of 200 nm or less, and forms an emitter layer thereon using a low-temperature epitaxial growth method. 0.5 μ in the vertical direction to the base-emitter junction
By forming the transistor as large as m to 1 μm, the formed transistor can be operated at high speed, and the value of T, which is the injection efficiency of the emitter, can be kept high.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

First, as shown in FIG. 1, N-type atoms such as arsenic are ion-implanted or diffused onto a P-type St substrate 1 whose surface has a (100) plane, resulting in a high concentration of N-type N (atoms). Concentration I
IO”/am”) 2.

Next, N is grown on the substrate 1 using an epitaxial growth method.
A type Si crystal layer 3 is formed.

Furthermore, a P-type crystal layer having a thickness of 200 nm and an impurity atom concentration of IXIO+9/crn3 is formed thereon as a base layer 4 using a low-temperature epitaxial growth method.

Then, disilane (
5izllb) Using a low-temperature epitaxial growth method using gas as a growth gas, an N-type epitaxial crystal layer is used as the emitter layer 5, and the impurity concentration is 1 × 1Q20/
(Form Jl+' to a thickness of 0.3 μm-1 μm.

Furthermore, as shown in FIG. 2, a silicon nitride film (not shown) with a predetermined pattern is used as a mask and a thermal oxidation method is used to deposit a predetermined pattern of SiO□ for element isolation on the substrate.
A film 6 and a 5iOz film 7 for base and collector separation are formed.

Furthermore, as shown in FIG. 3, a 5i02 film was deposited on the substrate by CVD.
After forming using the D method, a predetermined pattern of the 5in2 film 8 is formed using a photolithography method.

Next, using this SiO□ film 8 as a mask, the N-type 5iji5, which will become the emitter layer, is anisotropically etched using caustic potassium (KOH) etching solution. It is removed using an etching solution consisting of a mixture of hydrogen acid and ammonium fluoride.

In this way, as shown in FIG.
An emitter layer 9 having a predetermined pattern of μm-1 μm is formed.

Next, as shown in FIG. 4, the substrate was introduced into a reaction chamber (not shown), the pressure inside the reaction chamber was set to 5 Kg/cm'', and oxygen (0□) gas was introduced into the reaction chamber. Then, 10 SiO□ films are formed on the substrate using a high-pressure oxide film forming method in which the temperature in the reaction chamber is set to 800° C. or lower.

Next, as shown in FIG. 5, after forming a photoresist film (not shown) on the substrate, this photoresist film is opened in a predetermined pattern, and using this photoresist film as a mask, the film 10 is etched by dry etching. A window is opened above the collector high concentration formation region and N type impurity atoms are ion-implanted to form the collector high concentration layer 11.

Furthermore, as shown in FIG. 6, a 5iOz film 10 is formed on the base region.
After opening in a predetermined pattern, P-type impurity atoms are ion-implanted to form a highly concentrated base region 12, and the 5i02 film 10 on the emitter formation layer 9 is further opened.

Furthermore, as shown in FIG. 7, 11
After forming the wiring layer A/, the wiring layer A/ is formed into a predetermined pattern using photolithography and dry etching to form an emitter electrode 13, a base electrode 14, and a collector electrode 15 to complete the semiconductor device. Form.

In this way, an emitter layer with long dimensions in the junction direction is formed on a thin base region, and a high-speed bipolar semiconductor can be produced without reducing injection efficiency and without using a heterostructure. A device is obtained.

In the above embodiment, a P-type substrate is used and an N"
On top of that, an N-type Si layer, a thin P-type layer to serve as a base, and a thick N-type layer to serve as an emitter were formed.
Similar results can be obtained by forming 24 layers on an St-type substrate and then forming a P-type Si layer, a thin N-type layer as a base, and a thick P-type layer as an emitter thereon.

〔Effect of the invention〕

As described above, according to the method of the present invention, there is an effect that a bipolar type semiconductor device that does not reduce injection efficiency and operates at high speed can be obtained.

[Brief explanation of the drawing]

FIG. 1 to FIG. 7 are cross-sectional views for explaining the method of manufacturing a semiconductor device according to the present invention in the order of steps. In the figure, (2) is a P-type Si substrate, 2 is a high concentration N-type layer, 3 is an N-type Si layer, 4 is a base layer, 5.9 is an emitter layer, 6, 7, 8°1
0 is 5in2 film, 11 is collector high concentration layer, 12 is base height) 1 degree layer, 13 is emitter electrode, 14 is base electrode, 18th Komei Natsume Ryo? wI example is old δ702 membrane type 8゜engineering section 1m2
Figure 5: Emi/Z in the heat Figure No. 6: 1 case of flashing → Emi γ-ri - Jinkoshikuto ΦFutake 1 SoshakuNio to figure 7

Claims (2)

[Claims] (1) After forming a high concentration impurity layer (2) of a conductivity type opposite to that of the substrate (1) on a silicon (Si) substrate (1), a low concentration layer (2) of a conductivity type opposite to that of the substrate (1) is formed thereon. 3), and an impurity layer of the opposite conductivity type to the low concentration layer (3) is formed on the low concentration layer (3) to a thickness of 200 nanometers (nm) or less to form a base layer (4). Step: After forming a silicon crystal layer (5) of a conductivity type opposite to the base layer (4) on the base layer (4) to a thickness of 0.3 μm to 1 μm, the silicon crystal layer (5) is formed on the base layer (4). A step of forming an emitter layer (9) in a predetermined pattern by anisotropic etching, after forming an insulating film (10) on the substrate, on the emitter layer (9) and on the base high concentration region (7). A method of manufacturing a semiconductor device is further characterized in that a window is opened above the collector high concentration region (11) and a metal film is formed on the window in a predetermined pattern to serve as an electrode. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the emitter layer (9) is formed by a low-temperature epitaxial growth method.