JP2576165B2 - Manufacturing method of bipolar transistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a bipolar transistor.

[Background Art] A bipolar transistor has an excellent feature that its current driving capability is larger than that of a field effect transistor. For this reason, in recent years, research and development of bipolar transistors using not only Si but also compound semiconductors such as GaAs have been actively conducted. In particular, in bipolar transistors using compound semiconductors, the emitter-base junction can be configured as a heterojunction by using molecular beam epitaxy (hereinafter referred to as MBE) technology.
There are advantages such as a high emitter injection efficiency.

2 (a) to 2 (c) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a conventional method of manufacturing a bipolar transistor.

In this conventional example, first, as shown in FIG.
An n-GaAs layer 2, a p-GaAs3 and an n-AlGaAs layer 4 are sequentially formed on a semi-insulating GaAs substrate 1 by the MBE method. ₂ After forming the film 6, using this as a mask, p
An AuZnNi layer 9 is formed on the GaAs layer 3 in a self-aligned manner. Here, on the emitter electrode 11a composed of an AuGeNi layer,
The iO ₂ film 6 and AuZnNi layer 9 remain.

Subsequently, a photoresist film 10a having a predetermined pattern to cover the emitter electrode 11a is formed, the width W _B of the base electrode is set to be a predetermined value.

Next, as shown in FIG. 2B, a photoresist film 10a is formed.
The AuZnNi layer 9 is etched using
9a and the p-GaAs layer 3 and n
-Remove the surface of the GaAs layer 2 and further form a photoresist film 10a.
Is used as a mask to form an ohmic metal on the surface of the n-GaAs layer 2.
An AuGeNi layer 11 is deposited from above.

Next, as shown in FIG. 2 (c), the photoresist film 10a is dissolved in an organic solvent and lift-off is performed to form a collector electrode 11b.

[Problems to be solved by the invention]

In the conventional method for manufacturing a bipolar transistor described above, first, after forming the emitter electrode 11a, the base electrode 9 is formed.
a is formed, and then the collector electrode 11b is formed. Therefore, in this method, it is necessary to perform the conductor layer deposition step three times.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a bipolar transistor having extremely excellent high-speed and high-frequency characteristics by forming an emitter electrode and a collector electrode in a self-aligned manner on a base electrode. An object of the present invention is to provide a method of manufacturing a bipolar transistor with improved manufacturing yield and mass productivity.

[Means for solving the problem]

The method of manufacturing a bipolar transistor according to the present invention comprises the steps of: forming a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a third semiconductor layer of the first conductivity type on a semi-insulating substrate; A step of sequentially depositing a body layer, a step of forming a first mask having a predetermined pattern on the insulator layer, and sequentially using the first mask to sequentially form the insulator layer and the third semiconductor layer. Forming an emitter layer (or a collector layer) made of the third semiconductor layer by removing the first conductive layer, and removing the first mask to form a first conductive layer on the entire surface including the surface of the insulator layer. Forming a second mask having a predetermined pattern on the first conductor layer to selectively expose the first conductor layer on the insulator layer; and forming the second mask on the insulator layer. Using a mask, the first conductor layer and the second semiconductor layer Forming a base electrode made of the first conductor layer and a base layer made of the second semiconductor layer in a self-aligned manner with respect to the emitter layer (or the collector layer) by etching and removing the base layer; After removing the insulator layer by etching,
Forming a second conductor layer on the first semiconductor layer and the emitter layer (or the collector layer) by using the above mask, thereby sequentially forming a collector electrode (or an emitter electrode) and an emitter electrode (or a collector electrode). Simultaneously and in a self-aligned manner with respect to the base electrode.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 (a) to 1 (f) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining one embodiment of the present invention.

First, as shown in FIG. 1A, an n-GaAs layer 2 as a first semiconductor layer, a p-GaAs layer 3 as a second semiconductor layer, and a third semiconductor layer are formed on the surface of a semi-insulating GaAs substrate 1. As n
After the AlGaAs layer 4 is sequentially formed by the MBE method, hydrogen ions (H ⁺ ) are implanted into other portions except for the portion where the bipolar transistor is formed to form the insulating region 5.

Next, as shown in FIG. 1 (b), the n-AlGaAs layer 4
After sequentially forming an SiO ₂ film 6 and a photoresist film 7 having a predetermined pattern, using the photoresist film 7 as a mask, the SiO ₂ film 6 is removed by a reactive ion beam etching method, and phosphoric acid and hydrogen peroxide are further added. The n-AlGaAs layer 4 is etched with a mixed solution of water and water to expose the surface of the p-GaAs layer 3.

Next, as shown in FIG.
Is removed, a photoresist film 8 is formed on the insulating region 5, and an ohmic connection with the n-GaAs layer 2 is formed from above.
An AuZnNi layer 9 is deposited.

Next, as shown in FIG. 1 (d), after washing with an organic solvent to remove the photoresist film 8, a photoresist film 10 having a predetermined pattern for forming a collector electrode is formed. Subsequently, after the surface of the photoresist film 10 is etched by reactive ion beam etching to expose the AuZnNi layer 9 on the SiO ₂ film 6, the AuZnNi layer 9 is removed.
It is removed by etching by ion milling method using Ar ⁺ , and p
Etching the GaAs layer 3 to expose the n-GaAs layer 2 in the region where the collector electrode is to be formed.

Next, as shown in FIG. 1 (e), after etching the SiO ₂ film 6 with buffered hydrofluoric acid, the n-GaAs
An AlGeNi layer 11 for ohmic connection with the layer 2 and the n-AlGaAs layer 4 serving as an emitter layer is deposited. At this time, an emitter electrode 11a and a collector electrode 11b are simultaneously formed on the surfaces of the n-GaAs layer 2 and the n-AlGaAs layer 4 in self-alignment with the base electrode 9a.

Finally, as shown in FIG.
By removing 10, the AuGeNi layer 11 is lifted off, so that a compound semiconductor bipolar transistor can be obtained.

In the above embodiment, the emitter-top type is described. However, the present invention is not limited to this, and the collector-top type can be similarly implemented, and the effect is the same.

Further, the semiconductor using GaAs and AlGaAs has been described, but the present invention is not limited to this, and other compound semiconductors such as InP and InGaAs may be used. Further, as the insulating film, the above-mentioned SiO ₂
Not limited to the film, a nitride film such as SiN _X may be used.

〔The invention's effect〕

As described above, the present invention shortens the manufacturing process by simultaneously forming the emitter electrode and the collector electrode, and arranges the emitter electrode and the collector electrode on the base electrode in a self-aligned manner, thereby achieving high-speed and high-frequency characteristics. There is an effect that an extremely excellent compound semiconductor bipolar transistor can be realized.

As a result, the number of manufacturing steps in the manufacture of a bipolar transistor having a cutoff frequency of 30 GHz or more can be reduced, and not only can the yield and element characteristics be improved, but also mass production can be achieved and the price can be reduced.

[Brief description of the drawings]

1 (a) to 1 (f) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention, and FIGS. 2 (a) to 2 (c) show a conventional method for manufacturing a bipolar transistor. FIG. 4 is a cross-sectional view of a semiconductor chip shown in the order of steps for explaining the method. 1 GaAs substrate, 2 n-GaAs layer, 3 p-GaAs
Layer, 4 ...... n-AlGaAs layer, 5 ...... insulating region, 6 ...... SiO ₂
Film, 7,8 ... Photoresist film, 9 ... AuZnNi layer, 9a ...
Base electrode, 10 ... Photoresist film, 11 ... AuGeNi layer,
11a: Emitter electrode, 11b: Collector electrode.

Claims (1)

(57) [Claims] A first conductive type first semiconductor layer, a second conductive type second semiconductor layer and a first conductive type third semiconductor layer on a semi-insulating substrate;
Sequentially depositing a semiconductor layer and an insulator layer, forming a first mask of a predetermined pattern on the insulator layer, and using the first mask to form the insulator layer and the third The third semiconductor layer is sequentially etched and removed to remove the third semiconductor layer.
Layer (or collector layer) consisting of semiconductor layers
Forming a first conductive layer on the entire surface including the surface of the insulator layer after removing the first mask; and forming a second mask having a predetermined pattern on the first conductive layer. And selectively exposing the first conductor layer on the insulator layer; and forming the first conductor layer using the second mask.
The base layer made of the first conductive layer and the base layer made of the second semiconductor layer are turned into the emitter layer (or the collector layer) by sequentially etching and removing the conductive layer and the second semiconductor layer. Self-aligning with the first semiconductor layer and the emitter layer (or collector layer) using the second mask after the insulator layer is removed by etching. Forming a collector electrode (or an emitter electrode) and an emitter electrode (or a collector electrode) simultaneously and in a self-aligned manner with respect to the base electrode by forming a conductor layer of a bipolar transistor. Production method.