JPH0485965A - Manufacture of schottky barrier semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a Sirotchi barrier semiconductor device having a field plate made of Ti oxide.

[Conventional technology]

Shikosotoki barrier semiconductor devices are characterized by their high speed.

Although it has the advantage of low loss, it is inferior in high voltage resistance compared to pn junction elements, so improvements are required. In order to increase the breakdown voltage of Schittski barrier semiconductor devices, a device with a field plate structure was disclosed in Japanese Patent Application Laid-Open No. 63-94673.
No. 63-94674. In the field plate structure shown in FIG.
A field plate layer 3 is formed to surround the Schottky barrier metal electrode 2 in contact with the Schottky barrier metal electrode 12 .

This field plate layer 3 is intended to alleviate the electric field concentration near the surface of the underlying n-layer layer 2, particularly at the electrode end 31, and to increase the withstand voltage.

The field plate layer 3 is covered with a protective film 4, and an electrode 5 is in contact with the lower surface of the substrate. The above-mentioned Japanese Patent Application Publication No. 63-94673 and Japanese Patent Application Publication No. 63-9467
In Publication No. 4, a field plate is a high-resistance layer obtained by forming a thin film layer containing Ti as a main component on a semiconductor substrate and then performing heat treatment in an oxidizing atmosphere. When a reverse voltage is applied, a saturated current as a Schottky barrier diode flows in this field plate portion, but if the sheet resistance R3 of the field plate portion is an appropriate value commensurate with I, the current gradually decreases as it moves away from the electrode end 3I. The potential decreases, a stable potential distribution is formed along the length of the field plate, and electric field concentration is alleviated.

Therefore, if it is possible to obtain a field plate layer with the desired sheet resistance (100-1000 MΩ),
It becomes possible to obtain a Noyonotokiba 117 semiconductor device having a high breakdown voltage structure.

[Problem to be solved by the invention]

The n-type diode shown in FIG. 2 is manufactured by the steps shown in FIG. 3. The semiconductor body 1 shown in FIG. 3 (al) is made of GaAs, and has an n- layer 12 epitaxially grown on an n'' substrate 11. On the bottom surface of this n'' substrate 11, as shown in FIG. Au as shown
An ohmic contact electrode 5 made of a -Ge alloy is formed by vacuum evaporation. Next, as shown in FIG. 3 1cl,
An M layer having a thickness of about 1 mm is formed on the n-layer 12 by a vacuum deposition method and patterned by photoetching to obtain a barrier metal electrode 2. Further, in FIG. 3D, a Ti1ll film is formed on the entire surface of the element body 1 by the vacuum one-deposition method, and then patterned as a field plate layer. The thickness of the field plate layer is 100 to 300 people.

Subsequently, heat treatment is performed in an oxidizing atmosphere to oxidize the Ti thin film to obtain a highly resistive field plate layer 3. Thereafter, as shown in FIG. 3[al], the field plate layer 3 is covered with an insulator 11114 to obtain a Schottky barrier diode. Safe! As the l film 4, a 340 g film (silicon oxide film) or silicon nitride film formed by CVD method is used.

In the 31st ffl (C+ step) in this manufacturing method, an M layer is vacuum-deposited on the n-layer 12 to obtain barrier gold Ix1i42, but if an oxide film exists on the surface of the n-layer 12, , the forward drop voltage vF of the Schottky barrier diode increases.This increase in V increases the loss of the Schottky barrier diode as a rectifying element. In addition, in the above method, after forming the barrier gold at electrode 2 of the M layer, T i 'fil H is oxidized by heat treatment, so the surface of the M layer is also oxidized at the same time, resulting in a decrease in forward current density. occurs.

Therefore, although a Schottky barrier semiconductor device in which a highly resistive field plate layer is grown can have a high breakdown voltage, it also causes the above-mentioned problems, so it is desired to improve its forward characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a high-voltage Schottky barrier semiconductor device that has a high-resistance field plate for alleviating electric field concentration near the surface and has good forward characteristics. .

[Means to solve the problem]

In order to achieve the above object, the method for manufacturing a Schottky barrier semiconductor device of the present invention involves depositing a titanium film on the entire surface of a semiconductor layer, oxidizing the titanium film by heat treatment, and then etching the titanium oxide film. A field plate layer is formed by patterning, and then a Schottky barrier metal bridge is brought into contact with the exposed surface of the semiconductor layer surrounded by the field plate layer. Alternatively, after depositing a conductive layer in ohmic contact on the semiconductor substrate surface of a semiconductor body made by laminating a semiconductor layer of a low impurity concentration of the same conductivity type on a semiconductor substrate of a high impurity concentration of one conductivity type, A titanium film is deposited on the entire surface of the semiconductor layer, heated in an oxidizing atmosphere to oxidize the titanium, and then etched to pattern the titanium oxide film to form a field plate layer. A Schottky barrier metal electrode is brought into contact with the exposed surface of the semiconductor layer.

When a Ti film is applied to the entire surface of the semiconductor layer and then subjected to heat treatment, oxygen in the oxide film that previously existed on the surface of the semiconductor layer is incorporated into the Ti film. After that, the Ti oxide on the contact surface of the barrier metal electrode is etched for patterning.
When M is removed, the unoxidized surface of the semiconductor layer is exposed. When the barrier metal bridge is brought into contact with this surface, no increase in the forward voltage drop across the Schottky barrier occurs, and the heat treatment for forming Ti oxide is performed before depositing the barrier metal electrode. Second, there is no risk of oxidation of the electrode layer surface.On the other hand, since the electrode is deposited on the high impurity semiconductor substrate before the heat treatment for Ti1l oxidation, there is little oxidation of the substrate surface and it is good. A good ohmic contact can be obtained.

〔Example〕

FIG. 1 shows the manufacturing process of a Schottky barrier diode according to an embodiment of the present invention, and parts common to those in FIGS. 2 and 3 are given the same reference numerals.

FIG. 1 (al indicates a semiconductor element 1 made of GaAs,
This semiconductor body 1 consists of an n' substrate 11 and an n- layer 12 epitaxially grown thereon. As shown in FIG. sexual contact electrode 5
Next, as shown in FIG.
After forming the 1L film 6 on the entire surface by the vacuum one-layer method, the first
In Figure (d), a heat treatment is performed at a temperature of 400° C. for 10 minutes to oxidize Ti11m116 to form an oxidized Ti film 7. At this time, the oxygen in the oxide film on the surface of the n-layer is Ti oxide
Next, as shown in FIG. 1fa+, the Ti oxide film 7 is patterned by etching to form a field plate 113. By this step, the oxide film on the surface of the n- layer 12 other than the portion where the field plate layer is formed is removed. Furthermore, in FIG. 1ffl, M with a thickness of about 1-
After forming the layer by vacuum evaporation method, it is patterned,
Barrier metal bridge 2 is obtained. After this, as shown in FIG. 1 (phantom), the field plate layer 3 is covered with an insulating protective film 4 to obtain a Schottky barrier diode.
As the film 1114, an SiO□ film (silicon oxide film) or a silicon nitride film formed by CVD is used.

The Schottky barrier diode obtained by the above manufacturing method exhibited a withstand voltage (breakdown voltage) of 250 V. Also,
Forward voltage drop V, for a current density of 250 A/-,
0.8■ for 200 V withstand voltage (7) SiPINi
It showed a lower value than the iode.

Although the embodiments described above are for manufacturing Schottky barrier diodes, it is clear that the invention can be similarly implemented in manufacturing other semiconductor devices using Schottky barriers.

〔Effect of the invention〕

According to the present invention, by oxidizing the Ti film before depositing the barrier metal and patterning it to form a high-resistance field plate, an oxide film-free surface can be obtained on the barrier metal deposition surface, and Schottky An increase in forward voltage drop across the barrier was prevented.

In addition, since the heat treatment is performed before forming the barrier metal electrode, oxidation of the electrode l does not occur, preventing a decrease in forward current density, and improving the forward uniformity characteristics of the high voltage Schottky barrier semiconductor device. .

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the manufacturing process of a Schottky barrier diode according to an embodiment of the present invention in the order of fat to It is a sectional view showing a process in order of rat - Tsukuda. 1: GaAs element body, ll: n'' substrate, 12: n- layer, 2
: Barrier metal bridge, 3: Field plate layer, 5: A
u-Ge1i electrode, 6: Ti film, 7: Ti oxide film.

Claims (1)

[Claims] 1) A titanium film is deposited on the entire surface of the semiconductor layer, the titanium film is oxidized by heat treatment, the titanium oxide film is patterned by etching to form a field plate layer, and then a field plate layer is formed. A method for manufacturing a Schottky barrier semiconductor device, comprising bringing a Schottky barrier metal electrode into contact with an exposed surface of the semiconductor layer surrounded by a field layer. 2) After depositing an electrode layer in ohmic contact on the semiconductor substrate surface of a semiconductor body formed by laminating a semiconductor layer of a low impurity concentration of the same conductivity type on a semiconductor substrate of a high impurity concentration of one conductivity type, A titanium film is deposited on the entire surface of the semiconductor layer, heated in an oxidizing atmosphere to oxidize the titanium, and then etched to pattern the titanium oxide film to form a field plate layer. A method for manufacturing a Schottky barrier semiconductor device, characterized in that a Schottky barrier metal electrode is brought into contact with the exposed surface of the semiconductor layer. 3) The method for manufacturing a Schottky barrier semiconductor device according to claim 1 or 2, wherein the semiconductor is gallium arsenide. 4) The method for manufacturing a Schottky barrier semiconductor device according to claim 1 or 2, wherein the Schottky barrier metal is aluminum.