JPS60160120A - Formation of electrode for semiconductor element - Google Patents

Abstract

PURPOSE:To prevent deterioration of a semiconductor element and to obtain a highly reliable electrode by a method wherein the window having a stepping is provided on an insulating film, and a prescribed metal and Au are laminated on the window and the stepping. CONSTITUTION:A window 8 is provided on the SiO2 film 2 located on an Si substrate 1, the resist mask 10 of window 9 larger than the window 9 is provided, and a stepping 7 is formed by performing an etching. Then, Ti 3, Pt 4 and Au 5 are vapor-deposited successively, and the layers 3-5 are removed together with the resist 10. According to this constitution, the disconnection of the Ti 3 and the Pt 4 can be prevented, the infiltration of Au generating when an annealing is performed can be prevented and the deterioration of Si element can also be prevented by having the small stepping 6 of the insulating film 2. Besides, a multilayer metal layer is composed of at least two kinds of Au selected from Ti, Pt, Pd and W.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a method for forming an electrode for a semiconductor device.

[Prior art]

Semiconductor devices have heretofore been used for a wide range of purposes, many of which are used under harsh conditions and where maintenance is difficult. These devices are required to have excellent characteristics and high reliability. One of the causes of reduced reliability is the deterioration that progresses due to the reaction between the electrode and the semiconductor.

Conventionally, a small amount of doping impurity (Zn, 8i.

Ohmic electrodes with a structure in which Au containing Ge, etc.) are brought into direct contact with the semiconductor have been widely used, but this structure has the problem that the electrode metal and semiconductor react at low temperatures, which sometimes significantly degrades the device. there were. To solve this problem, TI, Pi.

High melting point gold such as pd, w, Mt-sandwiched Ti/(P
t, Pd.

W)/Au multilayer metal electrodes have attracted attention. Ti/P
The TLM U electrode has a three-layer structure using Ti as an alloy layer, Au as a bonding pad, and Pt, a high melting point metal, as a barrier metal for Au sandwiched between these two layers. This is one of the most representative books on structural electrodes, and has attracted a lot of attention.

FIG. 1 is a sectional view of a main part of a conventional Ti/Pt/Au multi-striped structure electrode element.

An insulating film 2 is provided on a semiconductor substrate 1, and a contact window is provided. And 11 layers 3. A Pt layer 4 and an Au layer 5 are laminated to form a multilayer electrode.

In the cono structure, three layers of Ti/Pt/Au gold jIIg#
In order to cover the top of the insulating film 2 and prevent contamination from the outside, an electrode gold Jl is formed on the insulating film step 6. However, if the metal coverage in the insulating film step 6 is poor, the Au layer 5 may become 11 during heat treatment. Layer 3. The Au atoms penetrate to the semiconductor surface along the interface between the Ptjd 4 and the insulating film 2, and the Au atoms react with the semiconductor, causing the alloy layer to advance to a deep position, causing deterioration.

Here, 11 layers 3. It is also possible to eliminate this deterioration by forming the Pt layer 4 thickly. In that case, Ti/
When patterning the (Pt, Pd, W)/Au electrode, it is difficult to etch only the electrode without etching the semiconductor, and sputter etching leaves damage to the semiconductor substrate. Furthermore, the lift-off method is simple and commonly used for electrode patterning, but it has the disadvantage of poor yield for thick metals.

It is also possible to eliminate this deterioration by reducing the total thickness of the insulating film, but pinholes may easily occur in the surface protective film, and depending on the element, the thickness of the insulating film may have an optimum value. Therefore, the insulating film cannot be made thinner unnecessarily.

As described above, the conventional method for forming electrodes with a multilayer structure has the disadvantage that semiconductor elements tend to deteriorate, reducing reliability.

[Purpose of the invention]

An object of the present invention is to provide a method for forming an electrode for a multilayered semiconductor device, which eliminates the above-mentioned drawbacks, prevents deterioration of the semiconductor device, and improves reliability. [Structure of the Invention] The present invention The method for forming an electrode for a semiconductor device includes the steps of forming an insulating film on a semiconductor substrate and forming a contact window in the insulating film, and depositing a resist film on the insulating film and the window, and forming the window on the inside. a step of forming a large window in the resist film; a step of partially etching the insulating film in the thickness direction using the resist film as a mask to form a stepped portion in the insulating film; The method is characterized by including a step of depositing a multilayer metal on the window and the stepped portion.

Preferably, the multilayer metal layer is composed of at least two metal layers selected from the group consisting of Ti, Pt, Pd, and W, and an Au layer.

〔Example〕

Next, embodiments of the present invention will be described using the drawings.

FIGS. 2(a) to 2(d) are sectional views shown in order of steps for explaining the first embodiment of the present invention.

First, as shown in FIG. 2(a), Kl on the semiconductor substrate 1 is
i! ! IIi & membrane 2 is provided, contact window 8 is opened,
The surface of the semiconductor substrate 10 is exposed. Next, a resist film 10 is deposited on the insulating film 2 and the window 8 , and a groove 9 that is larger than the window 8 and is included inside the window 8 tube is formed in the resist film 10 .

Next, as shown in FIG. 2(b), the produced portion of the insulating film 2 is partially etched in the thickness direction using the resist film 1° as a mask to form a stepped portion 7.

Next, as shown in FIG. 2(C)K, 11 layers 3. Pi layer 4
, Au layers 5 are sequentially deposited to form a multilayer metal layer.

Next, as shown in FIG. 2(d), by removing the resist film 10, 11 layers 3. Both the Pt layer 44 and the Au layer 5 are removed. As a result, the contact window 8K
A three-layer electrode of T i /P t /Au can be formed.

In this way, the steps 6 of the insulating film 2 can be made smaller by only partially thinning the insulating film 2, and the 1M layer 3. A cut portion in step 6 of the Pt layer 4 is not generated, so that penetration of Au atoms during annealing can be prevented and deterioration of the semiconductor element can be prevented.

FIGS. 3(a) to 3(d) are cross-sectional views showing the steps in order to explain the second embodiment of the present invention.

First, as shown in FIG. 3(a), an insulating film 2 is formed on a semiconductor substrate 1, and a contact window 8 is opened. Next, as shown in FIG. 3(b), a resist film 10 is formed. The resist film 10 is coated on the entire surface, and a window 9 including the window 8 inside and larger than the window 8 is formed in the resist film 10 . Then, the exposed portion of the insulating film 2 is partially etched in the thickness direction to form a stepped portion 7.

Next, as shown in FIG. 3(C), a Ti layer 3. Pt layer 4
are sequentially deposited, and the resist film 10t is removed, and at the same time, the Ti layer and Pt layer thereon are removed. A Ti/Pt two-layer electrode can be formed on the window 8 by this lift-off method.

Next, as shown in FIG. 3(d), using a resist film, vapor deposition, and lift-off method, 11 layers 11, Au layers 5
are stacked, T I / P t / T i / A u
Form a four-layer electrode.

In this embodiment, as in the first embodiment, since the step 60 step difference is made small, cutting of the 11th layer 3 and the Pt layer 4 at the step part is less likely to occur. Since Ti1iill and Au/15 are formed with a small area, penetration of Au during annealing is prevented, and therefore deterioration of the semiconductor element can be prevented.

In the above two embodiments, the metal binding material for the electrode is Ti.

Pt, Au, but generally at least two metal layers selected from the group consisting of Ti, Pt, Pd, and W;
It can be configured with a u layer.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to form a multilayer electrode for semiconductor confectionery that prevents deterioration of semiconductor elements and improves reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of a semiconductor device having a conventional Ti/Pt/Au multilayer structure electrode, and FIGS. 2(a) to 2(d) are steps for explaining the first embodiment of the present invention. 3(a) to 3(d) are cross-sectional views shown in the order of steps for explaining the second embodiment of the present invention. 0 1... Semiconductor substrate, 2 ...Insulating film, 3
...Ti layer, 4...Pt layer, 5...
...Au layer, 6...step, 7...
- Step portion, 8.9...Window, 10...Resist film, 11...Tt layer. Agent Patent Attorney Shingo Uchihara ZT￥] Figure 15

Claims (2)

[Claims] (1) A step of forming an insulating film on a semiconductor substrate and forming a contact window in the insulating film, and depositing a resist film on the insulating film and the window, and forming a larger window including the window inside. a step of forming a step in the insulating film using the resist film as a mask;
A method for forming an electrode for a semiconductor device, comprising the step of depositing a multilayer metal layer on the window and step portion of the insulating film. (2) The semiconductor device according to claim H (1), wherein the multilayer metal layer comprises at least four metal layers selected from the group consisting of Ti, Pi, Pd, and W and an Au layer. Method of forming electrodes for use.