JPH022646A - Formation of electrode - Google Patents

Abstract

PURPOSE:To obtain the formation means of an electrode in such a manner that its principal metal having a prescribed form consists of Sn by forming a reversal resist pattern layer on Sn and vaporizing Au or an Au-Sn alloy and then, making Au or the Au-Sn alloy have a desired shape by lift-off and thus, causing Sn to be formed into an electrode having the desired shape by using the foregoing metals as a mask. CONSTITUTION:A resist layer 5 having a shape contrary to a desired one is formed on the surface vaporized by Tin 4 of a first layer electrode material and second layer electrode materials 6 and 7 consisting of Au or an Au-Sn alloy are vaporized over the whole face of the above layer 5. After the foregoing second layer electrode materials 6 and 7 on the resist layer 5 and a resist 5 are removed, the precedent Tin 4 is removed selectively by using residual patterns of the second layer electrode materials 6 and 7 as masks. For example, SiO2 2 is formed on Si 1 by thermal oxidation and a layer Cr-Pt-Au 3 is formed. Sn 4 is vaporized on the above layer and then, a shape contrary to the electrode shape of Sn 4 is performed by the resist 5. After that the Au-Sn alloy 6 and Au 7 are vaporized and then, the Au-Sn alloy 6 and an Au electrode 7 are formed by lift-off. Subsequently, Sn 4 other than electrode parts is removed by etching.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for forming electrodes arranged on the surface of a mount (hereinafter referred to as submount) on which a semiconductor device is mounted.

Conventional technology In light emitting diodes and semiconductor lasers used as light sources for optical communications using fibers, in order to efficiently input light into the fiber, the light emitting area is limited by allowing the entire current to flow only in a restricted area.

When the current is completely limited, the current density in that area becomes high, resulting in a large amount of heat generation. For this reason, in light-emitting diodes and semiconductor lasers for optical communications, semiconductor devices such as light-emitting diodes and semiconductor lasers are mounted on materials with good thermal conductivity to improve heat dissipation and prevent temperature rises in the semiconductor devices as much as possible. I'm here. In this case, a low melting point metal such as tin or solder is placed on the surface of the material having good thermal conductivity as a brazing material for bonding the semiconductor device. Such a material with good thermal conductivity, on which electrodes are formed using a low melting point metal, is used as a semiconductor device submount.

Conventionally, this type of submount has had a configuration as shown in FIG. In Fig. 3, 1 is silicon y (Si), 2
is silicon oxide (SiO2), tri-Om (Cr)-platinum (
Pt), gold (person u), 4 is tin (Sn), ryo is gold body U)
It is.

That is, in the conventional device, an electrode was formed by successively depositing Sn4 and Au7 as brazing filler metals on Cr--Pt.mu.U3.

Problems to be Solved by the Invention In such a conventional configuration, an electrode containing Sn is formed over the entire surface of the submount. The Sn-containing electrode is used as a brazing material for mounting a semiconductor device on the top, but if you want to form a functional part other than the electrode as a brazing material on the submount surface, the Sn-containing electrode can be used on the entire surface. It is necessary to form it in a part without any problem. Since Sn is a material that oxidizes very easily, it is generally
is deposited thinly to prevent oxidation. However, during the vapor deposition of Au7 and Sn4, the alloying between Au7 and Sn4 progresses, forming a U/Sn alloy layer. Since this U/Sn alloy is difficult to remove by etching, the entire 5n-Au electrodes (4, 7) cannot be formed into a predetermined shape. Furthermore, if Sn4 is formed into a predetermined shape by photolithography before vapor deposition, the surface of Sn4 will be oxidized during the resist removal process in IJ lithography, making it unsuitable as a brazing material. In this way, in the past, the main metal of a predetermined shape was Sn.
There was a problem in that it was difficult to obtain an electrode with a certain temperature.

The present invention solves these problems and provides a method for forming an electrode in a predetermined shape whose main metal is Sn.

Means for Solving the Problems In order to solve this problem, the present invention first forms a shape that is inverted from the shape to be obtained with a resist after Sn vapor deposition, and then deposits Au or Au containing Sn, and then deposits the resist. MuU containing the above MuU or Sn and resist 6 above (
lift-off) and then MuU containing MuU or Sn
The desired shape is obtained by removing Sni etching except for the remaining portion.

According to the present invention, an electrode having a predetermined shape whose main metal is Sn is covered with Sn with MuU or an Au alloy, and an electrode without oxidation of Sn can be formed.

Embodiment FIG. 1 is a sectional view of a submount formed according to an embodiment of the present invention, and FIG.
FIG. In Figures 1 and 2, 1 is Si, 2 is 5in2.3 is CR-PT-MU, 4 is Sn, 5 is resist, 6 is gold/tin alloy (tin content 12%), and A is It is Au.

Such a submount is manufactured by the following method. As shown in FIG.
00o-containing SiO□2 is formed.

Next, 500 people for Or, 1000 people for PT, 40 people for U.
A layer of 0r-Pt.mu.u3 is formed by continuous vapor deposition to a thickness of 00. 2 μm of Sn4 was vapor-deposited on 0r-Pt・mu3,
Sn4? shown in Figure 1 with resist 5? ! A shape that is inverted from the polar shape is formed. After that, as shown in Figure 2, Mu/S
n combination 4. (Sn content 12%) 1000 people and 2000 people vapor deposited MuU. Then, using the step of the resist 5, the mu u7 on the resist 6, the Au/Sn alloy 6, and the resist 5'! Removed using i-acetone (lift-off)
Then, the input u/Sn of the shape to be obtained as shown in Fig. 2C is
An alloy 6°Au7 electrode is formed. And this person u/
Nitric acid: water: 1:1 using S n alloy 1 U electrode as a mask
Muu/Sn alloy/Sn4 other than the MuU electrode part with a mixed solution of 0
By etching away, a Sn electrode having a shape as shown in FIG. 1 is obtained. By the above method, the desired shape of S
An n-electrode can be obtained.

In addition, in the example, the metal on Sn4 is mu /S n
Although the case of Alloy 6 and Mu7 has been shown, it is clear that the same effect can be obtained with Au2 alone.

Effects of the Invention As described above, according to the present invention, S is used as the main electrode metal.
When using n, first provide an inverted pattern layer of resist on Sn, and then form a layer of mu or k u/S n
Au or Mu is deposited by vapor deposition and lift-off.
/S n alloy into a desired shape and use it as a mask,
By forming an electrode of Sn into a desired shape, an electrode without oxidation of Sn can be easily realized.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a submount formed according to an embodiment of the present invention, Fig. 2 a% O is a cross-sectional view showing the forming method of the present invention in order, and Fig. 3 is a cross-sectional view of a conventional submount. FIG. 1...Silicon (Si), 2...Silicone oxide (sio23...Chromium (Cr), platinum (p)
t)・Gold (MU), 4...Tin (Sn), 6...
...Resist, 6...Gold/Sn
) Alloy, 7... Gold (Au). Name of agent: Patent attorney Toshio Nakao (1 person)

Claims (1)

[Claims] A resist layer having a shape inverted from the desired shape is formed on the tin-deposited surface of the first layer electrode material, and then a second layer electrode material made of gold or gold containing tin is deposited on the entire surface, and then a second layer electrode material made of gold or gold containing tin is deposited on the entire surface. A method for forming an electrode, comprising removing the second layer electrode material and the resist, and then selectively removing the tin using the remaining pattern of the second layer electrode material as a mask.