RU2676222C2 - Method of improving adhesion of indium microcontacts using ultrasound processing - Google Patents

Abstract

FIELD: photo equipment.SUBSTANCE: usage: for the manufacture of indium microcontacts in the matrix photodetectors. Essence of the invention lies in the fact that the method of improving the adhesion of indium microcontacts using ultrasonic processing on semiconductor wafers with BIS readout arrays or photodiode arrays includes the formation of a metal sublayer under indium, the formation of a protective photoresistive mask with windows in places of microcontacts, sputtering of an indium layer, manufacturing indium microcontacts in one of the ways: removing a protective mask with an indium layer around microcontacts (explosion method), forming a mask for etching on an indium layer with subsequent etching of a layer with one of the known methods (chemical etching, ion etching) with the subsequent removal of photoresist layers, while after forming the microcontact system, the plates are processed in an ultrasonic bath for several minutes.EFFECT: technical result: providing the possibility of high adhesion of indium microcontacts and high homogeneity of its values within large arrays.1 cl, 5 dwg

Description

The invention relates to a manufacturing technology of indium microcontacts in matrix photodetectors of infrared radiation and LSI readout of the photo signal.

Currently, a widely used method for the manufacture of hybrid IR MFPs by the method of inverted mounting of photosensitive elements with LSI readout using indium microcontacts.

It is known that some of the methods for making microcontacts are:

- reverse photolithography method (“explosion method”, lift-off) [V.M. Akimov, E.A. Klimanov, V.P. Liseikin, A.R. Mikertumyants, M.V. Sednev, V.V. Sergeev, I.A. Shelobolin On the "explosive" method of manufacturing metallization systems and microcontacts in the LSI for reading the photo signal // Applied Physics, 2010, No. 4; Jutao Jiang, Stanley Tsao et. al .. Fabrication of indium bumps for hybrid FPA applications. Infrared Physics and Technology. 45 (2004) 143-151];

- ion etching method;

- chemical etching method.

There is also a known method of forming high and uniform indium microcontacts by melting in weak acid vapors at a temperature slightly higher than the melting point of indium (~ 170-200 ° C) of previously created microcontacts using one of the above methods [J Jiang, S. Tsao, T.O Sullivan GJ Brawn. Infrared Physics and Technology, 45 (2004), p. l43-151.

All of these methods have the following disadvantage:

when forming indium microcontacts, several operations of deposition of metal layers are performed: the creation of a sublayer for indium (for example, Cr-Ni, V-Al-V, Mo-Au, Ti-TiN and others) and the deposition of an indium layer with the subsequent removal of indium around the microcontacts by various methods above. In this case, metal layers are usually sprayed by various methods: for spraying the sublayer, ion sputtering of the corresponding metal targets is used, and the indium layer is used by thermal evaporation. This circumstance often leads to the impossibility of sequentially spraying all layers in one vacuum unit without depressurization. Depressurization, in turn, can lead to oxidation of the metals of the sublayer, leading to a deterioration in the adhesion of indium microcontacts to the metal sublayer and a significant scatter of its values in multi-element structures.

A known method of manufacturing microcontacts by creating a metal mask on top of a photoresist layer with the subsequent manifestation of this layer [Shelobolin I.A., Liseikin V.P., Klimanov E.A., Sednev M.V., Mikertumyants A.R. A method of manufacturing indium columns. Patent for the invention No. 2419178], adopted as the closest analogue.

The objective of the invention is to create a manufacturing technology of indium microcontacts using the known methods listed above, which allows for high adhesion of indium microcontacts and high uniformity of its values within large arrays.

In this case, the mutual diffusion of indium and the metal of the sublayer is used when ultrasonic vibrations are applied, which leads to the destruction of the oxide layer between the metals and improved adhesion between them.

The technical result is achieved by the fact that on a semiconductor wafer metal plates (sublayer) are made by vacuum deposition to form indium microcontacts, a layer of positive photoresist is applied, on which an indium layer is sprayed through a photo mask with a window pattern under the microcontacts and developed, a mask is formed by photolithography etching indium and etching indium using one of these methods; then the layers of the photoresist are removed and the plate is processed in an ultrasonic bath for several minutes.

In another embodiment, a layer of positive photoresist is deposited on a semiconductor wafer, on which, after exposure through a photo mask with a window pattern for microcontacts and development, metal layers (sublayer) are deposited, and then an indium layer (in another installation or after a time interval), a mask is formed by photolithography for etching indium and etching indium using one of these methods; then the layers of the photoresist are removed and the plate is processed in an ultrasonic bath for several minutes.

The sequence of the process chain of the proposed method is illustrated in FIG. 1-5, where:

in FIG. 1 shows the process of exposing a photoresist through a photomask,

in FIG. 2 shows a heat treatment process for a photoresist;

in FIG. 3 shows the deposition process of indium;

in FIG. 4 shows the process of dissolving a photoresist:

in FIG. 5 shows the process of ultrasonic processing of microcontacts.

The figures show the following elements:

1 - photo template;

2 - photoresist layer;

3 - substrate;

4 - indium.

A method of manufacturing microcontacts is carried out in the following sequence:

- a layer of positive photoresist is applied to a semiconductor wafer with metal pads for indium microcontacts, followed by drying;

- exposure of the photoresist is carried out using a photomask with a given configuration of the contact pads (Fig. 1);

- the manifestation of photoresist in a standard developer for positive photoresist (1% KOH solution) is carried out (Fig. 4);

- a layer of indium of a given thickness is sprayed onto the photoresist mask (Fig. 5).

Next, the formation of indium microcontacts is carried out in one of the ways:

- dissolution of the lower layer of the photoresist with the simultaneous removal of indium (explosion method);

- etching method,

for what:

- a photoresist mask is formed for etching indium;

- indium is etched by one of the known methods (chemical, ionic) to form microcontacts;

- the photoresist is removed in a solution of dimethylformamide or a mixture of dimethylformamide with monoethanolamine, or by plasma-chemical etching in oxygen plasma.

Next, the plate is processed in an ultrasonic bath for several minutes.

Claims (4)

A method for improving the adhesion of indium microcontacts using ultrasonic processing on semiconductor wafers with LSI sensors or photodiode arrays, including the formation of a metal sublayer under indium, the formation of a protective photoresist mask with windows at the points of microcontacts, the deposition of an indium layer, the manufacture of indium microcontacts using one of the following methods: - removing the protective mask with a layer of indium around the microcontacts (explosion method), - the formation of a mask for etching on an indium layer with subsequent etching of the layer using one of the known methods (chemical etching, ion etching), followed by removal of the photoresist layers, characterized in that after the formation of the microcontact system, the plates are processed in an ultrasonic bath for several minutes.

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