CS239786B1 - A method of creating a positive image on a photosensitive chalcogenide layer - Google Patents

Abstract

The method of creating a positive image on a photosensitive chalcogenide layer consists in tempering the chalcogenide layer at a temperature greater than Tg - 10 °C before exposure, where Tg is the softening temperature of the layer.

Description

The use of chalcogenide layers in microelectronics is known. Changes in the physico-chemical properties after irradiation of the layer result in a change in the rate of etching in the chemical reagents. An important characteristic of resistors is the ratio of dissolution rates of the irradiated to the non-irradiated part of the layer.

Depending on the method of preparation of the layer and on the type of etching agent, negative and positive behavior of the layer as a resist can be achieved. When exposed to a freshly vaporized layer of, for example, ASjSj composition and using caustic soda, the layer behaves as a negative resist and the ratio of dissolution rate is 1: 5 to 15. Exposure can be performed with white light of sufficient intensity, ultraviolet radiation , accelerated electron or ion beam, or X-rays.

In some cases, however, in the lithography technology, a positive masking process is preferred for microelectronics, where the radiation exposed areas are etched faster than the unlit areas.

A method of forming a positive image on a photosensitive chalcogenide layer having the composition AsS _x , wherein 1.1 < x < 4 according to the invention consists in tempering the layer after steaming at T >

An advantage of the present invention is that in a single steaming process, substrates requiring a positive process with substrates requiring a negative lithographic process can be fired simultaneously.

Fig. 1 shows the change of the negative process to a positive for the AS2S3 composition layer. Figure 2 illustrates the use of the chalcogenide layer as a resist. The curve a in Fig. 1 indicates a negative etching process where the etching rate of the irradiated chalcogenide layer is lower than the etching rate of the unirradiated layer.

KIiyka 'b is a positive process where the etching rate of the irradiated chalcogenide layer is higher than that of the unirradiated layer. The ratio of the two speeds is plotted on the vertical axis.

The use of the chalcogenide layer as a negative and positive resist is shown in Figure 2, where the β-chalcogenide layer for the negative process, i.e. not tempered at a temperature greater than Tg - 10 ° C, the l-chalcogenide layer tempered at a temperature greater than Tg - 10 ° C, £ - SiO layer, £ - semiconductor pad, eg silicon, £ - mask, £ - chalcogenide layer for positive post-exposure process, '£ - chalcogenide layer for negative post-etching process,' '6' - structure of the chalcogenide layer for the positive process after etching, '£,' 7 '- etching of a part of the SiO layer in the negative and positive process and 8,' 8 '- structure of the SiO after removal of the remainder of the chalcogenide layer.

The use of the invention will be explained in the following examples.

He did

In one steaming process, 4 pads were deposited with a 0.6 µm layer of As ₂ S _{3 material} . The samples thus obtained were labeled A, B, C, and D. The A was not tempered prior to etching.

Sample B was tempered at 80 ° C for 30 min., Sample C at 140 ° C for 30 min. And Sample D ₍ at 190 ° C for 30 min. All samples were exposed through a mask containing 5 µm diameter orifices.

After the etching performed in the alkaline etching agent, negative imaging was observed in samples A, B and C. For sample D, which was tempered at 190 ° C, the image was positive, with the etching rate ratio for the unlit part and the lit part 1; The lithographic process, both negative and positive, is shown in Figure 2.

Example 2

Made of AsS material. . the chalcogenide layers were vaporized onto 3 substrates designated J-Z 4 Q Q by A, B and C. The pad A was tempered at 100 ° C, the pad B at 140 ° C and the pad C at 200 ° C.

The halide layers on substrates A and B showed negative imaging after exposure and etching in an alkaline reagent. Sample C showed positive imaging.

Claims (1)

SUBJECT OF THE INVENTION A method of forming a positive image on a photosensitive chalcogenide layer having the composition AsS ^, wherein 1.1 <x ^ 4, characterized in that the chalcogenide layer is tempered at a temperature greater than Tg - 10 ° C before exposure, where Tg is the softening temperature of the layer .