DE1079419B - Solution for etching semiconductor elements - Google Patents

Description

Solution for etching semiconductor elements Semiconductor arrangements, such as Rectifiers, transistors, photodiodes and the like are already used for various Purposes applied in electrical engineering. They mostly consist of one in the The main thing is a single crystal body made of germanium, silicon or an intermetallic Connection of elements of III. and V. Group of the Periodic Table on the Electrodes are applied, for example alloyed.

In known manufacturing processes of such semiconductor arrangements Both the unalloyed semiconductor base bodies and the semi-finished semiconductor elements are used Subjected to etchings. This is mainly used to clean the surface adhering foreign matter as well as the removal of irregularities of the crystal surface. In particular, the outer p-n limits, i.e. H. the places where the p-n junctions come to the surface, be subjected to a polishing etch, so that as possible high reverse voltage is achieved.

So far, known etching liquids have been used for these etchings, for example a mixture of hydrofluoric acid and nitric acid in a ratio of 1: 1. However, treatment with this liquid has various disadvantages. For example it attacks the silicon very violently. It also changes during the etching process their effect, for example as a result of warming and / or the formation of nitrous gases. For these reasons, it is very difficult to precisely dose the ablation. There were Attempts have already been made by diluting the etching liquid, for example using glacial acetic acid to counter these difficulties. Here, however, the Polishing effect, which experience has shown to achieve the highest possible reverse voltage is necessary. This reduction can lead to the complete disappearance of the polishing effect walk. So instead of an improvement, there are new disadvantages.

In order to eliminate these disadvantages, polishing etching of semiconductor elements has been used proposed the use of an etching liquid with silicon base body, the Contains potassium permanganate dissolved in hydrofluoric acid. For example, a solution of 0.5 to 1 g of potassium permanganate in 10 cm³ of 40% hydrofluoric acid can be used.

The etching time for the same ablation as with the previously usual etching liquid (H F + HNO3; 1: 1) is around 100 times as long with the new etching solution. The polishing effect is not noticeably affected. Due to the considerable extension of the Etching duration, an exact dosage of the removal is possible. This is another Advantage connected. Because of the short etching time with the previously known etching liquid up to now, each semiconductor element had to be treated individually, even if this was the case under other circumstances would not have been necessary, for example when etching the raw Semiconductor base body before alloy treatment. In the new etching solution according to the invention can use a larger number of such semiconductor base bodies at the same time be treated. This brings with it a considerable saving of work and time.

By suitable choice of the mixing ratio of the etching solution can can further be achieved that the etching effect after removal of a predetermined amount of silicon stops by itself as a result of exhaustion of the etchant. This brings another Simplification of the procedure, since any monitoring can be omitted.

Claims (1)

PATENT CLAIM: Use of a solution of potassium permanganate in hydrofluoric acid, preferably 0.5 to 1 g of potassium permanganate in 10 em3 40% hydrofluoric acid, for polishing etching of semiconductor elements with a silicon base.