SU653647A1 - Method of forming base source at manufacturing transistor structures - Google Patents

Description

The invention relates to a method of manufacturing transistor structures for ultrafast and low power integrated circuits having micron base sizes and submicron emitter sizes, emitter contact windows.

A known method of forming a base source in the manufacture of transistor structures includes applying a non-uniform coating containing alloying, for example borosilicate glass, shielding, for example aluminosilicate, and masking, for example silicon dioxide, layers and its photolithography.

However, the use of alumina as a dopant is inconvenient, since it is diffused from it in a hydrogen atmosphere. In addition, it screens much worse than some materials (about twenty times worse than the aluminosilicate layer). In this case, the width of the emitter window depends on the accuracy of combining the photomask with the plate. Since the coincidence error is not less than ± 0.5 (error of the alignment settings), such a spread across the window width is unacceptable when receiving windows of submicron size.

The aim of the invention is to obtain self-matching emitter windows with a base region, base and emitter contact windows of submicron sizes.

This is achieved by applying a shielding and masking layer of an inhomogeneous coating onto the semiconductor plate with a doping layer, forming a second masking layer, forming a protective relief from the photoresistor and placing the plate into an etchant that dissolves only the second masking layer, then etching the first masking and shielding layer To the doping layer with an etchant, dissolving both layers at the same speed and not affecting the second mask layer, transverse etching of the control layer to the specified dimensions is performed, see Put a photoresist and etch the alloying layer to the silicon surface with an etchant, dissolve the alloying, shielding and masking layers at the same rate, remove the second masking layer.

FIG. I is given a plate with a non-uniform coating, on which a relief of photoresist is formed; in fig. 2 - semiconductor wafer before cross etching; in fig. 3 - semiconductor wafer after transverse etching of the control layer and removing the photoresist; in fig. 4 - semiconductor wafer after etching the alloying layer; in fig. 5 - formed base source after removal of the second masking layer.

When forming the base sources of the proposed method, a non-uniform coating consisting of an alloying layer 2, for example borosilicate glass, a shielding layer 3, for example an aluminosilicate, a masking layer 4, for example silicon dioxide, is formed on the semiconductor plate 1 (see Fig. 1). Layers of non-uniform coating are applied by low-temperature methods.

A second masking layer 5 is applied to the formed coating, which is not dissolved in the etchers of the non-uniform coating, for example molybdenum or aluminum. Layers of non-uniform coating should also not be dissolved in the etchant of the second control layer. A layer of photoresistor 6 is applied onto the plate prepared in this way, a protective relief of the required pattern is formed, after which a second masking layer 5, for example molybdenum, is etched in an etchant consisting of 14 vol. including concentrated orthophosphoric acid, 7 vol. including glacial acetic acid and 1 vol. including deionized water. Masking layer 4 and shielding layer 3 are etched at approximately the same speed as the alloying layer, for example, in an O-etchant consisting of 1 vol. including concentrated hydrofluoric acid, 3 ob.h. glacial acetic acid and 25 vol. h. 1 ° / o-tion of an aqueous solution of oxalic acid. The structure shown in FIG. 4. In a further transverse etching, the dimensions of the regulating layer are adjusted to the specified, as mentioned above. After that, one of the known methods is used to remove the photoresist, to obtain the structure shown in FIG. 3, and the plate is openly etched in the P-Etchant, dissolving with the same speed, masking 4, shielding 3 and alloying 2 layers. Etching continues until the unprotected areas of the alloying layer are removed. Since the etching rates of layers 2, 3, 4 are the same, during this time the masking layer from the part of the structure that is not covered by the control layer is released. The mask layer acquires the dimensions of the control layer and the structure shown in FIG. 6. After that, the regulating layer is removed and the base source is obtained, in which the alloying and shielding layers have the same dimensions, and the shielding of the protective layer is smaller by a predetermined amount (see Fig. 5).

The proposed method of forming a base source for manufacturing transistor structures provides self-aligning emitter windows, contact base windows and an emitter of micron and submicron dimensions, where the width of the emitter window does not depend on the window size in the photomask, but on the time of transverse etching of the control layer.

In addition, obtaining self-compatible submicron-sized windows does not require new equipment, but is carried out using standard equipment for contact photolithography.

Claims (5)

1. A method of forming a base source in the manufacture of transistor structures, comprising applying a non-uniform coating containing alloying, for example borosilicate glass, shielding, for example aluminosilicate, and masking, for example silicon dioxide, layers, its photolithography, characterized in that, in order to obtain self-aligning windows emitter with a base area, contact windows of the base and an emitter of submicron size, a second masking layer is applied to the semiconductor wafer with a non-uniform coating the relief from the photoresistor and place the plate in the etchant, dissolving only the second masking layer, then etching the first masking and shielding layers to the alloying layer with an etchant, dissolving both layers at the same speed and not affecting the second masking layer, transverse etching of the second masking layer to a predetermined size, remove the photoresist and etch the alloying layer to the surface of the silicon with an etchant, dissolve the alloying, shielding and first masking layers at the same rate, then Avitel without affecting the other layers are removed second masking layers. 2. A method according to claim 1, characterized in that the second masking layer is aluminum. 3. A method according to claim 1, characterized in that the second masking layer is molybdenum. 4. Method according to paragraphs. 1 and 3, characterized in that after the formation of a protective relief, molybdenum is etched in P-etchant to silicon dioxide, washed with water, silica and aluminosilicate are etched in O-etchant, Mo is cross-etched, the photoresistor, P- Borosilicate glass is etched and molybdenum is removed. 5. A method according to claim 4, characterized in that the O-etchant consists of 1 vol. including concentrated hydrofluoric acid, 3 vol. including glacial acetic acid and 25 vol. including 1% aqueous solution of oxalic acid