Method for manufacturing electrical solid state devices utilizing shadow masking and ion-implantation

Claim 1

A method of manufacturing an electrical solid state device having a stratum presenting a surface at which the stratum is to be subjected to an implantation treatment, which method comprises the steps of: (i) forming a film on the said surface, the material of the film being doped with ions of a substance to be diffused in the stratum; (ii) covering the film with a layer of a photo-resist; (iii) photographically exposing a trace of at least one channel on the layer, and removing the exposed resist from the trace to leave at least one channel having walls constituted by defined edges of photo-resist and a floor of film material; (iv) forming a trough in the film material by introducing an etchant into each channel whereby an etching action is started on the film material at the floor of the said channel, which action continues through the film thickness until such time as said surface is exposed over a width equal to the width between said defined edges, an incidental action taking place during this time at the walls of the trough which incidental action is deliberately continued after the expiration of said time for a period during which the trough walls are caused to recede and to assume a profile dependent partly on the period duration and partly on the film thickness, the recession of a wall forming at the floor of the trough a margin at which said surface is uncovered and which is overhung by photo-resist; (v) bombarding said surface, from a source above the said surface and the photo-resist, with ions of a substance to be implanted in the stratum, whereby the uncovered nonoverhung stratum undergoes implantation by the bombarding ions; and (vi) heating the stratum and the surviving film material whereby, firstly ions of the dopant substance are transferred from the film material to the stratum and are implanted therein, and secondly ions, implanted either by bombardment or by transfer, are caused to diffuse into the stratum except at said margin where no implanted ions will be present, thereby forming in the stratum a number of individual diffusions of the same type, any two of which are separated from each other by a boundary wall of stratum material whose width of is the width of a margin.

Claim 2

A method of manufacturing an electrical solid state device having a stratum presenting a surface at which the stratum is to be subjected to an implantation treatment, which method comprises the steps of: (i) forming a film on the said surface, the material of the film being doped with ions of a substance to be diffused in the stratum; (ii) covering the film with a layer of a photo-resist; (iii) photographically exposing a trace of at least one channel on the layer, and removing the exposed resist from the trace to leave at least one channel having walls constituted by defined edges of photo-resist and a floor of film material; (iv) forming a trough in the film material by introducing an etchant into each channel whereby an etching action is started on the film material at the floor of the said channel, which action continues through the film thickness until such time as said surface is exposed over a width equal to the width between said defined edges, an incidental action taking place during this time at the walls of the trough which incidental action is deliberately continued after the expiration of said time for a period during which the trough walls are caused to recede and to assume a profile dependent partly on the period duration and partly on the film thickness, the recession of a wall forming at the floor of the trough a margin at which said surface is uncovered and which is overhung by photo-resist; (v) bombarding said surface, from a source above the said surface and the photo-resist, with ions of a substance to be implanted in the stratum, whereby the uncovered nonoverhung stratum undergoes implantation by the bombarding ions; and (vi) heating the stratum and the surviving film material whereby, firstly ions of the dopant substance are transferred from the film material to the stratum and are implanted therein, and secondly ions, implanted either by bombardment or by transfer, are caused to diffuse into the stratum except at said margin where no implanted ions will be present, thereby forming in the stratum a number of individual diffusions of the same type, any two of which are separated from each other by a boundary wall of stratum material whose width of is the width of a margin.