DE1758751A1 - Oven for the diffusion of interference points in semiconductor bodies - Google Patents

Description

"Furnace for. In.funding of imperfections in semiconductor bodies" Die The present invention relates to a furnace, which is particularly useful as a diffusion furnace Diffusion of impurities into the semiconductor body is provided, here there is the invention therein. that on the evacuable pipe of the furnace a lock system connected; with the help of which batches without intermediate ventilation of the pipe in the pipe can be inserted or exchanged for rings located in the pipe.

Most semiconductor components today are made by one-off or several times repeated diffusion of impurities in a semiconductor body produce a certain type of newspaper. This goes for everything for that Components that are manufactured according to the planar principle. For this are special two procedures became known.

In the oldest process, the semiconductor wafers to be diffused are used brought into an open tube of a diffusion furnace, into which a carrier gas stream transported incident material is initiated. This method has the major disadvantage that the furnace interior. after a short period of use is so badly contaminated that reproducible results can no longer be achieved are. Especially when there are low concentrations of impurities on the greedy surface of the diffusing semiconductor wafer are desired, i.e. if the sheet resistance the doped areas should be large, the emitted by the furnace and uncontrollable act Doping substances are very disruptive and distort the desired characteristics of the semiconductor components in an impermissible manner.

To avoid these disadvantages, another known method was developed in which the diffusion is carried out in a sealed and evacuated quartz ampoule. For this purpose, a powder containing the impurity material, for example doped silicon powder, and the semiconductor wafers to be doped are placed in the still open quartz ampoule. The ampoule is then evacuated, sealed vacuum-tight and placed in a furnace tube to the required diffusion temperature. In this method, the impurity concentration on the surface of the diffused regions in the semiconductor wafers is determined by the impurity concentration in the doping powder. This method delivers reproducible results even with low doping concentrations, i.e. high sheet resistances aimed for in the diffused areas, since the quartz ampules are only used for a single diffusion process. However, this makes the diffusion process very expensive. since the pure quartz costs per batch amount to DM "# e : @ .---- to 3öo, --_-. Since each batch consists of approx Semiconductor schebe'-pro Di ffusi: öiisi, i, ozsss a relatively high cost, which * makes the described method inefficient.

In contrast, the new furnace according to the invention enables diffusion processes; which are t i 111g and. all advantages of powder diffusion in quartz ampoules without restriction exhibit. The new furnace has at least one insertion chamber adjacent to the furnace tube on, which can be evacuated separately and via a Szhleusentor with the evacuated Pipe of the furnace connected i.-st. The batches: are made with the help of slides that vacuum-tight to the outside and controllable from the outside, from the Eiüs'h-hbkammer-in the actual stovepipe and then inserted with another shear into the The hot zone of the pipe is conveyed: The batches can, however, also be moved using a motor success-n. - The invention and its advantageous embodiment is described in more detail below with reference to the figure.

The figure shows in longitudinal section a quartz tube 1o of a diffusion furnace, which is surrounded by a heating device and has a hot zone 11, which for Carrying out the necessary diffusion processes heated to approx. 100 to 1200oC will.

The quartz tube 1o is divided into three parts with another Pipe 9 connected. The part of this tube adjacent to the quartz tube consists of one normal diffusion tube, which is connected to the insert = diffusion tube 5. This Pipe part 5 is connected to the two insertion chambers 4 via lock gates 12. Of the last part 13 of the diffusion tube, which connects to the insertion tube, is used for receiving the slide 8, with the help of which the batch 14 is manually or motorized conveyed into the hot zone 11 and out of this zone again after the diffusion process is brought back into the slide-in diffusion tube 5 '' '. The insertion chambers 4 are Over more lock gates 3 accessible from the outside and have more vacuum-tight inserted slide 15, with the help of which the batches 14 through the open Lock gate 12 can be pushed into the push-in diffusion tube 5. The quartz tube lo, and the diffusion pipe 9 are evacuated or ventilated via the connection piece-1, while the insertion chambers 4 have separate connection pieces 2 can be evacuated and ventilated. In the stovepipe and r r1 the insertion chambers slides that are not accessible from the outside can also be enclosed in a vacuum-tight manner are. Then the slide must be made of ferromagnetic material, so that a Displacement from the outside with the help of a magnetic field, for example from a field magnet herriihr, t, possible: is ..

The furnace according to the invention r possible: r-llt a plurality of successive diffusion processes, dit. without intermediate ventilation of the stovepipe. Here, Lu a batch 14 is introduced through the gate 3 into an insertion chamber = with the lock gate 5 closed. Then the gate 3 is closed, the gallery 4 evacuated and the lock gate 5 opened. An approximately in the furnace, and already doped batch is optionally conveyed in a second slot empty chamber and thereafter can be inserted to be diffused batch with the aid of the slide 1 5 in the insertion diffusion tube. 5 The sluice gate 5 is closed again and the batch is conveyed into the hot zone of the pipe 1o with the aid of the slide 13. The batches preferably consist of a plurality. of semiconductor wafers, for example made of silicon, which are accommodated in a container. For this purpose, the panes are set up vertically in a pane holder 6 and placed in the quartz container which already contains the diffusion powder mixed with doping material. This diffusion powder consists, for example, of n- or p-doped silicon material. The container is closed with a quartz lid 7. Since the quartz lid ..7. the batch container is optically tight. man: a quasi-tight diffusion vessel from which no dopants escape into the interior of the pipe. In this way, contamination of the quartz tube 9 with impurities is prevented. With the aid of the furnace according to the invention: the quartz costs are greatly reduced, since the quartz tube is very much. can be used many times. The batch times are very short, as the oven does not need to be ventilated.

Claims (1)

P a t: e n t a r1 s p r ii c h e 1) Oven, especially for diffusion of imperfections in semiconductor bodies; characterized in that the evacuable Pipe of the furnace is connected to a lock system, with the help of which batches without Intermediate ventilation of the: pipe introduced into the pipe or against those located in the pipe Cllärgen are exchanged: 2) Furnace according to claim 1, characterized in that at least one insertion chamber is provided which can be evacuated separately, and that this insertion chamber via a lock gate with the evacuable tube of the furnace connected is. 3) furnace according to claim -1 or 2, characterized in that for Moving the batches in the slide-in chambers and in the vacuum-tight tube: outwardly guided and externally controllable slides are provided. 4) furnace according to claim 1 or 2, characterized in that in the tube and in the Esnschubkammern slide vacuum-tight are angeördnet, which are moved from the outside with the help of a magnetic field. 5) Oven according to claim 1 or 2, characterized in that the batches in the egg waste; and can be moved by a motor in the tube of the furnace. 6) Furnace after a dE: r preceding Claims, characterized in that the batches consist of semiconductor wafers, which are housed in a container closed with a lid, and that, in the container, there is also an F: contain US powder, located. 7) furnace according to claim 6, characterized in that the lid on the container is optically tight.