Background technology
High power device due to the electric current that passes through in the course of the work very big, the defect of minute quantity just likely causes the inefficacy of device, therefore in its manufacture process, very high to raw-material quality requirement.If raw material surface exists more defect, will cause that device creepage is excessive, blocking voltage is too low.Therefore, after silicon single crystal bar is cut into silicon single crystal disk, must meticulous grinding be carried out, also need after grinding to carry out chemical corrosion, to remove the defect of abradant surface further.Silicon single crystal wafer grinding process is extremely harsh to the requirement of milling apparatus, should ensure that silicon single crystal disk does not exist open defect in surface after grinding, ensure that the THICKNESS CONTROL of silicon single crystal disk has higher precision again, in general, thickness deviation between silicon single crystal disk is less than ± and 10 microns, therefore, the cost of this kind equipment is very expensive, causes production cost very high.
A kind of manufacture method of traditional power rectifier pipe tube core comprises: at silicon wafer surface pre-deposition aluminium impurity; Carry out aluminium impurity at the yin, yang pole-face of described silicon wafer and deeply tie diffusion; One side mill is carried out to remove unnecessary PN junction to the cathode plane of described silicon wafer; At silicon wafer surface pre-deposition phosphorus impurities; Phosphorus impurities diffusion is carried out at the cathode plane of described silicon wafer; Boron impurity diffusion is carried out at the anode surface of described silicon wafer; Aluminium lamination evaporates; Alloying; Die-size cuts; Table top moulding and protection; Irradiation.In above-mentioned manufacture process, aluminium pre-deposition technique is adulterated at the aluminium impurity that silicon wafer two-sided formation junction depth is very shallow, junction depth is less than 3 microns usually, carry out aluminium impurity depth-diffusion process immediately afterwards, positive-negative-positive vertical structure can be formed in silicon wafer, PN junction depth is some tens of pm extremely micron up to a hundred, needs to adopt one side grinding process to remove the unnecessary PN junction of chip cathode plane, makes silicon chip form PN type vertical structure.
But, the one side grinding process adopted in above-mentioned manufacture method can cause silicon wafer surface to occur a large amount of defect or fine crack, defect can cause that power rectifier pipe tube core leakage current is bigger than normal, reverse BV is on the low side, reduce the rate of finished products of tube core, in the tube core course of work, fine crack, expanding with heat and contract with cold under effect effect and can constantly increasing, finally causes component failure, reduces the long-term reliability of tube core.
Summary of the invention
For solving the problem, the invention provides a kind of manufacture method of power rectifier pipe tube core, the generation of silicon wafer blemish and fine crack can be avoided, thus rate of finished products and the long-term reliability of power rectifier pipe tube core can be improved.
The manufacture method of a kind of power rectifier pipe tube core provided by the invention, comprising:
At least one side of silicon wafer is marked;
The doping of aluminium impurity is carried out by aluminium pre-deposition technique on described silicon wafer surface;
The cathode plane of described silicon wafer is corroded, removes the aluminium impurity of the cathode plane of described silicon wafer;
Carry out aluminium impurity at described silicon wafer anode surface and deeply tie diffusion.
Preferably, in above-mentioned manufacture method, the minimizing technology of the aluminium impurity of the cathode plane of described silicon wafer is:
Protecting glue is utilized to form protection to the anode surface of described silicon wafer;
Corrosive liquid is utilized to remove the aluminium impurity of the cathode plane of described silicon wafer;
Remove described protecting glue.
Preferably, in above-mentioned manufacture method, the removal degree of depth of the aluminium impurity of the cathode plane of described silicon wafer be 5 microns to 10 microns, comprise endpoint value.
Preferably, in above-mentioned manufacture method, described corrosive liquid is acid corrosion liquid or caustic corrosion liquid.
Preferably, in above-mentioned manufacture method, described protecting glue is photoresist.
Preferably, in above-mentioned manufacture method, the anode surface of described silicon wafer or cathode plane are marked.
Preferably, in above-mentioned manufacture method, laser marking or machinery method of carving characters is utilized to mark at least one side of described silicon wafer.
Preferably, in above-mentioned manufacture method, the method for carrying out the doping of aluminium impurity by aluminium pre-deposition technique on described silicon wafer surface is:
Described silicon wafer is cleaned and dries;
Vacuum aluminum pre-deposition diffusion furnace is utilized to carry out the doping of aluminium impurity on described silicon wafer surface.
Preferably, in above-mentioned manufacture method, the method that the aluminium impurity of described silicon wafer anode surface ties diffusion is deeply:
Described silicon wafer is cleaned and dries;
Utilize aluminium to advance technique diffusion furnace to carry out aluminium impurity to described silicon wafer anode surface and deeply tie diffusion.
Known by foregoing description, in the manufacture method of a kind of power rectifier pipe tube core provided by the invention, first at least one side of silicon wafer is marked, to make anode surface and the cathode plane that can distinguish silicon wafer in workflow, then the doping of aluminium impurity is carried out on described silicon wafer surface by aluminium pre-deposition technique, now the diffusion depth of aluminium impurity is more shallow, again the cathode plane of described silicon wafer is corroded, remove the aluminium impurity of the cathode plane of described silicon wafer, then carry out follow-up aluminium impurity depth-diffusion process.So just effectively avoid the processing step of one side mill, thus avoid the generation of silicon wafer blemish and fine crack, thus rate of finished products and the long-term reliability of power rectifier pipe tube core can be improved.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
The manufacture method of a kind of power rectifier pipe tube core that the embodiment of the present application provides as shown in Figure 1, the schematic diagram of the manufacture method of a kind of power rectifier pipe tube core that Fig. 1 provides for the embodiment of the present application.The method comprises the steps:
S1: at least one side of silicon wafer is marked;
Owing to no longer including the step of one side mill in the embodiment of the present application, therefore antianode face can not be come with the surperficial polishing scratch situation of silicon wafer again and cathode plane is effectively distinguished, therefore, need before size cutting, to take measures the cathode plane of tagging chip and anode surface, marked, for follow-up work brings convenience by writing the methods such as mark on aluminium electrode.
S2: carry out the doping of aluminium impurity by aluminium pre-deposition technique on described silicon wafer surface;
In this step, aluminium pre-deposition technique is adulterated at the aluminium impurity that silicon wafer two-sided formation junction depth is very shallow, and junction depth is less than 3 microns, therefore more easily removes.It should be noted that, step S1 and step S2 can exchange, and that is, the process of mark all can not have an impact to the present embodiment before or after can being arranged in aluminium impurity doping process.
S3: corrode the cathode plane of described silicon wafer, removes the aluminium impurity of the cathode plane of described silicon wafer;
Because the junction depth of the aluminium impurity doping of step S2 generation is very shallow, therefore, the aluminium impurity of less thickness only need be removed in this step, greatly reduce the difficulty of removal, and surface characteristic and the evenness of silicon wafer can not be affected, what is more important, so just can be removed by the mode of corrosion, thus would not there is the defect that one side grinding belt comes or crackle in silicon chip surface, thus the excellent electrology characteristic of power rectifier pipe tube core can be ensured, improve rate of finished products and the long-term reliability of power rectifier pipe tube core.
S4: carry out aluminium impurity at described silicon wafer anode surface and deeply tie diffusion.
In this step, aluminium impurity is advanced into design junction depth, wherein, this design junction depth is determined according to chip voltage grade, also along with oxidizing process in the process that this aluminium impurity advances, at the certain thickness silicon dioxide layer of silicon wafer superficial growth, this silicon dioxide layer can as the masking layer of subsequent technique.
In the manufacture method of a kind of power rectifier pipe tube core that above-described embodiment provides, first at least one side of silicon wafer is marked, to make anode surface and the cathode plane that can distinguish silicon wafer in workflow, then the doping of aluminium impurity is carried out on described silicon wafer surface by aluminium pre-deposition technique, now the diffusion depth of aluminium impurity is more shallow, again the cathode plane of described silicon wafer is corroded, remove the aluminium impurity of the cathode plane of described silicon wafer, remove the degree of depth more shallow, then carry out follow-up aluminium impurity depth-diffusion process.So just effectively avoid the processing step of one side mill, thus avoid the generation of silicon wafer blemish and fine crack, thus rate of finished products and the long-term reliability of power rectifier pipe tube core can be improved.
In above-mentioned manufacture method, the minimizing technology of the aluminium impurity of the cathode plane of described silicon wafer can be preferably:
Protecting glue is utilized to form protection to the anode surface of described silicon wafer;
Corrosive liquid is utilized to remove the aluminium impurity of the cathode plane of described silicon wafer;
Remove described protecting glue.
Above-mentioned preferred version can remove the aluminium impurity of cathode plane when antianode face forms available protecting.
In above-mentioned manufacture method, the removal degree of depth of the aluminium impurity of the cathode plane of described silicon wafer can be preferably 5 microns to 10 microns, comprises endpoint value.Reach some tens of pm even the one side mill method of up to a hundred microns relative to the removal degree of depth of the prior art, this method can select thinner silicon wafer to make power rectifier pipe tube core, and the cost of raw material of saving can reach about 15%.
In above-mentioned manufacture method, described corrosive liquid can be preferably acid corrosion liquid or caustic corrosion liquid, and described protecting glue can be preferably photoresist.This makes it possible under antianode face forms the prerequisite of effective protection, the aluminium impurity in target face carries out effectively removing fast, increases work efficiency.
In above-mentioned manufacture method, can preferably mark the anode surface of described silicon wafer or cathode plane.As long as appoint rule in advance, can effectively distinguish the anode surface of silicon wafer and cathode plane.In addition, laser marking or machinery method of carving characters preferably can be utilized to mark at least one side of described silicon wafer, this makes it possible to make mark more obvious, be convenient to identify.
In above-mentioned manufacture method, carrying out the doping of aluminium impurity on described silicon wafer surface by aluminium pre-deposition technique can be preferably:
Described silicon wafer is cleaned and dries;
Vacuum aluminum pre-deposition diffusion furnace is utilized to carry out the doping of aluminium impurity on described silicon wafer surface.
In above-mentioned manufacture method, the method that the aluminium impurity of described silicon wafer anode surface ties diffusion deeply can be preferably:
Described silicon wafer is cleaned and dries;
Utilize aluminium to advance technique diffusion furnace to carry out aluminium impurity to described silicon wafer anode surface and deeply tie diffusion.
It should be noted that; in the method making power rectifier pipe tube core; after the above step; also comprise the steps such as phosphorus pre-deposition, phosphorus propelling, boron diffusion, aluminium lamination evaporation, alloying, die-size cutting, table top moulding protection and irradiation; because these steps are consistent with step of the prior art, therefore repeat no more.
Known by foregoing description, utilize said method, the generation of silicon wafer blemish and fine crack can be avoided, thus rate of finished products and the long-term reliability of power rectifier pipe tube core can be improved, in addition, can also production cost be reduced.
To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.