CN202473934U

CN202473934U - Diode core structure for rectification diode

Info

Publication number: CN202473934U
Application number: CN2011204037115U
Authority: CN
Inventors: 李治刿; 张剑; 俞建; 李驰明
Original assignee: SICHUAN TAIJING MICROELECTRONICS CO Ltd
Current assignee: SICHUAN TAIJING MICROELECTRONICS CO Ltd
Priority date: 2011-10-21
Filing date: 2011-10-21
Publication date: 2012-10-03
Anticipated expiration: 2021-10-21

Abstract

The utility model relates to the field of semiconductor device, in particular to a diode core structure for a rectification diode. The disclosed diode core structure for a rectification diode comprises from top to down, a N+ layer, a N- layer, a P- layer and a P+ layer, wherein the upper surface of the N+ layer and the lower surface of the P+ layer are respectively provided with an ohmic contact layer. In the process of diode core manufacture, when performing P-zone substance diffusion, a secondary diffusion process is employed, a sour-layer structure, i.e., N+ layer, N- layer, P- layer and P+ layer, is formed on an N-type monocrystalline silicon wafer, and the juncture portion of the N- layer and the P- layer is a PN junction of the diode core. The diode core structure for a rectification diode enables the effective concentration of P-zone carriers to be increased, the alloy quality and solderability of the surface ohmic contact layers to be improved, the contact resistance to be reduced, and the effective current carrying area to be increased. The diode core structure for a rectification diode can be used for manufacturing a high voltage rectification diode.

Description

The rectifier diode tube core structure

Technical field

The utility model relates to semiconductor device, particularly a kind of rectifier diode tube core structure.

Background technology

Semiconductor rectifier diode (being called for short rectifier diode, diode) is the very general electronic device of a kind of application.Rectifier diode is made up of tube core (being called crystal grain again), lead-in wire and coating layer usually, and what wherein have the corresponding function effect is tube core, exactly is PN junction.

The method of traditional manufacturing rectifier diode crystal grain comprises: operations such as chip diffusion, nickel plating, cutting splitting, mesa etch, detection packing.Technological process is following:

1, chip type selecting

General silica-based rectifier diode all is as basic material with N-type monocrystalline silicon.

2, chip diffusion

The two sides that on N-type monocrystalline silicon piece, is coated in silicon chip through paper source or water source is spread 5 valency impurity and 3 valency impurity respectively, forms Open Junction (a kind of PN junction version).

3, make ohmic contact layer

After accomplishing the chip diffusion, carry out metalized,, form ohmic contact layer like nickel plating etc. on the silicon chip two sides.

4, cutting splitting

Draw the benchmark line of cut at the original datum level of silicon chip (111 face) by predetermined angular, i.e. the directing group directrix; Cut into crystal grain through scribing machine by the directing group directrix, and come out die separation through the mechanical separation mode.

5, mesa etch (in the prior art, this operation is carried out after crystal grain has welded lead-in wire, belongs to rectifier diode manufacturing process)

Crystal grain to having welded lead-in wire carries out mesa etch, and the affected layer (about 50 μ m) when removing cutting splitting forms the crystal grain mesa.

6, purged and packed.

Above operation is carried out repeatedly the pure water cleaning and used the chemical dehydration mode to dewater, dry the crystal grain that gets product.

The rectifier diode tube core of this conventional method manufacturing has following shortcoming:

1, the rectifier diode crystal grain of conventional method manufacturing is three-decker, and tube core N district 1 is made up of N+ layer 101 and N-layer 102, and P district 2 is made up of one deck P+ layer 201, and N-layer 102 is tube core PN junction 12 with P+ layer 201 intersection, and is as shown in Figure 1.Because diffusion principle P+ layer 201 impurity can influence ohmic contact layer 200 surface alloy effects toward inner continuation migration, such alloy-layer ohmic contact is bad, influences device electrical performance.

2, the rectifier diode crystal grain mesa of conventional method manufacturing is positive truncated rectangular pyramids shape; Angle=180 between N district 1 and the P district 2 °; As shown in Figure 1, PN junction just in time is in the position of positive truncated rectangular pyramids near bottom surface, when armor coated; This place's coating thickness is little, causes the voltage breakdown fault easily.

The utility model content

The utility model technical problem to be solved just provides a kind of rectifier diode tube core structure, improves the tube core electrical performance indexes.

The utility model solve the technical problem; The technical scheme that adopts is that the rectifier diode tube core structure is characterized in that; Said tube core is made up of top-down N+ layer, N-layer, P-layer and P+ layer, and said N+ layer upper surface and P+ layer lower surface have ohmic contact layer.

In die making's operation of the utility model, when carrying out the diffusion of P district matter, adopt the secondary diffusion technology, on N-type monocrystalline silicon piece, form four-layer structure, i.e. N+ layer, N-layer, P-layer and P+ layer, N-layer and P-layer intersection are the PN junction of tube core.This structure has improved P district charge carrier valid density, and has improved the alloy mass and the solderability of surperficial ohmic contact layer, has reduced contact resistance, and the effective-current area increases.These are for improving device electrical performance, like current density, withstand voltage, power etc. very big benefiting are arranged all.

Further; Said die shape is the assembly of right prism and straightedge platform; Said right prism bottom surface is connected with straightedge platform upper bottom surface, and has identical shapedly and big or small, and its rib docks each other; Said right prism is made up of N+ layer and N-layer from top to bottom, and said straightedge platform is made up of P-layer and P+ layer from top to bottom.

This crystal grain mesa of the utility model is different from prior art is passed through the positive frustum shape of acid etching acquisition behind welding lead grainiess fully, traditional N district, grainiess PN junction place and P district intersection angle=and 180 °, referring to Fig. 1.The maximum place of electric-force gradient when this place is device work; When applying protection, the thickness of this place's coating adhesive is the relatively thinner place of whole coating layer, and this place is easy to form crystal grain edge wedge angle; Cause grain surface to form the spike electric field easily, these all greatly reduce device withstand voltage.There is a depressed area the utility model grainiess N district and P district intersection (being right prism and straightedge platform intersection) angle＜180 °, referring to Fig. 2.When armor coated, coating adhesive flows and concentrates on the depressed area, and coating thickness herein is the thicker place of whole coating layer, and stops grain surface spike electric field phenomenon fully.The protective layer dielectric strength of this structure is superior to traditional crystal grain greatly.

Concrete, said right prism and straightedge platform are respectively four-prism and positive truncated rectangular pyramids.

This structure more meets the crystal form of silicon, helps reducing grain surface spike electric field, improves device withstand voltage.

Further, said ohmic contact layer comprises inner alloy layer and outer layer metal coating.

The ohmic contact layer of this double-layer structure, manufacture craft is ripe, simple, and ohmic contact layer and silica-base material compatibility are good, and in conjunction with tight, contact resistance is little.

The beneficial effect of the utility model is; Adopt the secondary diffusion technology when spreading, form the tube core structure of four-layer structure, improved the alloy mass of surperficial ohmic contact layer in the P district; Reduced contact resistance; Improved solderability, increased effective-current area and P district carrier concentration, tube core current density, withstand voltage, power etc. all improve a lot.The grain shape of the utility model forms before welding lead, can simplify diode manufacturing process, reduces chemical agent use amount in the diode generative process, has reduced the pollution of diode industry greatly.Because just formed table top in the crystal grain manufacturing process, the crystal grain bonding area is littler with respect to traditional crystal grain, has reduced package dimension, helps miniaturization of devices.Because grainiess changes and bonding area reduces, follow-up frock making material consumption reduces, and has reduced the device manufacturing cost.The crystal grain of the utility model is particularly suitable for making the highly reliable diode of high back-pressure low-leakage current.

Description of drawings

Fig. 1 is a prior art tube core structure sketch map;

Fig. 2 is an embodiment tube core structure sketch map.

Among the figure: 1 is the N district; 2 are the P district; 100 is the ohmic contact layer of N+ laminar surface; 101 is the N+ layer; 102 is the N-layer; 12 is PN junction; 202 is the P-layer; 201 is the P+ layer; 200 is the ohmic contact layer of P+ laminar surface.

Embodiment

Below in conjunction with accompanying drawing and embodiment, describe the technical scheme of the utility model in detail.

The rectifier diode tube core of the utility model adopts the secondary diffusion technology during diffusion of impurities in the P district, simultaneously forms P-layer and P+ layer at N-type monocrystalline silicon piece, the four-layer structure of formation entire chip, i.e. N+ layer, N-layer, P-layer and P+ layer.The tube core of this four-layer structure has effectively improved carrier concentration, has improved the alloy mass of the surperficial ohmic contact layer in P district, has reduced contact resistance, has increased the effective-current area.These have very big benefiting for improving device electrical performance.

Embodiment

This routine rectifier diode tube core structure is as shown in Figure 2, and die shape is the assembly of four-prism and positive truncated rectangular pyramids.The four-prism bottom surface is connected with positive truncated rectangular pyramids upper bottom surface, and its joint portion has identical shaped and big or small, and four-prism docks with four ribs of positive truncated rectangular pyramids each other.Four-prism is the N district 1 of tube core, is made up of N+ layer 101 and N-layer 102 respectively from top to bottom, and there is ohmic contact layer 100 on N+ layer 101 surface; Positive truncated rectangular pyramids is the P district 2 of tube core, is made up of P-layer 202 and P+ layer 201 respectively from top to bottom, and there is ohmic contact layer 200 on P+ layer 201 surface.In this example, ohmic contact layer 100 includes inner alloy layer and outer layer metal coating (not shown among Fig. 2) with ohmic contact layer 200.This routine rectifier diode tube core is to spread 5 valency element (like phosphorus) another sides by one side on the N-type monocrystalline silicon piece to spread 3 valency elements (like boron) and form; Spread the N+ layer 101 of 5 valency elements formation tube core; Spread 3 valency elements and adopt the secondary diffusion technology; Diffuse to form for the first time P-layer 202 and diffuse to form P+ layer 201 for the second time, N-layer 102 is a N-type monocrystalline silicon piece bulk material.

Claims

1. the rectifier diode tube core structure is characterized in that, said tube core is made up of top-down N+ layer, N-layer, P-layer and P+ layer, and said N+ layer upper surface and P+ layer lower surface have ohmic contact layer.

2. rectifier diode tube core structure according to claim 1; It is characterized in that said die shape is the assembly of right prism and straightedge platform, said right prism bottom surface is connected with straightedge platform upper bottom surface; And have identical shaped and big or small; Its rib docks each other, and said right prism is made up of N+ layer and N-layer from top to bottom, and said straightedge platform is made up of P-layer and P+ layer from top to bottom.

3. rectifier diode tube core structure according to claim 2 is characterized in that, said right prism and straightedge platform are respectively four-prism and positive truncated rectangular pyramids.

4. rectifier diode tube core structure according to claim 1 is characterized in that, said ohmic contact layer comprises inner alloy layer and outer layer metal coating.