CN102243984B

CN102243984B - Method of removing boron spots on chip

Info

Publication number: CN102243984B
Application number: CN 201010168261
Authority: CN
Inventors: 裘立强; 游佩武
Original assignee: YANGZHOU JIELI SEMICONDUCTOR CO Ltd
Current assignee: YANGZHOU JIELI SEMICONDUCTOR CO Ltd
Priority date: 2010-05-11
Filing date: 2010-05-11
Publication date: 2013-05-08
Anticipated expiration: 2030-05-11
Also published as: CN102243984A

Abstract

The invention relates to a method of removing boron spots on a chip, relating to a method of removing boron spots by electrochemistry. The method comprises the following steps of: firstly, preparing a ZnSO4 solution by using deionized water, wherein a mass ratio of deionized water to zinc sulfate in the solution is 5:(0.8-1.2); secondly, preparing an electrolytic tank, wherein a positive electrode of a direct-current source is connected with a molybdenum wire, and a negative electrode of the direct-current source is connected with a copper rod; then, placing the chip at the bottom of the electrolytic tank, wherein a P surface of the chip is upward and is in contact with the molybdenum wire; afterwards, initiating an electrolytic reaction, regulating the voltage of the direct-current source to 10-20V and electric currents of the direct-current source to 0.8-1.8A, separating out air bubbles from the surface of the chip, ending the reaction when the degree of an ampere meter is 0, and taking out the chip; and finally, placing the chip in an HF (Hydrogen Fluoride) solution to be soaked for 5-10 minutes and then washing with clear water. According to the method, an electrochemistry method is used for replacing a sand blasting method to remove the boron spots on the surface of a semiconductor silicon wafer so that device stress is prevented from generating, the lattice defect is avoided, and the electrical property capacity of a diode is improved. The method has the advantage of being capable of reducing the damage on a wafer, reducing the production cost and increasing the production capacity.

Description

A kind of method of removing boron spots on chip

Technical field

What the present invention relates to is a kind of method that electrochemistry is removed the boron spot, is applied to the removal of the rear boron spot of silicon chip diffusion.

Technical background

When the processing silicon chip, need to carry out the PN junction diffusion, form the semiconductor rectifier effect.When carrying out this diffusing procedure, adopt boron paper (diboron trioxide) to be attached to wafer surface, diboron trioxide wherein and pasc reaction form pure boron, make it have the semiconductor rectifier function.But this process unavoidably can form the boron spot.

The boron spot forms mechanism: during diffusion, diboron trioxide and pasc reaction generate pure boron, and reaction equation is as follows

B ₂O ₃+Si----SiO ₂+B

Be Pyrex (Bs at the bond that silicon face forms diboron trioxide and silicon dioxide this moment ₂O ₃) _a(SiO ₂) _bA boron simple substance part that generates diffuses into Si, plays doping; A part is deposited on the faying face of Pyrex and silicon, is combined into alloy with silicon, i.e. boron spot 5 or claim the borosilicate phase, and boron-rich phase, as shown in Figure 2.This layer boron spot is beneficial to spreading, but because it can exert an influence and must remove subsequent handling.

In diode technique, the method for removing the boron spot after diffusion is sand-blast at present, and this method can produce damage greatly to silicon chip, introduces stress and dislocation, electrically brings very large harm for subsequent product.

The way that solves foregoing problems is more single: otherwise the method that reduces blast dynamics and frequency reduces the silicon chip damage.First silicon chip is carried out oxidation processes, then by HF solution, the silicon chip skin glass is eroded, but its CT Cycle Time is long, and can make the diffused surface concentration loss.

Sandblast, the surperficial discontinuity of work piece can produce internal stress.On the one hand, stress is concentrated, and easily causes broken wafers.In addition, due to the existence of stress, when work, can cause the irregular arrangement of the inner crystalline phase of wafer, thereby cause electrical characteristics to reduce.

Summary of the invention

The object of the present invention is to provide the method for the removal boron spots on chip that a kind of controllability is good, technique is simple, production capacity is high.

Technical scheme of the present invention is: at first, with deionized water preparation ZnSO4 solution, solution quality is than being deionized water: zinc sulfate=5: 0.8-1.2; Secondly, prepare electrolysis tank, the anodic bonding molybdenum filament of DC source, negative electrode connects copper rod; Then, described chip is placed in cell bottom, the P of chip faces up and contacts described molybdenum filament; Then, the beginning cell reaction is adjusted to 10-20V with DC source voltage, electric current 0.8-1.8A, the chip surface bubble, to the ammeter number of degrees be 0 o'clock, reaction stops, and takes out chip; At last, chip is inserted the immersion of HF solution rinse with clear water after 5-10 minute, complete.

The present invention prevents stresses of parts with final realization of boron spot on electrochemical process replacement sand-blast removal semi-conductor silicon chip surface, avoids causing lattice defect, improves the effect of diode electrically sexuality.The present invention produces hyperoxia voltinism oxygen by electrochemical method, so the initial reaction stage silicon chip surface can produce superfine little bubble, the boron oxidation in silicon chip surface boron spot.The employing the solution of the present invention can reduce the damage to wafer, can reduce production costs, and can improve the production production capacity.

Description of drawings

Fig. 1 is the structural representation of electrolysis tank of the present invention

In figure, 1 is chip, the 2nd, and electrolysis tank, the 3rd, molybdenum filament, the 4th, copper rod;

Fig. 2 is the schematic diagram of background technology of the present invention

In figure, 5 is boron spots.

Embodiment

At first the present invention, prepares ZnSO4 solution with deionized water as shown in Figure 1, and solution quality is than being deionized water: zinc sulfate=5: 0.8-1.2; Secondly, prepare electrolysis tank 2, the anodic bonding molybdenum filament 3 of DC source, negative electrode connects copper rod 4; Then, described chip 1 is placed in 2 ends of electrolysis tank, the P of chip 1 faces up and contacts described molybdenum filament 3; Then, the beginning cell reaction is adjusted to 10-20V with DC source voltage, electric current 0.8-1.8A, the surperficial bubble of chip 1, to the ammeter number of degrees be 0 o'clock, reaction stops, and takes out chip 1; At last, chip 1 is inserted the immersion of HF solution rinse with clear water after 5-10 minute, complete.

Implementation method of the present invention further illustrates as follows:

1. electrochemical means is removed the principle reaction equation of boron spot:

Negative pole: Zn ²⁺+ 2e ^----the Zn phenomenon: zinc is separated out on the copper rod surface

Anodal: 4OH ^--4e ^----2H ₂O+O ₂Phenomenon: there is Bubble formation on chip (silicon chip) surface

When cell reaction occured, B and Si reaction in the anodal oxygen that produces the hyperoxia voltinism, it and boron spot generated B ₂O ₃And SiO ₂

4B+3O ₂---2B ₂O ₃

Si+O ₂---SiO ₂

Reacted silicon chip HF acid rinse, the oxide of generation namely is eliminated, and just can remove the boron spot.

2. take silicon chip as example, specific operation process is:

1.. with deionized water preparation ZnSO4 solution, solution quality is than being deionized water: zinc sulfate=5: 1

2.. signal source (DC source) output anode is wired to molybdenum filament, and negative electrode is connected with copper rod.

3.. molybdenum filament is taken off from the rinse bath bottom land, silicon chip is positioned under molybdenum filament, P faces up.

4.. signal source transfers to DC power supply, and voltage is transferred to 10-20V, and electric current reaches the 1A left and right, and silicon chip surface observation Bubble formation speed is to react the soonest as excellent.

5.. observation signal source ammeter reading, when electric current was 0A, the silicon chip surface reaction stopped.

6.. with molybdenum filament take off from, take out silicon chip, soak with HF that water rinses after 5-10 minute.

Claims

1. a method of removing boron spots on chip, is characterized in that, at first, prepares ZnSO with deionized water ₄Solution, solution quality is than being deionized water: zinc sulfate=5: 0.8-1.2; Secondly, prepare electrolysis tank, the anodic bonding molybdenum filament of DC source, negative electrode connects copper rod; Then, described chip is placed in cell bottom, the P of chip faces up and contacts described molybdenum filament; Then, the beginning cell reaction is adjusted to 10-20V with DC source voltage, electric current 0.8-1.8A, the chip surface bubble, to the ammeter number of degrees be 0 o'clock, reaction stops, and takes out chip, during described cell reaction, anode produces the oxygen of hyperoxia voltinism, and B and Si reaction in it and boron spot generate B ₂O ₃And SiO ₂At last, chip is inserted the immersion of HF solution rinse with clear water after 5-10 minute, complete.