CN110610872B - Quality detection method of silicon wafer alkali polishing additive - Google Patents
Quality detection method of silicon wafer alkali polishing additive Download PDFInfo
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- CN110610872B CN110610872B CN201910933314.XA CN201910933314A CN110610872B CN 110610872 B CN110610872 B CN 110610872B CN 201910933314 A CN201910933314 A CN 201910933314A CN 110610872 B CN110610872 B CN 110610872B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
- H01L22/24—Optical enhancement of defects or not directly visible states, e.g. selective electrolytic deposition, bubbles in liquids, light emission, colour change
Abstract
The invention relates to the technical field of alkali polishing in photovoltaic cell manufacturing, in particular to a quality detection method of a silicon wafer alkali polishing additive. The quality detection method of the silicon wafer alkali polishing additive realizes quality detection by measuring the pH value of the alkali polishing additive, and comprises the following steps: (1) measuring the pH value of the alkali polishing additive by using a precision measuring instrument; (2) analyzing the measured pH value, judging whether the quality of the alkali polishing additive is qualified or not, and carrying out corresponding treatment, wherein the judgment standard is as follows: when the pH value is more than or equal to 3.50 and less than or equal to 6, the product is qualified; when the pH value is more than or equal to 3.00 and less than 3.50, the production failure of the product is increased and the use is limited; when the pH value is less than 3.00 and is more than 6, the product is abnormal and the library is removed. The invention provides a method for detecting whether the quality of an additive is qualified or not by testing the pH value of the additive according to the components and the working principle of the additive and combining practical application.
Description
Technical Field
The invention relates to the technical field of alkali polishing in photovoltaic cell manufacturing, in particular to a quality detection method of a silicon wafer alkali polishing additive.
Technical Field
And in the photovoltaic cell manufacturing process, etching is needed after double-sided texturing and single-sided diffusion. Leaving the front surface of the single-side diffusion texturing surface, and polishing the textured surface and the diffusion layer on the other surface and the thin side edge to leave a good PN junction on the front surface and an insulating side edge and a flat polished surface on the back surface to reduce the surface recombination rate and create a foundation for film coating, laser windowing and screen aluminum back field formation and good back passivation.
HNO3The acid polishing system of + HF + water has a polishing effect, but has high pollution discharge treatment cost and is difficult to treat, and the acid polishing system does not meet the current national environmental protection requirement. In the actual production, the alkali liquor containing a certain amount of additive is added to polish and etch, so that the cost is low and the environment is protected. The additive mainly comprises a buffering agent, a high-efficiency promoter and a defoaming agent. The additive acts in alkali polishing: the additive contains hydrophilic matter, which forms good contact with the diffusion surface with silicon dioxide to block or slow the front reaction, the back surface helps to defoam, and the reaction rate of alkali and silicon is higher than that of silicon dioxide, namely the additive acts to slow or block the front reaction in alkali polishing to accelerate the back reaction, thereby achieving the polishing effect.
The alkali polishing effect of the additive added in the production is poor: 1. poor edge etching results in short-circuiting of the PN junction sides. 2. The back etching and polishing are uneven, the normal area is flat, and the suede residue exists in the abnormal area. And (3) process analysis and survey results: a is due to an additive incoming material failure anomaly; b, the additive is ineffective due to the factors of long storage time or environmental temperature, exposure and the like, so that poor production is caused.
It is important how to achieve rapid detection of the quality of the additive to ensure proper production.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a quality detection method of a silicon wafer alkali polishing additive. The invention discloses a method for detecting whether the additive is normal by using a pH meter to test the pH value of the additive according to the components and the working principle of the additive and by combining practical application. Only when the pH value is measured to be within the qualified range, the materials can be fed for production; and controlling feeding and storage through the tested pH value.
In order to solve the technical problems, the invention adopts the technical scheme that: a quality detection method of a silicon wafer alkali polishing additive is characterized by comprising the following steps:
a quality detection method of a silicon wafer alkali polishing additive realizes quality detection by measuring the pH value of the alkali polishing additive, and comprises the following steps:
(1) measuring the pH value of the alkali polishing additive by using a precision measuring instrument;
(2) analyzing the measured pH value, judging whether the quality of the alkali polishing additive is qualified or not, and carrying out corresponding treatment, wherein the judgment standard is as follows:
when the pH value is more than or equal to 3.50 and less than or equal to 6, the product is qualified;
when the pH value is more than or equal to 3.00 and less than 3.50, the production failure of the product is increased and the use is limited;
when the pH value is less than 3.00 and is more than 6, the product is abnormal and the library is removed.
The alkali polishing additive comprises a buffering agent, a high-efficiency promoter and a defoaming agent.
The alkali polishing additive comprises sodium sulfate as a buffering agent, a high-efficiency accelerator, namely nonylphenol anionic surfactant, and weak acid salt as a defoaming agent.
The pH value of the alkali polishing additive is accurately measured by a pH meter.
Compared with the prior art, the invention has the following advantages:
the patent aims to solve the problem that the failure can not be rapidly judged due to the failure abnormity of the incoming materials of the additive, the storage for a long time or the ambient temperature and the decomposition of the exposure component, so that the poor production is caused. The detection principle of the invention is as follows: normally the pH value of the additive is fixed, but the defoaming agent in the additive is a weak acid salt, is unstable and slowly decomposes (the decomposition is accelerated by the increase of temperature), and the H in the solution is increased along with the increase of storage time+The concentration increases, the additive solution is acidified, the pH value decreases, and the function of the additive is weakened until the additive is ineffective.
The invention realizes the detection of the quality of the alkali polishing additive by detecting the pH value of the additive by using a small portable pH meter, is simple, portable and easy to operate, is more intuitive compared with pH test paper, can quantize data and is convenient to establish standards.
Drawings
FIG. 1 shows EL imaging of an alkaline polished cell plate when the pH value of the additive is 3.50-6.
FIG. 2 is a scanning electron microscope image of an alkali polished silicon wafer when the pH value of the additive is not less than 3.50 and not more than 6.
FIG. 3 is an EL image of an alkaline polished cell plate when the pH value of the additive is 3.00-3.50.
FIG. 4 is a scanning electron microscope image of an alkali polished silicon wafer when the pH value of the additive is 3.00-3.50.
FIG. 5 is an EL image of an alkaline polished cell plate at pH of additives of pH < 3.00 or pH > 6.
FIG. 6 is a scanning electron microscope image of an alkaline polished silicon wafer at pH < 3.00 or pH > 6 for additives.
Fig. 7 is a schematic structural diagram of the device for measuring the pH value of the alkaline polishing additive according to the present invention.
Detailed Description
The present invention is described in detail below with reference to specific examples, which will assist those skilled in the art in further understanding the present invention, but are not intended to limit the present invention in any way. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Example 1
A quality detection method of a silicon wafer alkali polishing additive comprises the following steps:
(1) the PH of the freshly purchased solution of the alkaline polishing additive was measured using a SMART SENSOR brand PH818 PH meter:
a. cleaning a probe of the pH meter by using distilled water, draining the water of the probe, calibrating the pH meter, inserting the probe into a beaker filled with additives after calibration, ensuring that the probe is positioned below the liquid level, pressing an ON key by a thumb, pressing once again after the numerical value is stable, and recording the numerical value;
b. placing probes at different positions of the liquid level to measure the pH value of the alkali polishing additive for three times, and taking an average value;
the alkali polishing additive is a sharp alkali polishing additive and mainly comprises the following components: sodium sulfate as buffering agent to stabilize the pH value of the solution; the nonyl phenol anionic surfactant can change the surface tension of the solution, so that the solution can be better and more uniformly contacted and reacted with silicon; the weak acid salt generates hydrogen bubbles to be attached to the silicon surface when alkali reacts with silicon for polishing, the contact reaction of alkali liquor and silicon is prevented, the silicon wafer is polished to be uneven, and the defoaming agent can accelerate the bubbles to overflow, so that the solution and the silicon are contacted and reacted uniformly.
Example 2
In this example, the same alkaline polishing additive as in example 1 was used after purchasing and standing for 3 months.
Example 3
In this example, the same alkaline polishing additive as in example 1 was used after purchase and left to stand for 6 months.
Example 4
This example used the same alkaline polishing additive as in example 1, which was purchased and left to stand for 12 months.
Examples 1-4 the alkaline polishing additives pH values are tabulated below, see table 1:
table 1 examples 1-4 pH values of alkaline polishing additives
| Additive for different storage times | New purchasing liquid | Standing for 3 months | Standing for 6 months | Standing for 12 months |
| pH value | 3.64 | 3.50 | 3.12 | 1.96 |
It can be seen from table 1 that the pH values of the additives are different at different storage times, and the pH value of the additive gradually decreases and the acidity increases as the storage time increases.
The electrical properties of the cells treated with the alkaline polishing additive of examples 1, 3 and 4 were analyzed and the results are shown in tables 2-4.
Table 2 electrical properties of freshly purchased alkali polished cell pieces treated with alkali polishing additive
| Open circuit voltage | Short circuit current | Series resistance | Parallel resistor | Fill factor | Photoelectric conversion efficiency | Reverse 14.5V leakage current |
| 0.662V | 9.426A | 0.00163Ω | 506.66Ω | 80.33％ | 20.39％ | 0.466A |
Table 3 electrical properties of alkaline polishing cells treated with alkaline polishing additive standing for 6 months
| Open circuit voltage | Short circuit current | Series resistance | Parallel resistor | Fill factor | Photoelectric conversion efficiency | Reverse 14.5V leakage current |
| 0.659V | 9.361A | 0.00123Ω | 533.945Ω | 80.269％ | 20.18％ | 0.55323A |
Table 4 electrical properties of alkaline polishing cells treated with alkaline polishing additive standing for 12 months
| Open circuit voltage | Short circuit current | Series resistance | Parallel resistor | Fill factor | Photoelectric conversion efficiency | Reverse 14.5V leakage current |
| 0.638V | 9.161A | 1.164Ω | 116.696Ω | 80.04％ | 19.05％ | 0.88A |
According to production statistics, when the pH value of the additive is not less than 3.50 and not more than 6, the alkaline polished wafer EL (electroluminescence infrared) image is bright, and is shown in figure 1, and the alkaline polished wafer is imaged by a scanning electron microscope, and the surface is flat, and is shown in figure 2.
When the pH value of the additive is more than or equal to 3.00 and less than 3.50, the alkaline polished silicon wafer EL is imaged, the image is dark, as shown in figure 3, the alkaline polished silicon wafer is imaged by a scanning electron microscope, and pits are formed on the surface, as shown in figure 4.
When the pH value of the additive is less than 3.00 or more than 6, the alkaline polished cell EL images, the images are blackened seriously, as shown in figure 5, the alkaline polished silicon wafer is imaged by a scanning electron microscope, and the surface of the alkaline polished silicon wafer is provided with a residual pit suede, as shown in figure 6.
Analysis of the data shows that as the pH value of the additive solution is reduced, the alkali polishing effect is poor, the EL image is seriously blackened, the silicon wafer texture is polished to be uneven, and the efficiency of the electrical property, current and voltage filling factor is reduced. Through the data analysis of tables 2-4, it can be seen that as the storage time of the alkali polishing additive increases, the pH value of the solution decreases, the open-circuit voltage, the short-circuit current, the fill factor and the photoelectric conversion efficiency of the battery piece treated by the solution decrease, the resistance value and the reverse 14.5V leakage current increase, and the electrical performance of the battery piece decreases.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof, and thus, the present embodiments are to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (4)
1. A quality detection method of a silicon wafer alkali polishing additive is characterized in that the quality detection is realized by measuring the pH value of the alkali polishing additive, and comprises the following steps:
(1) measuring the pH value of the alkali polishing additive by using a precision measuring instrument;
(2) analyzing the measured pH value, judging whether the quality of the alkali polishing additive is qualified or not, and carrying out corresponding treatment, wherein the judgment standard is as follows:
when the pH value is more than or equal to 3.50 and less than or equal to 6, the product is qualified;
when the pH value is more than or equal to 3.00 and less than 3.50, the production failure of the product is increased and the use is limited;
when the pH is less than 3.00 and more than 6, the product is abnormal and the warehouse is removed;
the alkaline polishing additive comprises a defoaming agent, wherein the defoaming agent is a weak acid salt, is unstable and increases the storage time of the solution with the increase of the H in the solution+The concentration increases, the pH decreases and the additive function diminishes until it is spent.
2. The method for detecting the quality of the silicon wafer alkali polishing additive as claimed in claim 1, wherein the alkali polishing additive further comprises a buffering agent and a high-efficiency accelerator.
3. The method for detecting the quality of the silicon wafer alkali polishing additive as claimed in claim 2, wherein the buffering agent is sodium sulfate, and the high-efficiency accelerator is a nonylphenol anionic surfactant.
4. The method for detecting the quality of the silicon wafer alkali polishing additive as claimed in claim 1, wherein the pH value of the alkali polishing additive is accurately measured by a pH meter.
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| CN101451045A (en) * | 2007-12-07 | 2009-06-10 | 安集微电子（上海）有限公司 | Process for preparing chemico-mechanical polishing liquid |
| CN101451046A (en) * | 2008-12-30 | 2009-06-10 | 清华大学 | Polishing composite for silicon wafer polishing |
| CN107004594A (en) * | 2014-12-15 | 2017-08-01 | 信越半导体株式会社 | The Ginding process of Silicon Wafer |
| CN108789163A (en) * | 2018-05-30 | 2018-11-13 | 郑州合晶硅材料有限公司 | A kind of silicon chip back side polishing device and polishing method |
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| CN101451045A (en) * | 2007-12-07 | 2009-06-10 | 安集微电子（上海）有限公司 | Process for preparing chemico-mechanical polishing liquid |
| CN101451046A (en) * | 2008-12-30 | 2009-06-10 | 清华大学 | Polishing composite for silicon wafer polishing |
| CN107004594A (en) * | 2014-12-15 | 2017-08-01 | 信越半导体株式会社 | The Ginding process of Silicon Wafer |
| CN108789163A (en) * | 2018-05-30 | 2018-11-13 | 郑州合晶硅材料有限公司 | A kind of silicon chip back side polishing device and polishing method |
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