JPS5944646A - Method for evaluating purity of semiconductor sealing resin - Google Patents

Abstract

PURPOSE:To measure the purity of a sealing resin by irradiating X-rays, electron rays or gamma-rays to a semiconductor sealing resin material and detecting the intrinsic X-ray intensity generated by the chlorine atom in the material. CONSTITUTION:An element sealed with an epoxy resin for semiconductor sealing as a sample is polished of its surface with sand paper, whereafter the element is cleaned with ethyl alcohol. X-rays are irradiated to the surface thereof, and the intrinsic X-ray (ClKalpha ray) of chlorine of 4.73Angstrom wavelength in the generated X-rays is separated by a germanium single crystal. The intensity thereof is detected with a proportional counter and the content of chlorine is detected. The sample may be powder which is a raw material for molding or may be the material after formed into the element. The detection of the chlorine content up to 10ppm with the sample of about 30mm. diameter produced by pressure molding of resin powder and up to 50ppm with the same of about 5mm. width sealed therein with a semiconductor is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method for evaluating the purity of semiconductor encapsulation resin.

[Technical Background of the Invention and its Problems] The encapsulating materials most commonly used for semiconductor encapsulation at present are synthetic resins such as epoxy resins and silicone resins.

It is known that the purity of these encapsulating resin materials is one of the main factors that determines the lifespan of the encapsulated semiconductor element. That is, impurities such as NaCl contained in the resin are ionized by coexistence with water and become a direct cause of corrosion of the aluminum wiring on the surface of the semiconductor element.

In addition, these ionic impurities also contribute to the deterioration of the electrical characteristics of semiconductors.

Table 1 shows the relationship between the impurity content contained in the sealing resin material and whether the element is good or defective.As is clear from the table, the impurity level 1 and the resin material There is a clear correlation between the occurrence of defective products in devices manufactured using this method.

Table 1 (Unit: Pi'm) Therefore, in the development and manufacture of resin materials for semiconductor encapsulation, the reduction of impurity components that are easily ionized, their evaluation, and tube W technology are critical issues.

-4, selection of crystal quality sealing resin material 1 item η according to strain 1
Purity evaluation methods for control are becoming extremely expensive.

As a conventional method for evaluating fat impurities, a method is known in which the sealing fat is destroyed, turned into a solution, and the impurity components are removed.
] However, this method is very complicated because the sealing resin is a composite material made of various components, and the accuracy is insufficient. Another known method is to extract impurities with water under heated or pressurized conditions, and then extract various ions from the extracted water using atomic absorption spectrometry or spectrophotometry. (Nikkei Electronics.

1978, 11.27. )', 145-161)
This method evaluates the sealing resin particles by extracting and separating a large number of impurities and evaporating them.However, extraction and quantitative determination of a large number of impurities is cumbersome and time-consuming. It wasn't on point.

Against this background, there has been a desire for a method that can quickly, efficiently, and highly accurately evaluate the purity of the encapsulating resin after semiconductor encapsulation or the encapsulating resin material powder before encapsulation.

[Purpose of the Invention] The present invention was made to improve the shortcomings of the prior art in the purity rF value method of resin materials for resisting live conductors, and provides a highly accurate and simple evaluation method '5. ! : The purpose is to provide -4.

[Summary of the Invention] The method for evaluating the purity of a semiconductor inhibiting resin of the present invention involves irradiating a resin material with radiation such as X-rays, electron beams, or γ-rays (2. The method is characterized in that the purity of the sealing resin is measured based on the detected intensity.

That is, when a resin is irradiated with radiation, X-rays are generated having wavelength components caused by the components constituting the resin. In the present invention, from among such X decoys, the same wavelength component IJII-5 elements caused by chlorine atoms is separated and detected,
Measure its strength and use it as an index of impurity content. It evaluates the purity of

The present invention will be explained in more detail below.

d. (The sealing resin used as the raw material may be in powder form as a molding raw material or in the form of a molded raw material after the element has been formed. When measuring molding raw material powder, the raw material powder itself or further crushed powder may be used.) 7 is placed in a liquid test container with a thin film of polyester or polypropylene stretched on the bottom for measurement. In addition, to measure the resin after sealing, the element itself may be measured in step 1. However, the surface may be washed with a solvent or rubbed with sandpaper, or the surface may be sandpapered with sandpaper. Grinding provides even more reproducible results.

This sample is irradiated with radiation such as X-rays, electron beams, and γ-rays to generate the inherent Xi of the component elements. Separate the characteristic X-rays caused by
The impurity content can be evaluated by measuring back the frequency and comparing the obtained measured value with a preset reference value.

The reason why chlorine was adopted as a pure IW indicator in the present invention is based on the following opinion.

That is, as is clear from Table J above, the tendency of the extracted impurity content is almost the same regardless of the impurity component, and the amount of chlorine is the largest. Chlorine is generally known to be one of the 9 causes of metal layer corrosion, and high concentrations are often detected in the decimal part of semiconductor AI wiring accidents.

From the knowledge of Kowa et al., it has become clear that it is most appropriate to use chlorine as the purity indicator for current semiconductor inhibiting resins1.
, and the results of various experimental runs, - Examples and [2
As shown in Figure 1, there is a difference between extracted chlorine and extracted chlorine. Therefore, the correlation between the occurrence of semiconductor defects and the amount of extracted chlorine can be replaced with the total amount of chlorine, and it is extremely effective to use the total cumulative amount of salt as a purity index. That is, the purity value of the inhibitor resin can be determined by the chlorine-specific X-ray intensity int+, which corresponds to the total chlorine fish.

[Efficacy of invention:! k ] Restraint resins near l/Tφ have been improved and have a considerably low impurity level, but according to the method of the present invention, resin powder is added and molded, and a sample with a diameter of about 30 mm has a concentration of 10 ppm. −
4, 5 ml of semiconductor-sealed liJ! Any of these can detect and quantify chlorine amounts up to 50 pprn, so even high purity resins near Rj' can be quickly evaluated. In addition, as samples to be evaluated, the raw material powder and the element f'1 after molding were used. Mo*fi 4'-
It can be analyzed non-destructively using a method of
, [Example of the Invention] Elements sealed with seven types of commercially available epoxy resins for semiconductor blocking were mixed with a sample, and the surface thereof was ground with sandpaper and then washed with ethyl alcohol.

Next, the surface is irradiated with KX-rays 7, and generation 1. Of the X-rays, the wavelength is 4.73, and the unique X-rays of chlorine (CIKα rays)
4 to 1 was separated using a germanium single crystal, and its intensity was detected using a number function, and the chlorine and zombination were calculated. For comparison, the amount of impurities in the same sample was measured using an impurity amount measurement method using water extraction. The measurement using the method of the present invention required approximately 10 public expenditures, while the comparative method required approximately 3 hours.

The results of the examples of the present invention are shown in Table 2.

The same table also shows the results of a pressure puller bias test, which is an accelerated test method for semiconductor device life.

As shown in the table, according to the method of the present invention, it is possible to detect the impurity concentration of the sealing resin extremely accurately and in a short time, and the results are highly correlated with the element life. It has become clear that this method is an excellent method for evaluating sealing resins.

Eye, Dinghai 9 2nd table ※ Time to cumulative defective rate 50% (median 1if
e)

[Brief explanation of drawings]

Representative Patent Attorney Noriyuki Chika (1 person) Figure 1

Claims (1)

[Claims] Semiconductor encapsulation resin is irradiated with radiation and unique X-rays, which are generated more frequently than chlorine atoms in semiconductor encapsulation resin, are detected.