JPH031553A - Measuring method and apparatus for semiconductor - Google Patents

Abstract

PURPOSE:To measure a photoluminescent light emitted from a semiconductor sample and measure the distribution of defects along the depth direction of the semiconductor sample by a method wherein the semiconductor sample is dipped into solution obtained by adding hydrochloric acid to organic solvent to etch the semiconductor sample surface and, at the same time, an exciting light is applied to the semiconductor sample. CONSTITUTION:A sample holder 12 can be taken out of a chamber 11 and, after a sample 14 is attached to the holder 12, the holder 11 is housed in the chamber 11. The chamber 11 is filled with a suitable quantity of solution 13 and the sample 14 is dipped into the solution 13. That is, the sample surface is brought into contact with the solution and the etching of the sample surface is progressed. A light from a light source 15 is intermittently applied to the sample 14 in the solution 13 with a certain interval given by a chopper 16. Carriers in the surface of the sample 14 are excited by the application of the light and, by the recombination of the excited carries, a light is emitted. The emitted light is condensed by a condenser lens 17 and the condensed light is divided by a spectroscope and the photoluminescence is measured. With this constitution, the distribution of defects along the depth direction can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photoluminescence measurement method for investigating the properties of semiconductor samples, particularly compound semiconductor samples.

[Prior Art] In general, photoluminescence measurements are widely performed to investigate the properties of semiconductors. This measurement involves irradiating the surface of a semiconductor with excitation light to observe the light emitted when excited carriers inside the semiconductor near the surface recombine.

The intensity of photoluminescence is also related to defects near the semiconductor surface, and has a property that the intensity decreases as the number of defects increases.

By measuring the photoluminescence intensity using this change in photoluminescence intensity, the density of defects near the semiconductor surface is determined qualitatively or semi-quantitatively. For example, the surface of a GaAs wafer is CC
Ω2F2 or active ion etching (RI)
By measuring the photoluminescence intensity on the surface when etched in E) and comparing it with the photoluminescence intensity before etching by RIE, it is possible to obtain knowledge about the extent to which defects have been introduced by RIE.

Furthermore, the depth of defects introduced into the semiconductor by etching such as RIE is such that the GaAs surface etched by RIE is
It can be measured by repeating the operation of etching a small amount in a liquid such as 0 and measuring photoluminescence.

This method is described in the academic journal AI)I)11ed, for example.
0ptlcs 1978, Vol. 17, page 2556, M.
Kavabe.

N., Kanzaki, M., Masuda, and S.
It is described in Namba.

[Problem to be solved by the invention] However, in this way, etching of the semiconductor surface and
The operation of repeatedly measuring photoluminescence requires a great deal of effort, and the measurement point may shift each time the photoluminescence is measured.

An object of the present invention is to provide a method for measuring the depth distribution of defects in a semiconductor, in which photoluminescence is measured while etching the surface of the semiconductor.

A further object of the present invention is to provide a semiconductor defect depth distribution measuring device capable of measuring photoluminescence while etching the surface of a semiconductor and at the same time measuring the etching depth.

[Means for Solving the Problems] The present invention involves immersing a semiconductor sample in a solution prepared by adding hydrochloric acid as a solute to an organic solvent, etching the surface of the semiconductor sample with the solution, and applying excitation to the semiconductor sample. The method is characterized in that photoluminescence light emitted from the semiconductor sample is measured by irradiating the semiconductor sample with light, and the defect distribution in the depth direction of the semiconductor sample is measured from the photoluminescence light.

[Operation] When the surface of a semiconductor sample is brought into contact with a solution prepared by adding hydrochloric acid as a solute to an organic solvent consisting of at least one of methyl alcohol, ethylene trichloride, and ethane trichloride, the surface of the sample is etched. If photoluminescence is measured while the sample is immersed in a solution, photoluminescence in the depth direction will be obtained over time.

[Example code] The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the principle of the present invention.

Referring to FIG. 1, a holder 12 holds a semiconductor sample (hereinafter simply referred to as sample) 14 made of a chemical-resistant material such as Teflon in a container 11 made of a light-transmitting material such as quartz. , and a solution 13 for etching a sample, an etching apparatus is constituted.

The sample holder 12 can be taken out from the inside of the container 11, and is housed in the container 11 after the sample 14 is attached thereto. A solution 13 is placed in a suitable groove in the container 11, and the sample 1
4 is immersed in the solution. That is, the solution and the surface of the sample come into contact.

The surface of the sample that comes into contact with the solution is etched.

As in the prior art, the sample 14 in the solution 13 is irradiated with light from the light source 15 intermittently at regular intervals by the chopper 16 . Carriers on the surface of the sample 14 are excited by the light irradiation, and light is emitted by recombination of the excited carriers. The emitted light is converged by a condensing lens 17, and the converged light is separated into spectra by a spectrometer (not shown) to measure photoluminescence.

The solution 13 in the container 11 is a solvent containing at least one liquid selected from methyl alcohol, ethylene trichloride, and ethane trichloride to which hydrochloric acid is added as a solute. In particular, it is preferable to use a mixture of the above three types of liquids as the solvent, or to use only one type of liquid among the three types of liquids as the solvent. Also, the concentration of hydrochloric acid in the solvent is 10
It is desirable that vo be 1% or less.

Examples will be described in detail below.

■ Example 1 GaAs was used for sample 14, and 0.1vo1% was used for solution 13.
An experiment was conducted using a methanol solution of HCN. light source 1
5, a He-Ne laser was used and the wavelength was 632.8 nm.
, an output of 6 mW, a beam diameter of 200 μl, and a chopping frequency of 700 Hz.

The photoluminescence intensity of GaAs is at a wavelength of 865 r
Since it has a peak at +m, the wavelength is 865
Temporal changes in nm synchrotron radiation were measured.

On the other hand, as shown in FIG.
If IJ is set (see FIG. 3), the temporal change in photoluminescence intensity can be replaced by a change in the depth direction of the sample 14. Alternatively, the etching depth of the sample 14 after photoluminescence measurement can be measured assuming that the etching rate is linearly proportional to time, and the change in the depth direction can be approximated.

In this way, a graph of the relationship between etching depth and photoluminescence as shown in FIG. 2 can be obtained.

Example 2 The photoluminescence measuring device shown in FIG. 4 is a device for measuring temporal changes in photoluminescence spectra.

Using this device, it is possible to observe not only changes in the photoluminescence intensity of a specific wavelength, but also temporal changes in the spectrum.

Light from a light source 15 is chopped by a chopper 16 and split into two lights by a partially reflecting mirror 18. One of the two divided lights is irradiated onto the surface of the sample 14, and the other is converted into an electrical signal by the photoelectric converter 19,
It is manually powered by the lock-in amplifier 20.

Photoluminescence is emitted from the surface of the sample 14 excited by the excitation light. The emitted light passes through the condensing lens 17
The light is focused and enters the spectrometer 21. The spectrometer 21 obtains the spectrum of light, and the multichannel analyzer 22 converts it into an electrical signal.

The converted electric signal is given to the lock-in amplifier 20 together with the electric signal from the photoelectric converter 19, and the lock-in amplifier 20 converts the phase of the converted electric signal to the charging converter 1.
The electrical signal from 9 is adjusted as a reference and output to the recorder 23.

In the case of this apparatus as well, the distribution of defects in the depth direction can be known by determining the relationship between the etching depth and time of the sample in advance in the same manner as in Example 1.

Example 3 The photoluminescence measuring device shown in FIG. 5 is a device that simultaneously measures the relationship between etching depth and photoluminescence intensity.

Light from the light source 15 is irradiated onto the sample 14 by a half mirror 25 of the interferometer 24 and a mirror 26 installed in front of the condensing lens 17. Further, the reflected light from the sample 14 is guided to the interferometer 24 by a mirror 26. Interferometer 24
A converter 27 converts the change in the interference between the excitation light and the reflected light into an electrical signal representing the etching depth.

The photoluminescence is separated by a spectrometer 21 through an optical filter 28, and an S-1 type photomultiplier tube 29 converts the intensity of light at a specific frequency into an electrical signal. The phase of this electrical signal is adjusted by the lock-in amplifier 20 and input to the synthesizer 30.

The etching depth measurement and the photoluminescence measurement are performed simultaneously, and in the synthesizer 30, the signals from the converter 27 and the lock-in amplifier 20 are recorded by the recorder 23 in correspondence with the X-axis and the Y-axis, respectively. In this way, a graph representing the relationship between etching depth and photoluminescence is obtained.

An Ar laser with a wavelength of 514.5 nm was used as the light source of the photoluminescence measuring device shown in Fig. 5, and with a chopping frequency of 700 Hz, 0.1 vol. The photoluminescence of the GaAs sample was measured.

As a result, a graph showing the relationship between etching depth and photoluminescence was obtained.

According to this embodiment, it is possible to save the effort of determining the relationship between time and etching depth in advance.

Example 4 The photoluminescence measuring device shown in FIG. 6 is also a device for directly measuring the relationship between etching depth and photoluminescence intensity, similar to the measuring device shown in FIG. 4.

Measurement of photoluminescence is carried out in the same manner as the measuring device shown in FIG.

The etching depth is measured by using an electrode 31 provided in the solution 13.
A voltage is applied between the sample 14 and the sample 14 by a power source 32, and the etching depth is determined from the change in the current flowing there. That is, the current increases as the sample is etched and the concentration of ions in the solution increases. This increase in current is converted into etching depth.

Thereafter, similarly to Example 3, the determined photoluminescence intensity and etching depth are combined by the synthesizer 29 and recorded by the recorder 23.

Note that the present invention is not limited to GaAs as a sample for measuring photoluminescence, and can be applied to various materials based on the gist of the present invention. The gist of the present invention is to provide a method for measuring photoluminescence in which the surface of a material is removed minute by minute and photoluminescence is measured at the same time. From this, A, Q GaAs,
I nGaAs, GaAsP, AN GaP, A
l11 nP.

It can also be applied to ternary mixed crystal semiconductors such as InAj7As and GaInP, and quaternary mixed crystal semiconductors such as InGaAsP, InA, and 17AsP. It goes without saying that Aj7As, A, QP, etc. other than GaAs can be widely applied as binary compound semiconductors.

[Effect of the invention] According to the present invention, methyl alcohol, ethylene trichloride,
A solution obtained by adding hydrochloric acid as a solute to a solvent containing at least one type of liquid of trichlorethane is brought into contact with the surface of a compound semiconductor sample, and excitation light is applied to the sample through the solution to measure photoluminescence. , the depth distribution of defects in a sample can be easily measured.

Further, according to the present invention, by providing the etching means, the photoluminescence measuring means, and the etching depth measuring means, it is possible to simultaneously measure the etching depth while measuring the photoluminescence.

Sense measuring device, respectively, according to Example 2. Example 3
．． FIG. 4 is a schematic diagram showing Example 4.

DESCRIPTION OF SYMBOLS 11... Container, 12... Sample holder, 13... Solution.

14... Sample, 15... Light source, 16... Chopper 17... Condensing lens, 18... Partial reflection mirror
19... Photoelectric converter, 20... Lock-in amplifier,
21... Spectrometer, 22... Multi-channel analyzer, 23... Recorder, 24... Interferometer, 25... Half mirror-26... Mirror 27
Converter, 28 Optical filter 29 Photomultiplier, 3o Combiner, 31 Electrode, 32
··power supply.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of an etching apparatus used in the semiconductor measurement method of the present invention, Figure 2 is a graph showing the relationship between etching depth and photoluminescence intensity, and Figure 3 is a graph showing the relationship between excitation light power and etching rate. Graphs, Figures 4 to 6 are photoluminescent Figure 2

Claims (1)

[Claims] 1. A semiconductor sample is immersed in a solution containing an organic solvent and hydrochloric acid as a solute, the surface of the semiconductor sample is etched by the solution, and the semiconductor sample is irradiated with excitation light. A method for measuring a semiconductor, comprising: measuring photoluminescence light emitted from the semiconductor sample; and measuring defect distribution in the depth direction of the semiconductor sample from the photoluminescence light. 2. The semiconductor measuring method according to claim 1, wherein when measuring the defect distribution, the etching depth of the semiconductor sample is also measured. 3. An etching device that etches the semiconductor sample in the container while holding the semiconductor sample in a container that transmits light; and irradiating the semiconductor sample held in the etching device with excitation light from outside the container. and an etching depth measuring means for measuring the etching depth of the semiconductor sample. A semiconductor measuring device used in the semiconductor measuring method according to claim 1.