JPS62247519A - Treatment of semiconductor substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the formation of defects, particularly in semiconductor substrates. oval) defects (de
The present invention relates to a method for processing a conductor substrate to minimize the formation of RACH, and a conductor substrate processed by the method. In particular, the present invention provides an elliptical defect 11
<In order to minimize the formation of molecules, the substrate is cleaned with chemicals, and molecular beam eclipse (Ml (IC)
A thin oxide layer is provided as a protector against contamination occurring during the +FF process of growing a semiconductor structure having a heterogeneous structure (hcterostrucLcre) on the substrate by the ular beam IpiLaxy method. The present invention relates to a method for processing a conductor substrate and a semiconductor substrate processed by the method.

DESCRIPTION OF THE PRIOR ART The 1-method is described in U.S. Pat. No. 3,969,164. Elsewhere, November 1980.

0, Brehardt, Sbringa Press, Berlin;
Heidelberg (II, C, I'rt!yl+ar
dL, Springar I'ress, 1ler
Lin,! Volume 3, No. 7, edited by Lcidelberg)
On page 3, there is a paper by Dr. Ploog (-Crystals: Growth, Properties and Applications).
wth.

Properties and Applications
ns) and 1983 thin solid film (Th1n 5lid
Films) Volume 100, Page 291 [Molecular-
Line shrimp taxi (Molecular (camEpiL)
This can be found in the paper by Mr. Δ, Y. Cho entitled III-V group μ conductor growth and its characteristics 1 by Δ, Y.

The above method is particularly suitable for selectively doped n-Δ1xG
a+-xΔs/GaAs (x is a predetermined number) 5 (Related to molecular beam epitaxy growth of ridge structure. The method described in 1- is not limited to these structures and can also be used for other semiconductor substrates.ii
It turned out to be J-Noh.

A l x Ga + - EΔS further grown by GaAs and molecular beam epitaxy (M n E )
A contamination-free GaAs surface is important in determining the quality of the layer. Substrate wafers are typically cleaned with solutions of various chemicals. A thin oxide layer then prevents GaΔS (gallium arsenide) from contaminating during the next wafer processing! l
- made to do. The most widely used method of processing GaAs substrates is TI, SO4/II = o t
/ II , 0 mixed solution J, (This is a chemical etching method. II > SO4 / If , O, / 1
120 mixture is surface stabilized (passivaLior,
) This is thought to be due to the creation of a thin surface oxidation layer.

This oxide layer can be removed by heating before performing the 1-M+3 IC growth. It also protects the etched surface from contamination by particles during substrate processing after the etching process. However, recently HFS O4/II in water
Yo? /11.0''-Zinging and rinsing treatments have been found not to produce any surface-stabilizing oxide film on GaΔS surfaces with Miller index (+00).

Instead, surface oxides are only produced by samples treated in air after etching.

In particular, molybdenum (Mo) sample holder 1
．． (in) Produced during heating for half-1 attachment.

Specifically, the conventional method involves multiple degreasing by sequentially rinsing the substrate in trichlorethylene, acetone, and water.

Thereafter, the substrate is boiled in hydrochloric acid. and 48 for 1 minute
H p S 0 with concentration ratio (3:l:I) at °C
4/II, 0, /1 (.

Perform free etching with a stagnant solution of 0. .

(Note that the concentration, temperature, and time IJm listed in 1. are representative examples, and other values may actually be used.) In order to stop the etching effect (cLchanL), the wafer-shaped substrate is immersed in water and filtered. Blow dry with NtC (nitrogen) gas.

(Problems with the Prior Art) As is clear from the above, the conventional method involves a number of separate steps and requires the use of boiling hydrochloric acid and a high temperature etching solution. Yes, it becomes very complicated. This multiple process means that substrate processing requires a relatively long period of time.

Therefore, the object of the present invention is to easily, quickly, and reliably form a layer on a substrate. It is desirable to minimize the formation of elliptical defects during the growth of the conductor structure. It is further an object of the present invention to expose the substrate 1 to air for a period of, for example, at least 62, 3 weeks before growing a semiconductor structure on the substrate 1 without losing its properties that reduce the formation of defects. An object of the present invention is to provide a method for processing semiconductor substrates that can be stored.

(Means and operations for solving the gap) In order to achieve the object 1-1, the method for processing a semiconductor substrate according to the present invention comprises: (a) wearing-free fibers soaked in an oxidative etching solution; Etch polishing the substrate using a paper abrasive wrap L, (b)
'', the substrate is placed in e-sulfuric acid in a stirred state for treatment.

The present invention provides an oval defect (de[ect
) to minimize the formation of heterogeneous structures ( heLcyosLrucL
zl l-' 7 it': tlb
r. -3J-d- 7. A'- Mu jk J
- r -r NOA IV li-4 1y Applicable to a semiconductor substrate processing method.

The oxidative etching solution contains activated chlorine (chlorine) at a concentration of 0.5 to 6.5%, preferably 2.0%.
) is (f)Na0C! (sodium hypochlorite).

The above substrate is GaAs (gallium arsenide) and the strong acid is H,
So, (sulfuric acid). The concentration of concentrated sulfuric acid (pso*) is preferably 98%.

J-Mechanical and Chemical edge polishing is performed at room temperature.

Furthermore, since the treatment in concentrated acid is carried out at room temperature, the dangers associated with conventional complicated thermal treatments can be avoided.

- The substrates are placed sequentially in two separate baths of concentrated acid and subjected to ultrasonic agitation in both baths. In this case, the duration of treatment with concentrated acid is between 5 and 10 minutes for each bath.

The polishing wrap is manufactured by Polytcx and is designated as supre+*a I.
Lens paper of the type sold under 241142 is good.

” The bipedal substrate is preheated in air in a dust-free condition before being mounted on the substrate holder.

1. Machine: Cut (sa) before chemical edging polishing.
w cut) L, first polish with diamond paste to remove scratches.

The treatment with concentrated acid should be waited for about 5 minutes or longer.

The semiconductor substrate may be a substrate other than GaAs (gallium arsenide), for example, indium phosphide.

1- The oxidative etching solution may be other than Name I, such as methanol bromide (bromium mcLbanol).
But that's fine.

1. As shown as a feature of the invention of footwood, the number of L is smaller than that of the conventional method. All treatments are carried out at room temperature.
IC practice requires relatively simple chemistry and equipment, and is time-constrained. Fourth, the effect of the new semiconductor substrate processing method of the present invention is that the processed high-mobility -1-dimensional electron gas (2
1) selectively doped n exhibiting
It is represented by 74 structures of -Δ1XGa+-xAs/GaΔS. Specifically, when illuminating (1llu*jnaLion) using +8nm undoped AlXGa, -, Δs/GaAs spacer, 108am'/
Mobility exceeding Vs has been obtained.

These values are the highest reported to date for this narrow spacer. Further, according to the substrate processing method according to the present invention, the density of defects was dramatically reduced to 200 cm-'' or less.

(Description of Examples) Hereinafter, two embodiments of the semiconductor substrate processing method according to the present invention will be described with reference to the drawings.

FIG. 1 shows the surface of a semiconductor substrate after being treated with II, SO, (sulfuric acid).

FIG. 2 shows two samples, one deposited on a substrate treated according to the conventional method (sample 1) and the other on a substrate treated according to the method according to the invention (sample 2). Heterogeneous structure (haLcr
11all (hole) mobility as a function of temperature obtained from o 5 structures).

In the following examples, gallium arsenide (gallium arsenide)
Ilarscnida) substrate doped with Si (silicon) n-ΔI x Ga +, aA s/G
aΔS heterogeneous km Hiroshi's original desk] 11 ['to the river N1・tl
One sound is made for B6.

Selectively doped with Si (silicon), n-Δ1
The heterogeneous structure of xGa+, xΔS is expressed as plants = (7, (qLla
si horizontal) evaporation resin type M
It was grown in an I(E apparatus. This deep horizontal evaporation type M r(l') apparatus continuously rotates J, (
Surround the plate holder and the entire growth area with liquid nitrogen (1,
N,) cooling shroud. For the heterogeneous structure, the growth rate of GaAs is l 1tta
/ hr and the growth temperature is as low as 600°C.
0) was deposited on an undoped semi-insulating 18S substrate. Identical 2-inch diameter liquid capsules (L Li'j C: 1quid) after the treatments described below.
P, ncapsulation Czochralsk
M due to simultaneous deposition of two substrate pieces split from the GaAs wafer grown by y).

(molybdenum) soldered to the sample holder.

Uncleaved wafers are first treated with diamond paste to create saw-like scratches (
saw-cut damage) and then Na0
Etch polishing (wrapping) was performed by contacting the lens with non-abrasive lens paper soaked in C1 (sulfur/lium hypochlorite) solution. The result was a mirror-like (l''-).

-1- One half of the Eva was etched using the following conventional method. Slice first in trichlorethylene,
Final degreasing was performed by successive rinsing in acetone and water. After boiling in hydrochloric acid, the substrates were incubated for 1 min at 48°C (3
:l:I) II v S O4/II p Oy /
Free etching was performed with a stagnant solution of II y O. Add +h of etching agent (enchant)
The wafer was soaked in water and filtered.
It was blown dry with (nitrogen) gas.

! -The other part of the GaΔS wafer that is not marked is
It was placed twice in concentrated sulfuric acid maintained at 300 K and stirred with ultrasonic waves. The wafer was rinsed in double water and blown dry with NTC (Nitrogen) once again. Both parts of the original wafer were placed in a molybdenum sample holder heated (250 °C) in liquid indium on a clean bench in a clean room under dust-free conditions.
．． It was planted. Immediately after that, load the sample [J
I took it to Wakushi Station 11.

For sample 2, the substrate was initially heated to 250°C to 300°C.
Heat up to 1.11° for 3 minutes in dust-free conditions before attaching.
'ru. In the present invention, this heating performed by P is In
"It's important": Moderately. , 11. So, the two processing durations in the middle are not a problem (the time for one processing) is usually 5
10 minutes.

Even if the treatment time is long, it will not be much of a problem as long as you make sure that the temperature of the sulfuric acid bath is between 4° and room temperature. The temperature increase is because this bath is stirred by ultrasonic waves!・I need to be careful. Treatment with two successive acid baths is preferably used so that contamination remains in the first bath.

J-Number of minutes with half-ell (Soldering) -
Miller index between J' and rA (100) 0)G a
It has been found that oxides are generated on the As substrate 1-, protecting the surface from carbon particle contamination. M assie
(?Tsushii) and Contour revealed this fact. Their achievements are [applied physics (^ppl
ied ['hysics) journal! No. 588, page 806 (published in 1985). M1
3 After being transported to the E-growth chamber, the oxide on the surface is heat absorbed by heating the wafer from 530°C to 560°C in a flux of A S 4 (arsenic).

After the desorption process is completed, a clean (2x4) surface reconstruction is observed in the reflection high-energy electron diffraction (+? II EE D ) pattern.

As for the order of the layers of the heterostructure, the residual doping concentration is 10
“c+a-”(f) undoped 2μm
undoped A I 0.33G ao,ayΔS spacer 53n with a thickness of p-GaAs buffer layer 18n-
Si-doped A with a thickness of m! a3+G a
It includes an O,L17 AS layer and an undoped 8 nm thick GaAs cab layer. After growth, the 1-side layer was examined with a phase-symmetric microscope.

The Hall effect measurement was performed on a rectangular sample divided in the temperature range expressed by 4K<T<300.
+1. Jt k total iJ: / ,
,・,r・・,,~N?・Mu1yo ・Puri2 ↓, it was. The sample was placed in an automatic cooler (cryosLaL) in which 1ie (helium) was continuously flowing, and measurements were performed under computer control.

FIG. 1 shows a microphotograph of a representative area of a wafer treated with sulfuric acid (11,SO,) only. From this, no oval defect is clearly visible. This defect is caused by "crystal growth (Cr1stal Gr.

wth) J magazine (published in 1981), Volume 51, Page 299, C, E, C, food (food), Ia
.

RoLhbun, ■■, Ohno
), D a.

Simon (Sia+ona)'s -) paper and applied physics'', the 23rd edition of the 11th language magazine (published in 19B/I).
Volume 164, Y, Suzuki (picture book), M, Seki, Y.

It is described in the JT paper by Horikoshi and [1, Saiki Moto. Almost 11 layer-substrate (epliiaycr
The total density of elliptical defects occurring at the -substraLc) interface is lower than 200 cta-'' for a 2μ-thick heterostructure grown on the processed J, (plate) with the method according to the invention. According to this result, it is possible to obtain an L-side layer with almost no defects by processing the surface of the GaAs (IT!I) plate, which has been carried out in a very special manner, according to the present invention.
4/ II *In order for the elliptical defect density of the sample chemically etched with the O mixed solution to be as low as that according to the present invention, indium (In) should be added to the substrate surface during the process. This can only be achieved if the generation of the oxides is carried out under extremely dust-free conditions.

When the GaAs substrate according to the present invention is treated with sulfuric acid, contamination by carbon particles r on the surface hardly becomes a problem.

The advantage of processing GaAs substrates using IT, So, is that selectively doped n-A I
u, :+aG a 11. Ill? A S / G a
The A s heterogeneous structure can be demonstrated by Hall effect measurements.

In Figure 2, the Hall mobilities are If, So, /II
to p/ II, 0 etched slices (
Samples 1) and 11. So, processed with (sample 2
) as a function of temperature obtained from two heterogeneous structures deposited on a substrate slice. Surface treated with H,SO4 (sample 2), ■Hole mobility for the − grown heterostructure is 300 n, 4. A X l O”cm Goose 21)!・
; G channel 1" μ 7.3XIO'cm"/
3. When the temperature of the sample decreases, the mobility increases and 6.
2 1) ICG channel n *”4, 3 X IO”cm” measured after minaLion)
Then It=0.59xl O'co+'/Vs(-IL
become. These mobility values are based on a spacer as narrow as 18 nm (f, selectively doped, 11'Δl
xG a+−mA s/ G a△slJ′! This is the highest species structure ever reported.

Samples with similar mobility values and carrier densities! However, the data was within 10% of that of sample 2. Sample l is conventional II PS 04/H20P/II
It is grown on a Jk plate J- etched at 20. , this slight difference is due to the uncertainty of the applied measurement method.

(Effect of the invention) A GaAs substrate for growth by M r (E method) is
Indium (In) soldering in N to 0C1 (sodium hypochlorite) solution facilitates the generation of surface oxides for medium contamination protection. As a result, contamination by carbon particles can be avoided. The density of elliptical defects below 200 ctm-” is Ht
This is typically achieved for a 2 μm thick heterostructure grown on a substrate treated with SO4.

The advantages of the substrate processing method according to the invention are demonstrated by selectively doped n-Δ1xGax, +As/Ga8S heterostructure, high mobility 2D LCG.

If a spacer as narrow as 18r+n+ is used, a mobility exceeding IO"cm'/Vs can be obtained at 6 under illumination.

1-1 The semiconductor processing method according to the present invention is simple and simple.
The formation of defective portions during the growth of conductor structures can be dramatically reduced. Furthermore, it is possible to store it in a state where it is exposed to air while having the property of dramatically reducing the number of defects.

[Brief explanation of drawings]

FIG. 1 shows a microphotograph of the surface of a semiconductor substrate after it, so, treatment. Figure 2 shows two heterogeneous structures, one deposited on a substrate treated with the conventional method (Sample I) and the other on a substrate treated with the present invention (Sample 2). Figure 3 shows a characteristic graph of hole mobility as a function of temperature obtained from a heterogeneous structure. Engraving of side A (no change in content) Figure 1 was added to 11- M (K) Figure 2 procedural n was added (method) April 30, 1985

Claims (1)

[Claims] (1) In order to minimize the formation of oval defects, the semiconductor structure described above is a heterostructure, which is performed by cleaning the substrate with chemicals and using the molecular beam epitaxy (MBE) method. A method of processing a semiconductor substrate comprising an oxide layer as a protector against contamination generated during processing prior to growth on the substrate, the method comprising: (a) abrasion-free fibers immersed in an oxidative etching solution; Mechano-chemical etch polishing of the substrate using paper polishing wrap
tchpolishing); and (b) placing the substrate in a stirred concentrated sulfuric acid for treatment.