JPS62277736A - Heat treatment method for compound semiconductor - Google Patents

Abstract

PURPOSE:To prevent the permeation of a constituent element having high vapor pressure as a compound semiconductor, and to inhibit the dissociation of the element by thermally treating a metallic silicide film containing nitrogen as a heat treatment protective film. CONSTITUTION:An ion implantation layer 12 is formed selectively into a GaAs substrate 11. A metallic silicide film 13 is used as a protective film at the time of activation heat treatment after ion implantation, a material, such as tungsten silicide, molybdenum-silicide, tungsten-molybdenum-silicide, etc. is employed, and the film 13 is shaped through the so-called reactive sputtering method, etc. in which nitrogen gas is caused to flow into a sputtering atmosphere in order to contain nitrogen. The content of nitrogen is 1-50%. Film thickness is approximately 0.01-1mum. The surface of the metallic silicide film 13 may also be coated with an insulating film 14, such as SiO2, SiO3N4, etc. Ga is not detected in the metallic silicide film 13 after heat treatment, thus inhibiting dissociation from the GaAs substrate 11 of As.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a heat treatment method using a heat treatment protective film used in the manufacturing process of compound semiconductor devices.

[Conventional technology]

GaAs, InP, GaP, InAs, InAtAsX
Common heat treatment methods for compound semiconductors such as InGaAtAs include sputtering, chemical vapor deposition (CVD), plasma-enhanced CVD, and other methods for depositing insulating films such as silicon oxide (SiOz) and silicon nitride (SisN4) films. There is a method in which a Yoshi compound is coated on the surface of a conductor layer and used as a heat treatment protective film. If, for example, GaAB is heat-treated at 800°C for 20 minutes using this method, Ca will be detected in the heat-treated protective film.
No. (1984) 527 pages (M, Kuzuhara
and H, Kohzu' SiOxNy cappe
d annealing for Si-1npla
nted GaAs”, J, Appl, P
h)'s.

Lett, vol. 44. no, 5 (1984) 52
7)).

As shown in FIG. 8, a sample in which S is N4 #2 and a 5ift film 3 were formed as an insulating film on a GaAa substrate 1 and heat-treated at 800°C for 20 minutes was subjected to secondary ion mass spectrometry (5 secondary ion mass spectrometry). M
ass 5pectroscopy: SIMS)
The results are shown in Figure 9. The spuck time on the horizontal axis corresponds to the depth from the film surface. In the ablated Li film, 10) of Ga was detected with a C count of approximately 0.5% relative to the substrate. On the other hand, As is below the detection limit (10 counts).

On the other hand, without using a heat-treated antiseptic film, for example, GaAs,
There is also a so-called capless annealing method in which As pressure is applied to InAa, etc., and P pressure is applied to InPlGaP, etc. (for example, Journal Φ Op Applied Physics Vol. 50 (1979) 54
1 page (J, Kaaahara, M, Arai
and N, WataHabe' Capless
Anneal of Ion Implanted
GaAs1n Controlled Ar5en
ic vapor', J.

APPI, Phys It vol-50 (197
9) 541), Applied Physics Letters Vol. 37, No. 1 (1980), p. 64 (G, A,
Antipas' Prevention of
Inp 5 surface decomposite
ion in 1quid phase epita
xial growth', Appl, Ph7a
, Lett, vol.

37, no. 1 (1980) 64) etc.).

The concept of capless annealing is that during heat treatment,
The purpose of this method is to bring elements such as As and P, which are thermally decomposed and have a high vapor pressure, into a thermal equilibrium state by applying the pressure of the As, P, etc. to the surface of the substrate.

[Problem that the invention seeks to solve]

In both of the above-mentioned technologies, when taking a GaA@substrate as an example, the behavior of its constituent elements As and Ga appears to be contradictory. That is, in the first technique, Ga escapes from the substrate and accumulates in the heat-treated retaining film (insulating film), but As is not detected in the insulating film.
In the conventional technology, AI is easily dissociated from the substrate.
Although pressure is applied, no particular measures are taken for Ga.

This means that heat treatment is protected! This can be explained without contradiction by considering that an insulating film, which is normally used as a single film, allows As to pass through. 29. Assuming that thermally decomposed As passes through the other F & films, and on the other hand, Ga and As are thermally decomposed almost equidistantly, when As escapes, Ga remains in the insulating film due to its low vapor pressure. This causes the particles to diffuse into the interior, resulting in residual precipitation.

For example, when an insulating film such as the one described above is used as a heat-treated lumbar membrane for heat treatment to activate the ion-implanted layer, if the compound semiconductor, for example, GaAs, thermally decomposes, the carrier concentration distribution of the implanted layer will change. expands abnormally, making it difficult to control the shape of the concentration distribution. Therefore, if a field effect transistor is formed using a compound semiconductor substrate heat-treated in this way, for example, the pinch-off voltage will increase, the mutual conductance will deteriorate, the standard deviation of the threshold voltage will increase, and the characteristics between wafers will change. This results in variations in

On the other hand, in the capless annealing method, All-? It is difficult to strictly control the vapor pressure of P, and dangerous gases such as arsine and phosphine must be handled.

[Means for solving problems]

The present invention provides heat treatment for a metal silicide film containing nitrogen.
The Ji film is subjected to heat treatment.

[Effect]

The metal silicide film containing nitrogen does not allow the constituent elements with high vapor pressure of the compound semiconductor to pass through during heat treatment, and suppresses their dissociation.

〔Example〕

(Example 1) 5I, l is a sectional view showing an embodiment of the present invention.

In the figure, 11 is a semi-insulating GaAs substrate as a compound semiconductor substrate. 12 is an ion implantation layer selectively formed in this GaAs substrate 11, for example, 5t1Se.
etc. ions were implanted at an acceleration voltage of 10 to 200 kev1 i10
It was formed by implantation under conditions of ~1015 ions/image. 13 is a nitrogen-containing metal silicide film used as a protective film during activation heat treatment after ion implantation, such as tungsten silicide, molybdenum silicide, mental silicide, niobium silicide, or tungsten molybdenum silicide. It was formed using the following materials. In order to contain Co-5, such a metal silicide film can be formed by, for example, sputtering using a metal silicide as a target as described above, or sputtering using a simultaneous target of the metal and silicon (so-called Co-5 putter). At this time, it is formed by a so-called reactive sputtering method or the like in which nitrogen gas is introduced into a snow ivy atmosphere. Nitrogen content is 1-50
%. Further, the film thickness may be 0.01 to 1 μm8.

Activation heat treatment of the ion-implanted layer may be performed in this state, but depending on the heat treatment atmosphere, the atmospheric gas may react with the metal silicide that acts as nitrogen. The surface of the silicide film 13 may be further coated with an insulating film 14 of 5iOz, Si, N4, or the like. A nitrogen-containing metal silicide film 13 and an insulating film 14 may also be deposited on the back surface of the GaAs substrate 11 as shown in the figure.

In this state, heat treatment is performed at a temperature of, for example, 750 to 1000° C. for about 1 second to 1 hour to activate the ion implantation layer 12.

Tungsten silicide (WSjN) containing nitrogen was used as the gold silicide film 13, and 8
FIG. 2 shows the results of SIMS analysis before and after heat treatment when heat treatment was performed at 00°C for 20 minutes. The figure (a) shows the analysis results before heat treatment, and the figure (b) shows the analysis results after heat treatment.

From the same figure, before and after heat treatment, Ga, As, W%5i2N
No change in each level is observed. In addition, unlike the case of FIG. 9 in which an insulating film is used as a heat treatment protective film, no Ca is detected in the metal silicide film 13 even after heat treatment. In other words, the diffusion of Ga into the protective film is
If this is due to the omission of As, the GaAs substrate 1 of As
Dissociation from 1 is suppressed. The fact that this explanation is correct will be explained in detail with regard to Example 2.

FIG. 3 shows the carrier concentration distribution in the depth direction after the ion-implanted layer 12 is heat-treated. In the figure, (a) shows the case of this embodiment, and (b) shows the case where an insulating film (Si3N4) is used as a heat treatment protective film. Ion implantation conditions, heat treatment conditions, etc. are all the same.

Comparing the two, it is clear that this example has a better carrier a.
The density distribution curve is steep, the concentration is high, and there is no tail, which means that the implanted ions have little diffusion and a high activation rate. This is because thermal dissociation of Ga and A8 was suppressed.

(Two examples FIG. 4 is a sectional view showing a second embodiment of the invention.

In this embodiment, for example, an insulating film 15 of 5iOz, Si3N4, etc. is sandwiched between a semi-converting GaAs substrate 11 and a metal silicide film 13 containing nitrogen, and the insulating film 15 of 5iOz, Si3N4, etc. This is an example in which the two-layer film No. 13 was used as a heat treatment protective film.

The insulating film 15 is formed by plasma-enhanced chemical vapor deposition (P-CVD).
) formed by S is N4 m (300A)
and 5i02 film (1200A) two-layer film (SixN+
A GaAs substrate 11 ) was used as the film, WS t N was used as the metal silicide film 13 , and the film was heated at 800°C at 20°C.
SI after heat treatment for the case of heat treatment for 1 minute
The MS analysis results are shown in FIG.

In the same figure, there is an As peak (indicated by A in the figure) at the interface between the metal silicide film 13 and the insulating film 15. It is a stopper, and furthermore, As is S.
Is it possible to pass through an insulation film such as i02.513N4?
Alternatively, it has been proven that the diffusion coefficient in the insulating film is extremely large.

Next, when looking at the level of Ga in the 1st film 15 in the same figure, it is about 1/10 or less compared to the case of FIG. 9. This is because the amount of separation from the GaAS substrate 11 was suppressed. 19. When only the insulating film is used as a heat-treated protective film (in the case of Fig. 9), Ga and As
Assuming that the same amounts of As and Ca are dissociated, As is permeated through the embryonic membrane 10 times more than in this example, and Ca
It is interpreted that the amount detected in the membrane will also increase by 10 times. In other words, the four heat-treated protective films consisting of an insulating film of 5t(h or 5tsN<, etc.) and a two-layer structure of WSiN in this example have an As
It can be said that it does not pass through Ga. Therefore, Example 1
A carrier a-degree distribution that is approximately the same as that obtained is obtained.

(Example 3) FIG. 6 is a sectional view showing the @3 embodiment of the present invention.

In this embodiment, a nitrogen-rich metal silicide film 13 is deposited on the surface of an insulating GaAS substrate 11 with an insulating film 16 interposed therebetween. Here, the insulating film 16 is made of SiO2,5i
xN4, etc., but when forming these films by ion implantation, sputtering, CVD, etc. after forming these films, As, which has a high vapor pressure among the elements constituting GaAg, is used. It's doping. The As concentration may be about 1015 to 1010 l9/cW13 in summer.

When the activation heat treatment of the ion implantation layer 12 is performed using the two-layer film of the doped insulating film 16 and the nitrogen-containing metal silicide film 13 as a heat treatment protective film, the metal silicide film 13 covering the surface of the insulating film 16 is Since M13 does not transmit the As element, As mixed in the insulating film 16 does not escape from the insulating film 16 into the atmosphere.
An effect similar to that of applying 1.A3 pressure to the substrate 11 is produced. Therefore, the carrier concentration distribution after heat treatment is almost the same as that shown in FIG. 3.

Note that if the insulating film 16 is mixed with an impurity other than As that becomes n-type or p-type with respect to GaAs, such as 5i1Sej, Zn, or Cd@, the substrate element As f
Ideal diffusion can be performed without thermal decomposition.

Of course, for a substrate such as InP or GaP, it is possible to form an i-rich metal silicon layer through a P-doped insulating film and use this as a heat treatment protective film. The same effects as described above can be obtained.

As described above for Examples 1 and 2.3, the present invention has a greater effect of suppressing the dissociation of compound conductors than conventional techniques, and in the activation heat treatment of the ion-implanted layer 12, carrier The concentration distribution curve is steep and highly concentrated, and good characteristics of A1 uniformity can be obtained with good reproducibility.

(Example 4) FIG. 7 is a sectional view showing a fourth embodiment of the present invention.

This example is an example in which diffusion heat treatment is applied to the production of a PIN photodiode using an InP substrate. In the same figure, on the n-1nP substrate 17 there are 11-111
P buffer layer 18, n--InGaAs layer 19, n-
After primary epitaxial growth of InGaAs PH20, 5i02 or Si
, N, and a metal silicide film 21B containing M containing phonemes are sequentially laminated by a stutter method, a CVO method, or the like. Next, by plasma etching or reactive ion etching using Freon gas such as CF4, the above-mentioned film 21A and metal silicide! Selectively open the two-layer film 21B and use the diffusion mask 2.
form 1.

Using this diffusion mask 21, a heat treatment is performed to diffuse a P-type element, such as Zn, until it reaches the n--1nGaAs layer 19. The heating temperature is 500 to 900°C and the time is about 10 to 100 minutes. When , the dissociation of A11 and P from the substrate occurs at the boundary between the P + diffusion layer 22 and the n InGaAap) and the diffusion mask 21 .
Since the leakage 1f at the p-n junction is suppressed by
fi (dark current as a percentage of PIN photodiode) decreases sharply.

As explained in Example 3, two types of elements, A3 and P, are implanted in advance at approximately 1010 to 1015 ions/cIn2 into 621 people forming the diffusion mask 21 by ion implantation. It is also very effective for the same reason.

The above description has been made using heat treatment that involves activation of an ion-implanted layer in a compound dry conductor substrate and selective impurity diffusion, but the present invention is also applicable to heat treatment that involves selective epitaxial growth, selective oxidation, or nitridation. Similar effects can be obtained by applying heat treatment, etc. First, when the above heat treatment is performed using a Nitrogen-containing metal silicide-rich film as a mask, the constituent elements dissociate from the compound semiconductor substrate in the masked area. can be prevented from deteriorating.

Note that the case where the compound semiconductor constitutes the substrate itself is explained above, but the present invention is not limited thereto. For example, the present invention is not limited to this. Even when applied to a compound semiconductor layer, similar @red can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, by using a metal silicide film containing nitrogen as a heat treatment protective film, the constituent elements of the compound semiconductor scraps covered with the metal silicide film are dissociated and the compound semiconductor Deterioration of the layer can be prevented, and the characteristics and manufacturing yield of a semiconductor element formed using a substrate including this compound semiconductor layer can be improved. Moreover, there is no need to handle dangerous gases such as arsine or phosphine, unlike in the capless annealing method.

In particular, when the present invention is applied to heat treatment for activating ion-implanted layers constituting the source/drain regions and channel regions of field effect transistors (FETs), threshold! The uniformity of voltage and mutual conductance is improved, and when integrated, the characteristics of each FET are uniform, so there is no need to provide a large margin for circuit operation, and high-speed operation can be realized.

In addition, the metal silicide film used as a heat treatment protective film has low resistance, so gate! Can be used as a pole.

In addition, PIN photodiode, APD (Avala
In the diffusion process for manufacturing photodiodes, etc., or in the growth process for forming a buried layer of a laser diode, the black hair 8! By performing heat treatment using the retention film as a mask, it is possible to reduce leakage current and increase sensitivity and speed of these optical devices.

Furthermore, when one ion is implanted into a multi-layered heterostructure epitaxial layer and this is heat-treated for activation, for example,
In step 5 of the high-density layer formation process using 2D electron gas to form the source and drain regions of the FET by injecting yen, more isolation can be achieved than when using 5i02 or Si3N4 films. This reduces the source series resistance and increases speed.
L. Washita, Seiko Ido (Stngle Quantvr)
n WQll, fJplti QuantumWe
ll)'& Insulating ion implantation l or p- for the laser diode and photodetector used for 76 washing layer separation.
When applied to a heat treatment process performed after ion implantation for n-junction separation, etc., the oil controllability of the ion implanted layer P/J file is improved. In addition, even in regions other than the ion-implanted layer, interdiffusion caused by thermal decomposition of the multi-layered Hera 0 structure Ebitaki/Yal layer is suppressed. 'l to be
Fit island characteristics are suppressed, and performance and reliability can be improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the first embodiment of the present invention, Figure 2 is a diagram showing the SIMS analysis results before and after heat treatment in that case, and Figure 3 is a diagram showing the carrier concentration distribution in comparison with the conventional example. FIG. 4 is a cross-sectional view showing the second embodiment of the present invention, FIG. 5 is a diagram showing the SIMS analysis results after punishment in that case, and FIGS. 8 and 9 are cross-sectional views showing the third and fourth embodiments, and FIGS. 8 and 9 are cross-sectional views showing the conventional example, and diagrams showing the results of SIMS analysis after point processing. 11.-φ.Semi-insulating GaAs substrate, 12..Ion implantation layer, 13.21B..Metal silicide layer containing nitrogen, 15,16.21A..Insulating film, 17. ... n-1nP substrate, 18・O... n
-InP buffer layer, 19@...n--InGaAs
layer, 20...n-■nGaA8P layer.

Claims (3)

[Claims] (1) A metal silicic compound containing at least nitrogen is deposited directly or via an insulating film on at least a partial region of the compound semiconductor layer of the substrate including at least one compound semiconductor layer, A method for heat treatment of a compound semiconductor, characterized by performing heat treatment. (2) A method for heat treatment of a compound semiconductor according to claim 1, characterized in that an insulating film containing at least an element having a higher vapor pressure among the elements constituting the compound semiconductor layer is used as the insulating film. . (3) The heat treatment is heat treatment accompanied by activation of an ion implantation layer in the compound semiconductor layer, heat treatment accompanied by selective impurity diffusion into the compound semiconductor layer, heat treatment accompanied by selective epitaxial growth, or heat treatment accompanied by selective oxidation or selective nitridation. A method for heat treatment of a compound semiconductor according to claim 1, characterized in that: