JP3300112B2 - Semiconductor device manufacturing method and semiconductor device manufacturing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, a method for manufacturing the same, and an apparatus for manufacturing the same. 2. Description of the Related Art In recent years, with the miniaturization and large-scale integration of semiconductor devices, there has been a problem of occurrence of defective device characteristics due to contamination on the wafer surface and deterioration of in-plane uniformity of device characteristics due to the surface state.

In particular, the surface condition of a wafer is such that the state of bonding of atoms on the surface of the wafer and the fine roughness due to irregularities at the atomic level greatly vary depending on the processing state.
It has become clear from recent advances in measuring equipment, and it has been reported that such fluctuations in the surface state of the wafer greatly affect device characteristics.

[0003]

2. Description of the Related Art In a semiconductor device manufacturing process,
Prior to the various steps, chemical treatment for exposing the semiconductor layer surface of the wafer, for example, HF treatment or the like is performed. After this HF treatment, removal and cleaning of HF or the like from the semiconductor layer surface with pure water are performed. A rinsing and drying process using a rinsing and drying device is performed.

[0004] Such a conventional washing and drying process is usually performed as follows. That is, a plurality of wafers are loaded into a rotatable wafer holder erected in a chamber, pure water is sprayed from a nozzle installed in the chamber toward the wafer surface, and the wafer is washed with water. Drying gas is sprayed from the installed nozzle toward the wafer surface to dry.

As an atmosphere gas in the chamber at the time of washing with water and a drying gas at the time of drying, dry N ₂ (nitrogen) gas having low reactivity, relatively high purity, and low cost is used. The reaction is suppressed.

[0006]

However, in the above-mentioned conventional washing and drying treatment, N ₂ gas is used as an atmosphere gas at the time of washing and a drying gas at the time of drying.
Since a natural oxide film is not formed on the surface of the wafer, the state of the surface of the wafer changes in the processing state after the rinsing and drying processing, causing a problem that the element characteristics are deteriorated and fluctuated.

In particular, when a metal electrode is formed on a compound semiconductor substrate by a sputtering method to form a Schottky junction, a natural oxide film is exposed on the surface of the compound semiconductor substrate without being formed. In addition, the surface state is affected by the atmosphere at the time of sputtering, which causes a variation in Schottky characteristics. On the other hand, after the rinsing and drying treatment, if the natural oxide film is formed by exposing the wafer surface to the atmosphere, the natural oxide film itself is non-uniform, apart from the problem of wafer surface contamination. Again, the problem that the Schottky characteristics are deteriorated and varied cannot be solved.

Accordingly, the present invention provides a semiconductor device capable of stabilizing the surface state of a semiconductor substrate, particularly a compound semiconductor substrate, and realizing improvement and stabilization of element characteristics and in-plane uniformity thereof, a method of manufacturing the same, and It is an object to provide the manufacturing apparatus.

[0009]

Means for Solving the Problems The present inventors have found that the change in the surface state of a semiconductor substrate, particularly a compound semiconductor substrate, is caused by the fact that a natural oxide film is not formed on the substrate surface during a washing and drying process. In view of the fact that even if a natural oxide film is formed, the natural oxide film itself is not uniform, and the intrinsic surface state cannot be stabilized, a thin film close to the natural oxide film is formed on the substrate surface during washing and drying. It was conceived through experiments that the surface state could be stabilized by positively forming and controlling the film thickness of the thin film and the like, and by experiments.

[0010]

[0011]

[0012]

[0013] Thus, the problem is, the compound semiconductor substrate surface washed by pure water, in the manufacturing method of a semiconductor device for drying by the drying gas, as an atmospheric gas during washing of said compound semiconductor substrate surface, or the
As the drying gas during drying of the compound semiconductor substrate surface, using a reactive gas and low reactive gas or mixed gas of a non-reactive gas, into the compound semiconductor substrate surface, and the compound semiconductor substrate of the mixed gas This is achieved by a method for manufacturing a semiconductor device, wherein a thin film is formed by a reaction with the reactive gas.

In the above method for manufacturing a semiconductor device, it is desirable to control a flow rate and a mixing ratio of the reactive gas. In the method for manufacturing a semiconductor device, the reactive gas is oxygen gas, the low-reactive gas is nitrogen gas, and the non-reactive gas is argon gas, neon gas, helium gas, or This is achieved by a method for manufacturing a semiconductor device, which is characterized by xenon gas.

In the above-described method for manufacturing a semiconductor device, it is preferable that the mixing ratio of the oxygen gas is 5% to 80%. In the method for manufacturing a semiconductor device, it is preferable that the temperature of the compound semiconductor substrate, the pure water, or the mixed gas is controlled. Further, the object is to expose the surface of the compound semiconductor substrate, and to wash and dry the exposed surface of the compound semiconductor substrate using the method for manufacturing a semiconductor device described above, so that the compound semiconductor substrate is exposed to the compound semiconductor. A step of forming a thin film by reacting the substrate and the reactive gas in the mixed gas, and a step of forming the metal gate on the thin film, between the compound semiconductor substrate and the metal gate This is achieved by a method of manufacturing a semiconductor device, wherein a Schottky contact is formed with the thin film interposed.

Further, the above-mentioned problem is solved by using a compound semiconductor substrate.
Manufacturing for forming an oxide film of the compound semiconductor on a surface
An apparatus, a wafer holder that holds the compound semiconductor substrate, a chamber in which the wafer holder is provided, a nozzle that is installed in the chamber, and that injects pure water or gas onto the surface of the compound semiconductor substrate, The present invention is achieved by an apparatus for manufacturing a semiconductor device, characterized by having a gas supply source for supplying a reactive gas, a low- reactive gas, and a non-reactive gas to a nozzle.

In the above-described apparatus for manufacturing a semiconductor device, the apparatus is provided between the gas supply source and the nozzle, and controls the flow rates of the reactive gas, the low-reactive gas, and the non-reactive gas. It is desirable to have gas flow control means. In the above-described semiconductor device manufacturing apparatus,
It is preferable that a gas mixing unit is provided between the gas supply source and the nozzle and mixes the reactive gas with the low-reactive gas or the non-reactive gas.

Further, in the apparatus for manufacturing a semiconductor device, controls the compound temperature of the atmosphere in said chamber for containing the semiconductor substrate, or the temperature of the pure water or the mixed gas is injected into the compound semiconductor substrate surface It is desirable to have temperature control means. In the above-described apparatus for manufacturing a semiconductor device, it is preferable that the apparatus further includes a wafer holder rotating unit that rotates the wafer holder that holds the compound semiconductor substrate in the chamber.

The term “semiconductor substrate or compound semiconductor substrate” as used herein means not only a case where the whole substrate is made of a semiconductor or a compound semiconductor but also a case where a semiconductor layer or a compound semiconductor layer is formed on an insulating substrate or a semi-insulating substrate. It is also included when it is done.

[0020]

According to the present invention, in a semiconductor device manufacturing apparatus,
A nozzle for injecting pure water or a mixed gas containing a reactive gas is installed in a chamber in which a semiconductor substrate holder for loading a semiconductor substrate is installed, so that pure water is introduced toward the semiconductor substrate surface. Pure water can be sprayed from the nozzle to wash, and a mixed gas containing a reactive gas can be used as an atmosphere gas during the washing or a dry gas after the washing.

Therefore, in the method of manufacturing a semiconductor device,
When performing the washing and drying treatment of the semiconductor substrate surface using the above apparatus, by using a mixed gas containing a reactive gas as an atmosphere gas at the time of washing or a dry gas after the washing, the semiconductor substrate and the reactive gas are mixed. A thin film can be formed on the surface of the semiconductor substrate by the reaction. And with this thin film,
Since the surface state of the semiconductor substrate can be stabilized, the stability of the characteristics of the semiconductor element formed through the manufacturing process after the washing and drying treatment can be improved.

When such a washing and drying treatment of the surface of the semiconductor substrate is applied to a pretreatment for forming a Schottky electrode of the compound semiconductor device, a thin film is formed on the compound semiconductor substrate, and the thin film is formed on the compound semiconductor substrate and the metal gate. By realizing the Schottky contact interposed between, the surface state of the compound semiconductor substrate is stabilized by the thin film,
Improvement and stabilization of Schottky characteristics can be realized.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the illustrated embodiments. FIG. 1 is a schematic sectional view showing a washing and drying apparatus according to a first embodiment of the present invention. A wafer holder 14 for loading a plurality of wafers 12 into the chamber 10;
Has been erected. And this wafer holder 14
It is configured to be rotated by a motor 16 installed outside the chamber 10.

In the chamber 10, a gas introduction nozzle 18a and a pure water introduction nozzle 18b are provided.
The gas introduction nozzle 18a is connected to a gas mixer 20, and the gas mixer 20 includes filters 22a, 22b,
22c, flow meters 24a, 24b, 24c, and flow control valves 26a, 26b, 26c, respectively.
_{2 It is connected to an} (oxygen) gas supply source, a N ₂ gas supply source, and an Ar (argon) gas supply source (all not shown). The pure water introduction nozzle 18b is provided with a filter 22d,
It is connected to a pure water supply source (not shown) via a flow meter 24d and a flow control valve 26d.

The O ₂ gas is a reactive gas having a high activity, the N ₂ gas is a low reactive gas having a low activity,
r gas is an inert, non-reactive gas. Also, a Ne (neon) gas instead of Ar gas as a non-reactive gas,
He (helium) gas or Xe (xenon) gas may be used. Further, a gas heater 28a for heating the mixed gas is provided between the gas introduction nozzle 18a and the gas mixer 20. Similarly, a pure water heater 28b for heating pure water is provided between the pure water introduction nozzle 18b and the filter 22d. Further, a chamber heater 30 for heating the atmosphere in the chamber 10 and controlling the temperature of the wafer 12 in the chamber 10 is provided adjacent to the chamber 10.

Next, a method of washing and drying the wafer 12 using the washing and drying apparatus of FIG. 1 will be described with reference to FIG. For example, the surface of the wafer 12 that has been exposed and cleaned by chemical treatment with HF or the like is subjected to rinsing and drying processing using the rinsing and drying apparatus of FIG. 1 after removing HF and the like by pure water cleaning. Such processing is repeatedly performed in a wafer wet processing step in a semiconductor device manufacturing process.

First, a mixed gas 32 of O ₂ gas and N ₂ gas or Ar gas is injected from the gas introduction nozzle 18a.
The chamber 10 is filled up. At this time, the mixed gas 3
2 is an O ₂ gas supply source, an N ₂ gas supply source, and Ar
The gas is supplied from a gas supply source and the flow control valves 26a, 26
b, 26c and the flow meters 24a, 24b, 24c control the flow rate, and reach the gas mixer 20 through the filters 22a, 22b, 22c. And this gas mixer 2
After being mixed at a predetermined mixing ratio at 0, the mixture is supplied to the gas introduction nozzle 18a.

[0028] Incidentally, the combination of the mixed gas, the other three kinds mixed with Ar gas as N ₂ gas and a non-reactive gas as O ₂ gas and low reactive gas as a reactive gas, O ₂ gas and two mixing of N ₂ gas, may be two kinds mixed with O ₂ gas and Ar gas. However, in any case, it is necessary to contain 5% to 80% of O ₂ gas. The combination of these mixed gases and their mixing ratio are determined based on the thickness of the oxide thin film to be formed and the like.

The temperature of the mixed gas 32 and the temperature of the chamber 1
0, the temperature of the atmosphere in
The temperature is controlled to a desired temperature by a and the heater 30 for the chamber. Next, the plurality of wafers 12 are loaded into the wafer holder 14, and the wafer holder 14 is further installed in the chamber 10. And this wafer holder 14
While the wafer 12 is loaded, the motor 16
To rotate.

Subsequently, as shown in FIG. 2A, pure water 34 is jetted from the pure water introduction nozzle 18b toward the surface of the wafer 12 to perform cleaning. At this time, this pure water 34
Is supplied from a pure water supply source and its flow rate is controlled by a flow control valve 26d and a flow meter 24d.
d to the pure water introduction nozzle 18b. Further, the temperature of the pure water 34 is controlled to a desired temperature by the pure water heater 28b.

Incidentally, the wafer 1 is supplied from the pure water introduction nozzle 18b.
Even when the pure water 34 is sprayed toward the two surfaces,
As shown in FIG. 2A, the injection of the mixed gas 32 from the gas introduction nozzle 18a is continued. Therefore, the mixed gas 32 becomes an atmosphere gas when the surface of the wafer 12 is washed with water. Next, when the washing is completed, the injection of the pure water 34 from the pure water introduction nozzle 18b is stopped, but the injection of the mixed gas 32 from the gas introduction nozzle 18a is further continued. Thus, as shown in FIG. 2B, the mixed gas 3 directed from the gas introduction nozzle 18a toward the surface of the wafer 12
By the injection of 2, the pure water 34 on the surface of the wafer 12 is removed and dried. That is, the mixed gas 32 becomes a drying gas for drying the surface of the wafer 12 after the water washing from the atmosphere gas at the time of the water washing. At this time, the mixing ratio of the mixed gas 32 is
It may be as it is or may be changed.

Next, when the drying is completed, the injection of the mixed gas 32 from the gas introducing nozzle 18a is stopped, but the atmosphere gas at the time of washing and the drying gas at the time of drying after washing are as follows.
Since a mixed gas 32 containing O ₂ gas is used, FIG.
As shown in (c), the material of the wafer 12 reacts with the O ₂ gas on the surface of the wafer 12 to form an oxide thin film 36 close to a natural oxide film formed in an air atmosphere.

As described above, according to the present embodiment, the O ₂ gas and the N ₂ gas or the Ar gas are placed in the chamber 10 in which the plurality of wafers 12 are loaded and the wafer holder 14 rotated by the motor 16 is installed. Using a washing / drying apparatus provided with a gas introduction nozzle 18a for injecting a mixed gas with the pure water and a pure water introduction nozzle 18b for injecting pure water, the pure water introduction nozzle 18b is directed toward the rotating wafer 12 surface. Pure water 34 is sprayed and washed, and a mixed gas 32 containing O ₂ gas is used as an atmosphere gas at the time of the washing. After the washing, the mixed gas 32 is directed from the gas introduction nozzle 18a to the surface of the rotating wafer 12. as the drying gas for jetting to dry, O ₂ by using a mixed gas 32 containing gas, child forming an oxide film 36 on the wafer 12 surface Can.

At this time, an O ₂ gas and an N ₂ gas or an Ar gas as an atmosphere gas at the time of washing and a drying gas after the washing are used.
By controlling the mixing ratio of the mixed gas 32 with the gas using the gas mixer 20 or the like, the thickness of the oxide thin film 36 formed on the surface of the wafer 12 can be controlled. Also,
The gas heater 28a, the pure water heater 28b, and the chamber heater 30 are used to control the temperature of the mixed gas, the pure water, and the temperature of the wafer 12 to be sprayed toward the surface of the wafer 12, so that the surface of the wafer 12 is also controlled. The thickness and the like of the oxide thin film 36 to be formed can be controlled.

The wafer 12 having such a controlled film thickness or the like
Since the surface state of the wafer 12 can be stabilized by the presence of the oxide thin film 36 on the surface, the stability of the characteristics of the semiconductor element formed through the manufacturing process after the washing and drying process and the uniformity within the wafer surface are improved. And thus the performance, reliability, and manufacturing yield of the device.

Next, a washing / drying apparatus according to a second embodiment of the present invention will be described with reference to a schematic sectional view shown in FIG.
The same components as those in the washing / drying apparatus of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. This second embodiment is:
Instead of the gas introduction nozzle 18a and the pure water introduction nozzle 18b which are separately provided in the first embodiment,
It is characterized in that a nozzle serving both functions is provided.

That is, the mixed gas and pure water introduction nozzle 18c is provided in the chamber 10. The mixed gas / pure water introduction nozzle 18c is connected to a gas mixer 20 and a pure water filter 22d via a switching valve 38, respectively. A mixed gas / pure water heater 28c for heating the mixed gas / pure water is installed between the mixed gas / pure water introduction / nozzle 18c and the switching valve 38.

In the washing and drying process of the wafer using the washing and drying apparatus, first, before the wafer 12 is loaded into the wafer holder 14, the switching valve 38 is switched so that the mixed gas passes therethrough. Then, the mixed gas 32 is injected from the pure water introduction / combination nozzle 18 c to fill the chamber 10. Next, after the wafer 12 is loaded, the switching valve 38 is switched so that pure water passes therethrough, and cleaning is performed by injecting the pure water 34 from the mixed gas and pure water introduction / purpose nozzle 18c.

Next, when the washing is completed, the switching valve 38 is switched again so that the mixed gas passes therethrough, and the injection of the mixed gas 32 is stopped by stopping the injection of the pure water 34 from the mixed gas / pure water introduction combined nozzle 18c. To start. In this manner, the wafer 12
The pure water 34 on the surface is removed and dried. As described above, according to the present embodiment, the mixed gas / pure water introduction nozzle 18c is provided instead of the gas introduction nozzle 18a and the pure water introduction nozzle 18b in the first embodiment, so that the chamber 10 The size of the washing / drying apparatus can be reduced by simplifying the inside, and the same effect as that of the first embodiment can be obtained.

Next, the GaAs according to the third embodiment of the present invention will be described.
s-MESFET (Metal-Semiconductor Field-Effect
Transistor) will be described with reference to a cross-sectional view shown in FIG. An n-impurity layer 46a to which Mg is added is formed on the surface of the semi-insulating GaAs substrate 40. Also, this n
The surface of the impurity layer 46a has p
⁺ -Source region 54 and p ⁺ -drain region 56 are formed to face each other. Furthermore, these p ⁺ -source regions 5
On the surface of n-impurity layer 46a sandwiched between p-channel layer 4 and p ⁺ -drain region 56, p-channel layer 48 doped with Si is formed.
b is formed.

Then, on the p-channel layer 48b,
By performing the washing and drying treatment as shown in FIG. 2 using the washing and drying apparatus shown in FIG. 1, the thickness of the p-channel layer 48b is reduced by the reaction between GaAs on the surface of the p-channel layer 48b and O ₂ gas in the mixed gas. The GaAs film according to the present embodiment is characterized in that an oxide thin film 50 composed of a Ga ₂ O ₃ thin film, a Ga ₂ O ₅ thin film, an As ₂ O ₃ thin film, an As ₂ O ₅ thin film, etc.
-Features of MESFET.

On the oxide thin film 50, for example, W
A 500-nm-thick gate electrode 52 made of Si, W, Al, or the like is formed, and is in Schottky contact with the p-impurity layer 48a via the oxide thin film 50. The p ⁺ -source region 54 and the p ⁺ -drain region 5 are formed through openings selectively provided in the SiN film 58 as a surface protection film.
6, a source electrode 60 and a drain electrode 62 made of, for example, AuGe, which are in ohmic contact with each other, are formed.

Next, a method of manufacturing the GaAs-MESFET shown in FIG. 4 will be described with reference to the process charts shown in FIGS. On the semi-insulating GaAs substrate 40, for example, a 20 nm-thick SiN film 42 is formed as a surface protection film.
(A)). Next, after applying a resist 44 on the entire surface, patterning for opening an element region is performed. Then, using the patterned resist 44 as an implantation mask,
The ion implantation of Mg and Si is performed, and the Mg ion implantation layer 4 is formed.
6 and a Si ion implantation layer 48 are formed. At this time, the conditions for the ion implantation of Mg were an acceleration voltage of 200 keV and a dose of 1 × 10 ¹² cm ⁻² , and the conditions for the ion implantation of Si were an acceleration voltage of 50 keV and a dose of 5 × 10 ¹² cm ⁻² (FIG. 5 (b)).

Next, after removing the resist 44, an annealing process for activating the implanted Mg ions and Si ions is performed. At this time, the annealing condition is set at a temperature of 30.
0 ° C., time 20 minutes. Thus, the Mg ion implanted layer 46 and the Si ion implanted layer 48 become an n-impurity layer 46a and a p-impurity layer 48a, respectively (see FIG. 5C).

Next, the SiN film 42 is removed by using, for example, HF or the like to expose the surfaces of the semi-insulating GaAs substrate 40 and the p-impurity layer 48a, and after cleaning, the HF or the like is removed by pure water cleaning. . Subsequently, using the washing and drying apparatus shown in FIG. 1, a washing and drying process of injecting a mixed gas containing O ₂ gas onto the surface of the semi-insulating GaAs substrate 40 as shown in FIG. The processing conditions at this time were a mixed gas obtained by adding 20% of reactive O ₂ gas to low-reactive N ₂ gas. In addition, mixed gas, pure water, and semi-insulating G
The temperature of the aAs substrate 40 was set to 40 ° C., respectively.

Thus, the semi-insulating GaAs substrate 40 and p
- injecting a mixed gas containing O ₂ gas to the impurity layer 48a surface, and O ₂ gas reaction in the mixed gas to the GaAs dangling bonds on the surface of a thickness of several nm Ga ₂ O ₃ thin film or As ₂ O _Three
An oxide thin film 50 composed of a thin film is formed. Subsequently, a 500 nm-thick WSi layer is deposited on the entire surface by sputtering, and then patterned into a predetermined shape. In addition, this W
The RIE (Reactive Ion Etching) method using SF ₆ as an etching gas was used for patterning the Si layer. In this way, a gate electrode 52 made of a WSi layer that is in Schottky contact with the oxide thin film 50 is formed on the p- impurity layer 48a (see FIG. 6D).

Next, using the gate electrode 52 as a mask,
Si ions are implanted under the conditions of an acceleration voltage of 100 keV and a dose of 1 × 10 ¹³ cm ⁻² . Subsequently, annealing is performed at a temperature of 750 ° C. for a time of 30 minutes to activate the implanted Si ions. Thus, the p ⁺ -source region 54 and the p ⁺ -drain region 5 whose depths reach from the p- impurity layer 48a to the n- impurity layer 46a.
6 are formed on both sides of the gate electrode 52. This gives p
^The p − impurity layer 48 a sandwiched between the ⁺ − source region 54 and the p ⁺ − drain region 56 becomes the p − channel layer 48 b (see FIG. 6E).

Next, an Si film as a surface protection film is formed on the entire surface.
An N film 58 is formed. Subsequently, after a resist is applied to the entire surface, patterning for providing openings above the p ⁺ -source and drain regions 54 and 56 is performed. Then, using this patterned resist as a mask, the SiN film 42 on the p ⁺ -source and drain regions 54 and 56 is selectively etched to expose the surfaces of the p ⁺ -source and drain regions 54 and 56 and For example, an Au / AuGe layer is deposited. Subsequently, by lifting off the resist,
Au / is formed only on the p ⁺ -source and drain regions 54 and 56.
The AuGe layer is left. Using such a lift-off method, the source electrode 60 made of Au / AuGe in ohmic contact on the p ⁺ -source / drain regions 54 and 56
Then, a drain electrode 62 is formed (see FIG. 6F).

Next, the characteristics of the GaAs-MESFET of FIG. 4 will be described with reference to FIG. FIG. 7 shows the GaAs of FIG.
13 is a graph showing characteristics of a Schottky diode forward operating voltage Vf when a voltage is applied between the gate electrode 52 and the source electrode 60 or the drain electrode 62 of the MESFET. For comparison, the characteristics of the forward operating voltage Vf when an oxide thin film is not formed between the p-channel layer 48b and the gate electrode 52 are also shown.

As is apparent from the graph of FIG.
-In the case of the present embodiment in which the oxide thin film 50 is formed between the channel layer 48b and the gate electrode 52, the forward operating voltage Vf has a variation of ± 30 mV around Vf = 0.57V. . On the other hand, in the conventional case in which the oxide thin film is not formed, a variation of ± 40 mV occurs around Vf = 0.51V.

From the comparison between the two, the formation of the oxide thin film 50 between the p-channel layer 48b and the gate electrode 52 increases the forward operating voltage Vf by about 60 mV and reduces the variation thereof. You can see that.
That is, the Schottky characteristics are improved and stabilized. This is because the existence of the oxide thin film 50 is
-It is considered that this is because the surface state of the channel layer 48b is stabilized.

As described above, according to the present embodiment, in the pre-treatment step immediately before the formation of the gate electrode 52, the surface of the base p-impurity layer 48a is exposed using HF or the like, and then the rinsing and drying processing is performed. Using the washing and drying device shown in FIG.
By performing the washing and drying treatment in which the mixed gas containing the O ₂ gas as shown in FIG. 2 is sprayed onto the surface of the p-impurity layer 48a, the GaAs on the surface of the p-impurity layer 48a reacts with the O ₂ gas to oxidize. Since the thin film 50 is formed, a Schottky contact with the oxide thin film 50 interposed between the p-channel layer 48b and the gate electrode 52 can be formed, and therefore, the improvement and stabilization of the Schottky characteristics are realized. can do.

Next, the relationship between the type of mixed gas used in the rinsing and drying process before the formation of the gate electrode 52 of the GaAs-MESFET in FIG. 4 and the Schottky characteristics of the GaAs-MESFET will be described with reference to FIG. FIG. 8 shows a pre-treatment step of forming the gate electrode 52, in which the surface of the p-impurity layer 48a is exposed using HF or the like, and then washed with water as shown in FIG. It is a graph which shows the change of the characteristic distribution of Schottky diode forward operation voltage Vf of GaAs-MESFET when the kind of mixed gas used when performing a drying process is changed.

In the graph of FIG. 8, (A) shows the forward operation in the case where the washing and drying process is performed using a mixed gas obtained by adding 20% of reactive O ₂ gas to low reactive N ₂ gas. Voltage V
It is a characteristic distribution of f. (B) shows the low reactivity of N ₂
6 is a characteristic distribution of a forward operating voltage Vf when a mixed gas obtained by adding 50% of non-reactive Ar gas to a gas is used. Further, (C) is a characteristic distribution of the forward operating voltage Vf when the water washing and drying process is performed with the conventional low-reactivity N ₂ gas 100%.

The relationship between (A) and (C) is the same as the relationship between the third embodiment shown in FIG. 7 and the conventional example. In the case of the graph of FIG. 8, the forward operating voltage Vf was shifted to a higher value by about 20 to 30 mV due to the formation of the oxide thin film between the base channel layer and the gate electrode.
In the case of (B), the shift was several mV lower than in the case of the conventional (C). This is considered to be due to the fact that the thickness of the thin film formed on the surface of the underlying channel layer became smaller due to the mixing of the non-reactive Ar gas than the case of the low-reactivity N ₂ gas of 100%.

As described above, even when the conventional washing and drying treatment is performed with 100% of low-reactivity N ₂ gas, some thin film is actually formed on the surface of the underlayer channel layer, and the forward operating voltage is reduced. It can be seen that this contributes to an increase in Vf. Therefore, a feature of the present invention is that, by adding at least 5% to 80% of a reactive gas to a gas used for washing and drying, an oxide thin film is intentionally formed, and the surface state of the underlying channel layer is stabilized. Accordingly, it is to improve and stabilize the Schottky characteristics.

The mixing ratio of the reactive gas, the low-reactive gas, and the non-reactive gas of the mixed gas used in the washing and drying treatment is as follows:
This has a great effect on the thickness of the formed oxide thin film. In particular, the mixing ratio of the reactive gas, within a certain limit,
Since the thickness of the oxide thin film tends to increase with the increase, it is desirable to determine an appropriate mixing ratio according to a desired Schottky characteristic of the GaAs-MESFET.

Next, the temperature of the mixed gas, pure water and wafer used in the washing and drying process before the formation of the gate electrode 52 of the GaAs-MESFET of FIG.
The relationship between the ET and the Schottky characteristic will be described with reference to FIG. FIG. 9 shows the gas heater 28 of the washing / drying apparatus shown in FIG. 1 after exposing the surface of the p-impurity layer 48a using HF or the like in the pretreatment step of forming the gate electrode 52.
a, a mixed gas, pure water and a GaAs-MESFET in the case of changing the temperature of the wafer used when performing the washing and drying treatment as shown in FIG. 2 using the pure water heater 28b and the chamber heater 30. 6 is a graph showing a change in a characteristic distribution of a Schottky diode forward operating voltage Vf.

In the graph of FIG. 9, (A) shows a forward operating voltage when the washing and drying process is performed at room temperature of 25 ° C. without using the gas heater 28a, the pure water heater 28b, and the chamber heater 30. It is a characteristic distribution of Vf. Also,
(B) is a gas heater 28a, a pure water heater 28b,
This is a characteristic distribution of the forward operating voltage Vf when the mixed gas, pure water, and the atmosphere in the chamber are heated using the chamber heater 30, and the washing and drying process is performed at a wafer temperature of about 40 ° C. .

As is apparent from the graph of FIG. 9, when the wafer temperature is about 40 ° C. (B), the room temperature is 25 ° C.
(A), the forward operating voltage Vf is 20 mV.
It became big. This is presumably because the increase in the wafer temperature promoted the reaction between GaAs and the O ₂ gas on the surface of the underlying channel layer, thereby forming a thicker oxide thin film. Therefore, since the temperature of the mixed gas, pure water, and the temperature of the wafer greatly affect the thickness of the oxide thin film to be formed, it is desirable to perform appropriate temperature control according to a desired Schottky characteristic of the GaAs-MESFET. .

In the third embodiment, GaAs is used.
The case where the washing and drying method using the washing and drying apparatus according to the first embodiment is applied to the method for manufacturing the GaAs-MESFET using the s substrate is described. However, the method is limited to the case of the GaAs-MESFET using the GaAs substrate. do not have to. For example, a semiconductor device using an InP substrate may be used, or (Al _X G
a _1-X ) _Y In _1-Y P _Z As _1-Z (0 ≦ X <1, 0 ≦ Y
<1, 0 ≦ Z <1) A semiconductor device using an epitaxial growth layer may be used. In these cases, the InP substrate or (Al _x Ga _{1 -x} ) _Y In _{1 -y} P _z As _{1 -z} (0 ≦ X
<1, 0 ≦ Y <1, 0 ≦ Z <1) The oxide thin film formed on the surface of the epitaxial growth layer becomes an oxide film containing a substrate element of the InP substrate, and is (Al _X Ga _{1 -X) Y} In _{1-. Y} P
_An oxide film containing the element of the ZAs1 _-Z epitaxial growth layer is obtained.

As described above, the present invention can be widely applied to the case where it is desired to stabilize the surface state of the semiconductor layer exposed in the pretreatment of a certain step.

[0063]

As described above, according to the present invention, there is provided a wafer holder for holding a semiconductor substrate, a chamber in which the wafer holder is provided, and pure water or reaction water installed in the chamber and provided on the surface of the semiconductor substrate. Having a nozzle for injecting a mixed gas of a reactive gas and a low-reactive gas or an inert gas, thereby jetting pure water from a pure water introduction nozzle toward the surface of the semiconductor substrate and washing the substrate with water. A mixed gas containing a reactive gas can be used as the atmospheric gas or the dry gas after washing with water.

For this reason, when the semiconductor substrate surface is washed with water and dried, the semiconductor substrate and the reactive gas are mixed with each other by using a mixed gas containing a reactive gas as an atmosphere gas during the washing or a dry gas after the washing. Can form a thin film on the surface of the semiconductor substrate, and the thin film can stabilize the surface state of the semiconductor substrate. In addition, the washing and drying treatment of the surface of the semiconductor substrate is applied to a pretreatment for forming a Schottky electrode of the compound semiconductor device, a thin film is formed on the compound semiconductor substrate, and the thin film is interposed between the compound semiconductor substrate and the metal gate. By realizing the Schottky contact thus performed, the surface state of the compound semiconductor substrate is stabilized by the thin film, and the Schottky characteristics can be improved and stabilized.

Therefore, in the process of washing and drying the surface of the semiconductor substrate, a thin film is intentionally formed on the surface of the semiconductor substrate, thereby stabilizing the surface state of the semiconductor substrate and improving the characteristics of the semiconductor element formed through the subsequent manufacturing steps. In order to improve the stability of the semiconductor device and the in-plane uniformity of the semiconductor substrate, the performance, reliability, and manufacturing yield of the semiconductor element can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a washing / drying apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a washing and drying treatment method using the washing and drying device of FIG. 1;

FIG. 3 is a schematic sectional view showing a washing / drying apparatus according to a second embodiment of the present invention.

FIG. 4 shows a GaAs-MES according to a third embodiment of the present invention.
FIG. 3 is a cross-sectional view showing an FET.

FIG. 5 is a process chart (1) showing a method for manufacturing the GaAs-MESFET of FIG.

FIG. 6 is a process chart (part 2) illustrating the method for manufacturing the GaAs-MESFET of FIG.

7 is a graph showing characteristics of a Schottky diode forward operating voltage Vf of the GaAs-MESFET of FIG. 4;

FIG. 8 is a graph showing a change in the characteristic distribution of the Schottky diode forward operating voltage Vf of the GaAs-MESFET when the type of mixed gas used for the washing and drying processing is changed.

FIG. 9 shows a GaAs-MESFE when the temperature of a mixed gas, pure water, and a wafer used in the washing and drying treatment is changed.
7 is a graph showing a change in a characteristic distribution of a Schottky diode forward operating voltage Vf of T.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Chamber 12 ... Wafer 14 ... Wafer holder 16 ... Motor 18a ... Gas introduction nozzle 18b ... Pure water introduction nozzle 18c ... Nozzle for mixed gas and pure water introduction 20 ... Gas mixer 22a, 22b, 22c, 22d ... Filter 24a, 24b, 24c, 24d: Flowmeters 26a, 26b, 26c, 26d: Flow control valve 28a: Gas heater 28b: Pure water heater 28c: Mixed gas and pure water combined heater 30: Chamber heater 32: Mixed gas 34 ... Pure water 36 ... Oxide thin film 38 ... Switching valve 40 ... Semi-insulating GaAs substrate 42 ... SiN film 44 ... Resist 46 ... Mg ion implantation layer 46a ... n-impurity layer 48 ... Si ion implantation layer 48a ... p-impurity layer 48b ... ... p-channel layer 50 ... oxide film 52 ... gate electrode 54 p ⁺ - source territory 56 ... p ⁺ - drain region 58 ... SiN film 60 ... Source electrode 62 ... drain electrode

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuya Oizumi 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Masaaki Kuno 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited ( 56) References JP-A-4-132232 (JP, A) JP-A-5-129342 (JP, A) JP-A-6-252178 (JP, A) JP-A-8-83811 (JP, A) Tribologist , Japan, Vol. 3, p. 42−48 (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/338 H01L 29/812 H01L 21/31 H01L 21/316 H01L 29/872 H01L 21/304 651

Claims (11)

(57) [Claims] The method according to claim 1 The compound semiconductor substrate surface washed by pure water, in the manufacturing method of a semiconductor device for drying by the drying gas, as an atmospheric gas during washing of said compound semiconductor substrate surface, or drying of the compound semiconductor substrate surface As the dry gas at the time, using a mixed gas of a reactive gas and a low-reactive gas or a non-reactive gas, on the compound semiconductor substrate surface, the compound semiconductor substrate and the reactive gas in the mixed gas A method for manufacturing a semiconductor device, wherein a thin film is formed by a reaction. 2. The method for manufacturing a semiconductor device according to claim 1 , wherein a flow rate and a mixing ratio of the reactive gas are controlled. 3. The method for manufacturing a semiconductor device according to claim 1 , wherein the reactive gas is an oxygen gas, the low-reactive gas is a nitrogen gas, the non-reactive gas is an argon gas, A method for manufacturing a semiconductor device, comprising a neon gas, a helium gas, or a xenon gas. 4. A method of manufacturing a semiconductor device according to claim 2 or 3, the method of manufacturing a semiconductor device mixing ratio of the oxygen gas, characterized in that 5% to 80%. 5. The method for manufacturing a semiconductor device according to claim 1 , wherein a temperature of the compound semiconductor substrate, the pure water, or the mixed gas is controlled. A step of exposing the 6. The compound semiconductor substrate surface, using the method of manufacturing a semiconductor device according to any one of claims 1 to 5, washed with water dried and exposed the compound semiconductor substrate surface, said compound A step of forming a thin film on the surface of a semiconductor substrate by a reaction between the compound semiconductor substrate and the reactive gas in the mixed gas; and a step of forming the metal gate on the thin film; Forming a Schottky contact with the thin film interposed between the semiconductor device and the metal gate. 7. The method according to claim 7 , wherein the compound is provided on a surface of the compound semiconductor substrate.
A manufacturing apparatus for forming an oxide film of a semiconductor , comprising: a wafer holder for holding the compound semiconductor substrate; a chamber in which the wafer holder is provided; and a wafer installed in the chamber and having a pure surface on the surface of the compound semiconductor substrate. An apparatus for manufacturing a semiconductor device, comprising: a nozzle that injects water or a gas; and a gas supply source that supplies a reactive gas, a low- reactive gas, and a non-reactive gas to the nozzle. 8. The apparatus for manufacturing a semiconductor device according to claim 7 , wherein the flow rate of the reactive gas, the low reactive gas, and the non-reactive gas is provided between the gas supply source and the nozzle. An apparatus for manufacturing a semiconductor device, comprising: a gas flow rate control means for controlling the pressure. 9. The apparatus for manufacturing a semiconductor device according to claim 7 or 8, wherein disposed between the gas source and said nozzle, said reactive gas less reactive gas or the non-reactive gas A semiconductor device manufacturing apparatus comprising a gas mixing means for mixing the semiconductor device and the semiconductor device. 10. A semiconductor device manufacturing apparatus according to claim 7, wherein the compound temperature of the atmosphere in said chamber for containing the semiconductor substrate, or the temperature of the pure water or the mixed gas is injected into the compound semiconductor substrate surface An apparatus for manufacturing a semiconductor device, comprising: temperature control means for controlling the temperature. 11. The semiconductor device manufacturing apparatus according to claim 7 , further comprising a wafer holder rotating means for rotating said wafer holder holding said compound semiconductor substrate in said chamber. .