JPH11145232A - Manufacturing-process evaluating method of compound semiconductor device, and process evaluating pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure simply and accurately the oxidation quantity of a compound semiconductor material, by applying the process with the same condition as its manufacturing process to a material with a faster oxidation speed than it, and by measuring the variation of the electric resistance of the material. SOLUTION: Growing epitaxially on a semi-insulating GaAs substrate 1 by an MBE method, etc., an n-type AlAs layer 2 using AlAs with a larger oxidation rate than GaAs, a protective film 3 is formed thereafter. Removing one-portions of the protective film 3 and an oxidation layer 4 by etching them, electrodes 5, 6 are formed by a lift-off method to complete a manufacture evaluating pattern. Hereupon, when denoting the thickness of the n-type AlAs layer 2 by d, the thickness of the oxidation layer 4 by X, the widths of the electrodes 5, 6 by W, and the distance between the electrodes 5, 6 by L, the value of a resistance R therebetween is represented by R=ρL/W(d-X). Measuring for AlAs previously the correlation of its electric resistance to its oxidation quantity, the electric resistance measured for an arbitrary manufacturing process is compared with the correlation to make measurable the oxidation quantity of AlAs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating a semiconductor device manufacturing process and an evaluation pattern for easily performing the evaluation, and more particularly to a method for evaluating a semiconductor device manufacturing process using a compound semiconductor material. This is related to the evaluation pattern to be performed.

[0002]

2. Description of the Related Art Gallium arsenide (GaAs), aluminum gallium arsenide (AlxGa1-xAs), indium gallium arsenide (InxGa1-xAs), a mixed crystal system of gallium arsenide and aluminum arsenide (AlAs), indium arsenide (InAs), etc. The compound semiconductor material of
Since the mobility of electrons is higher than that of silicon (Si), a field-effect transistor (F
ET) and heterojunction bipolar transistors (HB
Research and development of high-output devices and integrated circuits in the microwave and millimeter wave bands according to T) have been actively conducted. FIG. 10B shows a GaAs FET as an example of such a compound semiconductor device.
10A is a plan view of a semiconductor chip for explaining the structure of FIG. 10, and FIG. 10A is a cross-sectional view taken along the line AA ′ of FIG. The figure shows MESFET (Metal-Semico)
nductor Field Effect Tran
2 shows a (sistor) type FET. As shown in FIG. 10, the GaAs FET includes a semi-insulating GaAs substrate 1 and n
Active layer 15 of n-type GaAs, ohmic contact layer 16 of n-type GaAs, gate electrode 17 of WSi, and drain electrode 1 of AuGe / Ni
8, a source electrode 19, and a protective film 20 made of Si02.

[0003] In these compound semiconductor devices, an insulating film such as Si02, SiNx or polyimide is used as a protective film on the semiconductor surface, and an insulating film / semiconductor interface is formed in an active part of the element. It is known that at the interface of such a protective film, a transition layer in which a natural oxide film of a semiconductor or an insulating film and a semiconductor are mixed by mutual diffusion is formed. It is considered that such a crystal defect in the transition layer acts as a charge trap, so that device characteristics become unstable. In particular, in a GaAs-based compound semiconductor, when the semiconductor surface is oxidized, the vapor pressures of Ga oxide and As oxide are different.
The / As composition ratio changes, and accordingly, the element breakdown voltage changes as shown in FIG. Therefore, in order to make the device breakdown voltage uniform within the wafer surface or between lots, it is necessary to strictly control the degree of oxidation of the semiconductor surface when the protective film is formed. Oxidation of the semiconductor surface occurs when the semiconductor reacts with oxygen gas or water in the film forming equipment at the initial stage of film formation of the protective film, but to the extent that a natural oxide film remains on the wafer surface before film formation. There is a correlation with complicated factors such as the state of the film and the ultimate vacuum in the film forming apparatus. For this reason, it is extremely difficult to predict the degree of oxidation of the semiconductor surface from the process conditions. In general, after forming a protective film under the same conditions as in the device fabrication process, the cross section near the protective film / semiconductor interface is observed by TEM or the like. A method of observing and measuring the thickness of a transition layer (oxide layer) formed by oxidation of a semiconductor surface is used.

[0004]

However, when the thickness of the oxide layer is measured by the above-described method, the following problems occur. First, the thickness of the oxide layer at the protective film / semiconductor interface to be measured is at most about 1 to 2 nm in the case of GaAs. Therefore, it is necessary to use a high-magnification electron microscope such as a TEM for the measurement. In observation with an electron microscope,
The sample thickness must be set to about 0.1 μm, and a complicated process such as ion milling is required to prepare an observation sample. Also,
Damage is also introduced into the protective film / semiconductor interface portion to be observed by ion milling, which changes the thickness and composition of the oxide layer, thus making it impossible to perform accurate measurement. Further, since the change in the element breakdown voltage due to the oxidation of the semiconductor surface as described above is extremely sensitive, the thickness of the oxide layer at the interface of the protective film must be measured with an accuracy of about 0.1 nm. It is.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple and highly accurate method for oxidizing a semiconductor surface using a compound semiconductor material. An object of the present invention is to provide an evaluation method for measuring an amount. A second object of the present invention is to provide an evaluation pattern for easily evaluating the above-described method for evaluating a semiconductor device manufacturing process.

[0006]

In order to solve the above-mentioned problems, a method for evaluating a manufacturing process of a compound semiconductor device according to claim 1 of the present application uses the method for evaluating a material having a higher oxidation rate than the compound semiconductor material. A manufacturing process is performed under the same conditions as the manufacturing process, and a change in electric resistance of the material having a high oxidation rate after the completion of the manufacturing process is measured. Further, the method for evaluating a manufacturing process of a compound semiconductor device according to claim 2 of the present application includes a step of epitaxially growing a stacked structure including a material having a higher oxidation rate than the compound semiconductor material, and the step of etching the material having a higher oxidation rate by etching. The method is characterized in that a mesa pattern is formed so as to be exposed on the side surface, and a change in electric resistance of the mesa pattern containing the material having a high oxidation rate after the production process is measured.

According to a third aspect of the present invention, there is provided a method of evaluating a manufacturing process of a compound semiconductor device, comprising the steps of: epitaxially growing a laminated structure containing a material having an oxidation rate higher than that of the semiconductor material; A mesa pattern including a material having a high oxidation rate is completed after a manufacturing process including a step of forming a mesa pattern in which a fast material is exposed on a side surface and a step of forming a protective film under the same conditions as the manufacturing process. It is characterized by measuring a resistance change. The method for evaluating a manufacturing process of a compound semiconductor device according to claim 4 of the present application is the same as the method for evaluating a manufacturing process for a compound semiconductor device according to claims 1 to 3,
It is characterized in that the group III element of the compound semiconductor material is Ga and the substance having a high oxidation rate is a compound semiconductor material using Al as the group III element. Further, an invention according to claim 5 of the present application is a process evaluation pattern used for evaluating a manufacturing process of a compound semiconductor device, wherein the semiconductor material is used for measuring an oxidation amount of the compound semiconductor material by the manufacturing process. Also has a mesa-type structure such that the material having a high oxidation rate is exposed on the side surface, and is constituted by a plurality of stripe-shaped patterns having different widths. Features.

According to the process evaluation method of the present invention, first, the resistance of a material having a high oxidation rate is measured, and based on the amount of change,
Obtain the oxidation amount of the material having a high oxidation rate. For this reason, the measured amount is an electric resistance, and a complicated high-magnification morphological observation such as a TEM is not required, so that the evaluation process can be simplified. Further, the amount of oxidation of the semiconductor material can be measured while being enlarged. Next, the oxidation amount of the semiconductor material is determined from the oxidation amount of the obtained material having a high oxidation rate. Since the ratio of the surface oxidation rate is constant between the semiconductor material whose oxidation amount is desired to be determined and the material having a high oxidation rate, the oxidation amount of the material having a high oxidation rate obtained from the resistance change amount is multiplied by a constant, The oxidation amount of the semiconductor can be obtained with high accuracy. Further, since the process evaluation pattern of the present invention is composed of a plurality of stripe-shaped patterns having different widths, the amount of oxidation from the side of the mesa can be easily evaluated simply by measuring the presence or absence of conduction. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
This will be described with reference to the drawings. FIGS. 1A to 1C are cross-sectional views in the order of steps showing a manufacturing process evaluation pattern creation method of a compound semiconductor manufacturing process evaluation method according to an embodiment of the present invention. The production process evaluation pattern is prepared by first forming an n-type AlAs layer 2 using AlAs having a higher oxidation rate than GaAs by epitaxial growth on a semi-insulating GaAs substrate 1 by MBE or the like, and then forming a protective film 3. . The conditions for forming the protective film 3 are evaluated by manufacturing process evaluation.
The same conditions as in the aAsFET fabrication process are used. Thus, an oxide layer 4 is formed at the interface between the AlAs layer 2 and the protective film 3. Next, as shown in FIGS. 1B and 1C,
After a predetermined mask pattern is formed using a photoresist or the like, a part of the protective film 3 and the oxide layer 4 are removed by etching, and the electrodes 5 and 6 are formed by a lift-off method or the like, thereby completing a manufacturing evaluation pattern.

When the electric resistance between the electrodes 5 and 6 of the production evaluation pattern is measured, the result shown in FIG. 2 is obtained. As shown in FIG. 1, when the thickness of the AlAs layer 2 is d, the thickness of the oxide layer 4 is X, the width of the electrodes 5 and 6 is W, and the distance between the electrodes 5 and 6 is L, the resistance is The value R is expressed as follows. R = ρ
L / W (dX) As described above, if the correlation between the participation fee and the resistance value for AlAs as shown in FIG. 2 is measured in advance, the electric resistance obtained for an arbitrary manufacturing process can be calculated as shown in FIG. By comparing with, the oxidation amount of AlAs can be obtained.

Next, the oxidation amount of GaAs is calculated from the oxidation amount of AlAs obtained by measuring the electric resistance between the electrodes 5 and 6 as described above. As shown in FIG.
If the oxidation amount of As is about 50 μm or less, the oxidation amount of AlAs d [AlAs] and the oxidation amount of GaAs d [GaAs
s] is always constant. Therefore, if the correlation between the oxidation amount of AlAs and the oxidation amount of GaAs with respect to the oxidation time as shown in FIG. 3 is measured in advance, the oxidation amount of GaAs can be calculated from the oxidation amount of AlAs for an arbitrary process.

[0012]

Next, embodiments of the present invention will be described in detail with reference to the drawings. (Embodiment 1) FIGS. 1D and 1C are a plan view and a cross-sectional view taken along line AA 'of a process evaluation pattern for explaining a process evaluation method of the present invention, respectively. FIGS. 1A to 1C are cross-sectional views in a process order for explaining a method of creating a process evaluation pattern. Referring to FIG. 1A, in order to perform a process evaluation according to the first embodiment, first, an n-type Al having a thickness d is formed on a semi-insulating GaAs substrate 1.
After the As layer 2 is epitaxially grown by MBE or the like, the protective film 3 is formed. The conditions for forming the protective film are the same as those for the GaAs FET manufacturing process for performing the process evaluation. As a result, an oxide layer 4 having a thickness X is formed at the interface between the AlAs layer 2 and the protective film 3. The oxide layer is Al2O3 and is electrically an insulator. The thickness d of the AlAs layer 2
Is suitably about 100 to 500 nm. The oxidation rate of AlAs strongly depends on the substrate temperature at the time of forming the protective film, but is about 100 nm / min at around 300 ° C. which is usually used for forming the protective film in the GaAsFET fabrication process. The time during which the surface of AlAs is oxidized is at most about 1 minute. For this reason, if the thickness of the AlAs layer is too small, the AlAs layer is entirely oxidized, and the change in resistance cannot be seen. Conversely, if the thickness is too large, the change in resistance due to oxidation of the AlAs surface becomes small, and the measurement accuracy is reduced.

Next, as shown in FIGS. 1B and 1C,
After a predetermined mask pattern is formed using a photoresist or the like, a part of the protective film 3 and the oxide layer 4 are removed by etching, and electrodes 5 and 6 are formed by a lift-off method or the like to complete an evaluation pattern. When the electrical resistance between the electrodes of the evaluation pattern manufactured as described above is measured, as shown in FIG. 2, when the oxidation state is changed, a hyperbolic change with X = d asymptote is shown. Here, L, d, shown in FIG.
The meanings of symbols such as W and X are the same as in FIGS. 1 (c) and 1 (d). The distance L between the electrodes and the width W of the electrode are arbitrary, but the influence of the leak current from the periphery of the evaluation pattern is reduced, the resistance change with respect to the oxidation amount X is made linear, and the resistance change with respect to a slight oxidation amount is measured. Therefore, it is better that W / L is large. As described above, Al as shown in FIG.
By measuring the correlation between the oxidation amount with respect to As and the resistance value, and comparing the electrical resistance obtained for an arbitrary process with FIG. 2, the oxidation amount of AlAs can be obtained.

Next, the oxidation amount of GaAs is calculated from the oxidation amount of AlAs. As shown in FIG. 3, when the oxidation amount of AlAs is about 50 μm or less, the oxidation amount d [Al
The ratio of the amount of oxidation of As] to the amount of oxidation d [GaAs] of GaAs is always constant, and d [AlAs] / d [GaAs] = about 1000. Therefore, if the correlation between d [AlAs] and d [GaAs] with respect to the oxidation time is measured in advance as shown in FIG. 3, the oxidation amount of GaAs is enlarged from the oxidation amount of AlAs for an arbitrary process. Can be evaluated. Thus, according to the process evaluation method of the present invention, A
GaAs can be easily obtained by measuring the resistance change of the lAs layer.
The amount of oxidation of the s surface can be obtained. According to this method, the amount of oxidation of the GaAs surface by the FET manufacturing process can be known only by depositing a protective film and forming electrodes using an epi-substrate in which AlAs is deposited on a GaAs substrate.

(Embodiment 2) Next, a second embodiment of the present invention will be described in detail. FIGS. 4B and 4A are a plan view and a cross-sectional view taken along line AA ′ of a process evaluation pattern used in the second embodiment, respectively. The configuration of the second embodiment is significantly different from that of the first embodiment in that two electrodes are arranged concentrically in order to eliminate the influence of leakage current from the surroundings. In the process evaluation method of the second embodiment, an evaluation pattern as shown in FIG. 4 is produced by the same method as in the first embodiment. The conditions of the fabrication process are the same as in the first embodiment. Next, when the electric resistance between the two electrodes is measured, the resistance value is AlAs
The oxidation amount x of the layer changes in a hyperbolic shape with x = d asymptote as in the first embodiment, but since one of the electrodes has a concentric electrode arrangement surrounding the other, The influence of the leak current from the periphery of the evaluation pattern is eliminated, and the change in the resistance value can be measured more precisely. Thereafter, the amount of oxidation of the GaAs surface can be obtained by the same procedure as in the first embodiment.

(Embodiment 3) Next, a third embodiment of the present invention will be described in detail. FIG. 5E is a plan view of a process evaluation pattern used in the third embodiment, and FIG.
(D) is sectional drawing of the AA 'line | wire of a process order. In the third embodiment, first, an n-type GaAs layer 7, an n-type AlAs layer 2 having a thickness d, and an n-type GaAs are formed on a semi-insulating GaAs substrate 1.
The s layer 8 is sequentially grown epitaxially by MBE or the like.
Note that an n-type GaAs substrate may be used instead of the semi-insulating substrate. In this case, the n-type GaAs layer 7 need not be grown. The n-GaAs layer is doped at a high concentration of about 1 × 10 18 cm −3 so that the resistivity is sufficiently low. Next, as shown in FIG. 5A, a predetermined mask pattern is formed with a photoresist or the like, and the n-type AlAs layer 2 and the n-type GaAs layer 8 are etched as shown in FIG. Form. After that, the protective film 3 is formed as shown in FIG. The conditions for forming the protective film are the same as those for the GaAs FET manufacturing process for performing the process evaluation. As a result, an oxide layer 4 having a thickness x is formed at the interface between the AlAs layer 2 and the protective film 3.

Next, as shown in FIG. 5D, the side wall 9 is formed by etching the protective film 3 by anisotropic dry etching. As shown in FIG. 6, the n-type GaAs layer 8 and the n-type GaAs layer 7 above the mesa exposed as a result are contacted with a probe or the like, and the electrical resistance between the two terminals A and A ′ is measured. Since the resistivity of the layer is sufficiently low, the measured electric resistance is the resistance of the AlAs layer 2 in the mesa portion. As shown in FIG. 7, when the oxidation state is changed, X = L /
A hyperbolic change with 2 asymptote is shown, and the manner of change is R = R0 + ρd / 4 (XL / 2) 2. Here, R is the resistance value to be measured, and L is the cross section (square) of the mesa.
Ρ is the resistivity of the AlAs layer. Also,
R0 is a parasitic resistance such as a contact resistance, but is a small value and may be ignored. In order to avoid a variation in the resistance value due to a variation in the contact resistance between the probe and the n-type GaAs layer and perform a more strict evaluation, it is necessary to form the n-type GaAs after forming the side wall.
An electrode may be formed over the layer. The optimum value of the thickness d of the AlAs layer 2 varies depending on the doping concentration and the cross-sectional area of the mesa, but is suitably about 100 to 500 nm. If the thickness is too large, the change in resistance due to oxidation of the AlAs surface will be small, and the measurement accuracy will decrease. When a slight change in resistance is measured, L / d is preferably set to be large.
As described above, the correlation between the oxidation amount and the resistance value with respect to AlAs as shown in FIG. 7 is measured in advance, and the electrical resistance obtained for an arbitrary process is compared with FIG. Can be obtained. Thereafter, the amount of oxidation of the GaAs surface can be obtained by the same procedure as in the first embodiment.

In the process evaluation method of the third embodiment, unlike the first and second embodiments, the mesa of the AlAs layer is formed and oxidized, so that the same substrate is used to reduce the cross-sectional area. Different mesa structures can be created. For this reason, in the first and second embodiments, a decrease in the resistance measurement accuracy due to the fluctuation of the contact resistance between the electrode and the AlAs layer was unavoidable. In the present embodiment, the resistance of a plurality of mesas having different cross-sectional areas was inevitable. By measuring the value and normalizing it by the cross-sectional area, there is an effect that the contact resistance can be removed and the resistance can be measured.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described in detail. FIG. 8B is a plan view of a process evaluation pattern used in the fourth embodiment, and FIG.
Is a sectional view taken along line AA ′. In this fourth embodiment,
The difference from the third embodiment is that the cross section of the mesa is circular. Other mesa formation methods and evaluation methods are exactly the same as those of the third embodiment. In this embodiment, since the cross section of the mesa is circular, the measured electric resistance shows a hyperbolic change with X = r asymptote when the oxidation state is changed, and the way of change is R = R0 + ρd / π (X−r) 2. Here, R is the measured resistance value, r is the radius of the cross section of the mesa, and ρ is the resistivity of the AlAs layer. R0 is a parasitic resistance such as a contact resistance, but is a small value and may be ignored. As described above, in this embodiment, the resistance change with respect to the oxidation amount is smaller by 4 / π than in the third embodiment.
Therefore, it is suitable for measuring a slight oxidation amount.

(Embodiment 5) Next, a fifth embodiment of the present invention will be described in detail. FIG. 9D is a plan view of a process evaluation pattern used in the third embodiment, and FIG.
9C are cross-sectional views taken along line AA ′ in the order of steps, and FIG. 9E is a cross-sectional view taken along line BB ′. The fourth embodiment is different from the third and fourth embodiments in that the mesa is formed in a stripe shape. First, as shown in FIG. 9A, a stripe-shaped mesa is formed in the same manner as in the third and fourth embodiments. However, the crystal structure is different from those of the third and fourth embodiments, and n is directly formed on the semi-insulating GaAs substrate 1.
A type AlAs layer is grown, or a high-resistance non-doped GaAs is formed on a semi-insulating GaAs substrate as shown in FIG.
After growing the n-type AlAs layer 10, the n-type AlAs layer 2 is grown, and then the non-doped GaAs 11 with high resistance is grown. Next, as shown in FIG. 9B, an opening 12 is formed by cutting a mesa using a mask pattern such as a photoresist. Thereafter, as shown in FIG. 9C, electrodes 13 and 14 are formed to complete the evaluation pattern. It is convenient and appropriate to use a lift-off method for forming the electrodes. The electrodes 13 and 14 formed in this way are exposed to Al exposed on the side surfaces of the mesa.
A so-called lateral contact is made in lateral contact with the As layer, but a current flows between the electrodes until the AlAs layer is completely oxidized to Al2O3 which is an insulator.

A plurality of such stripe-shaped mesas are prepared by changing the width of the stripe, and the conduction between the electrodes is measured, whereby the oxidation amount can be measured more precisely. That is, when there is conduction in the pattern with the stripe width A and there is no conduction in the pattern with the width B, the oxidation amount X becomes
The relationship of A>2X> B is satisfied. For this reason, if you create a large number of patterns with slightly different stripe widths,
The oxidation amount X can be measured exactly. After measuring the oxidation amount of the AlAs layer as described above, the oxidation amount of the GaAs surface can be obtained by the same procedure as in the first embodiment. This embodiment is different from the first to fourth embodiments in that the measurement of the amount of oxidation is performed not by a resistance change but by the presence or absence of conduction. Therefore, there is an effect that a decrease in measurement accuracy due to a change in contact resistance or the like can be avoided.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like that do not depart from the gist of the present invention. Is also included in the present invention. For example, in the above-described first embodiment, in order to obtain the oxidation amount of the GaAs layer, the oxidation amount of the AlAs layer was obtained by measuring the resistance. However, the present invention is not limited to this. , The same effect can be obtained. Also, the oxidation amount of the InGaAs layer can be obtained from the oxidation amount of the AlAs layer.
In addition, the same effect can be obtained by using another material such as phosphorus or antimony as the group V element. Further, in the embodiment, as a manufacturing process to be evaluated, Si0
2 The formation of the protective film has been described, but not limited thereto.
Similarly, any process that oxidizes the semiconductor surface, such as a film forming process, a thermal oxidation process, a plasma process, or a wet process, can easily and accurately determine the amount of oxidation.

[0023]

As described above, according to the first and fourth aspects of the present invention, in order to measure the amount of oxidation of a compound semiconductor in a manufacturing process of a compound semiconductor device,
A material with a higher oxidation rate than a semiconductor material is subjected to a process under the same conditions as the manufacturing process for which the amount of oxidation is to be measured, and the electrical resistance change of the material with a higher oxidation rate is measured. Compared with the method using high-power microscope observation, the amount of oxidation of the compound semiconductor can be measured simply and with high accuracy.

According to the second, third, and fourth aspects of the present invention, in order to measure the amount of oxidation of the compound semiconductor material in the manufacturing process of the compound semiconductor device, a stack including a material having a higher oxidation rate than the semiconductor material is used. It is composed of a structure,
By using a mesa pattern in which a material having a high oxidation rate is exposed on the side surface, a manufacturing process including a process under the same conditions as a manufacturing process whose oxidation amount is to be measured is performed.
Since the electrical resistance change of a mesa pattern containing a material having a high oxidation rate is measured, in addition to the effect obtained by the configuration according to claim 1, the resistance values of a plurality of mesas having different cross-sectional areas are measured and normalized by the cross-sectional area. be able to. Therefore, the contact resistance can be removed and the resistance can be measured more strictly, so that the oxidation amount of the compound semiconductor can be measured with higher accuracy.

According to a fifth aspect of the present invention, in the configuration of the second, third, or fourth aspect, the laminated structure includes a material having a higher oxidation rate than the semiconductor material. With a mesa-type structure such as exposed to the process evaluation pattern composed of a plurality of stripe-shaped patterns having different widths, by measuring the presence or absence of conduction in a plurality of patterns, The amount of oxidation of the compound semiconductor can be easily measured.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a structure of an evaluation pattern used in a process evaluation method according to a first embodiment of the present invention, wherein FIG. 1C is a cross-sectional view, and FIGS. (D) is a plan view.

FIG. 2 is a diagram showing a relationship between an oxidation amount X and an electric resistance R of an evaluation pattern used in a process evaluation method according to a first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between an oxidation time and an oxidation amount X for GaAs and AlAs.

FIGS. 4A and 4B are diagrams showing a structure of an evaluation pattern used in a process evaluation method according to a second embodiment of the present invention, wherein FIG. 4A is a cross-sectional view and FIG.

5A and 5B are diagrams showing a structure of an evaluation pattern used in a process evaluation method according to a third embodiment of the present invention, wherein FIG. 5D is a cross-sectional view, and FIGS. FIG. 4E is a sectional view in the order of processes during manufacturing, and FIG.

FIG. 6 is a diagram showing a method of measuring resistance in a process evaluation method according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between an oxidation amount X and an electric resistance R of an evaluation pattern used in a process evaluation method according to a third embodiment of the present invention.

8A and 8B are diagrams showing a structure of an evaluation pattern used in a process evaluation method according to a fourth embodiment of the present invention, wherein FIG. 8A is a sectional view and FIG. 8B is a plan view.

FIG. 9 is a view showing a structure of an evaluation pattern used in a process evaluation method according to a fifth embodiment of the present invention, wherein (d) is a cross-sectional view, and (a), (b) and (c) are evaluation patterns. FIG. 4E is a sectional view in the order of processes during manufacturing, and FIG.

10A and 10B are diagrams showing a semiconductor chip structure of a conventional MESFET, where FIG. 10A is a cross-sectional view and FIG. 10B is a plan view.

FIG. 11 is a diagram showing the relationship between the amount of surface oxidation at the protective film interface and the breakdown voltage of a conventional MESFET.

[Explanation of symbols]

 Reference Signs List 1 semi-insulating GaAs substrate 2 n-type GaAs layer 3 SiO2 protective film 4 oxide layer 5 electrode 6 electrode 7 n-type GaAs waist 8 n-type GaAs layer 9 sidewall 10 non-doped GaAs layer 11 non-doped GaAs layer 12 opening 13 electrode 14 electrode 15 n-type GaAs active layer 16 n-type GaAs ohmic contact layer 17 gate electrode 18 drain electrode 19 source electrode 20 protective film

Claims (5)

[Claims] 1. A method for evaluating a manufacturing process of a compound semiconductor device, wherein a manufacturing process under the same conditions as the manufacturing process is performed on a material having an oxidation rate higher than that of the compound semiconductor material, and the manufacturing process is terminated. A method for evaluating a manufacturing process of a compound semiconductor device, comprising: measuring a change in electric resistance of the material having a high oxidation rate. 2. A method for evaluating a manufacturing process of a compound semiconductor device, comprising the steps of: epitaxially growing a laminated structure containing a material having a higher oxidation rate than the compound semiconductor material; and exposing the material having a higher oxidation rate to a side surface by etching. A method of manufacturing a compound semiconductor device, the method comprising: measuring a change in electric resistance of a mesapatan containing a material having a high oxidation rate after the completion of the manufacturing process. 3. A method for evaluating a manufacturing process of a compound semiconductor device, comprising the steps of: epitaxially growing a laminated structure including a material having a higher oxidation rate than the semiconductor material; and exposing the material having a higher oxidation rate to a side surface by etching. A step of manufacturing such a mesapattern, and a manufacturing process including a step of forming a protective film under the same conditions as the manufacturing process are completed, and measuring a change in electrical resistance of the mesapatan including the material having a high oxidation rate. A method for evaluating a manufacturing process of a compound semiconductor device. 4. The compound III element of the compound semiconductor material is Ga
4. The method according to claim 1, wherein the substance having a high oxidation rate is a compound semiconductor material using Al as a group III element. 5. A process evaluation pattern used for evaluating a manufacturing process of a compound semiconductor device, wherein the stack includes a material having an oxidation rate higher than that of the semiconductor material in order to measure an oxidation amount of the compound semiconductor material in the manufacturing process. A process evaluation pattern comprising a plurality of stripe-shaped patterns having a mesa structure in which the material having a high oxidation rate is exposed on a side surface thereof and having different widths.