JPH0758131A - Method for manufacturing field effect transistor and integrated circuit thereof - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] High output and high efficiency of multiple types of MESFE
Provided is a manufacturing method for efficiently producing T. [Structure] Channel layer 8 formed on the surface of semiconductor substrate 1
A plurality of resist patterns 11 are formed on the upper side at a predetermined interval and are reduced by etching to eliminate the portion 11 on the side to be the drain region C. Therefore, the portion 11 on the side to be the reduced and left source region A is removed. The distance between the gate electrode 3 and the A-side low resistance region formed in the inversion trace is short, and the distance between the electrode 3 and the C-side is long, so that an asymmetric structure can be realized.
Also, when implanting ions into the A and C regions from two directions,
Since the implantation of impurity ions is partially blocked from 11
A low-concentration region and a high-concentration region can be formed symmetrically with respect to the A and C directions in the low-resistance regions formed respectively.
It becomes a structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a field effect transistor (FET), and more particularly to a field effect transistor having high output and high gain suitable for integration and a method for manufacturing the integrated circuit. It is a thing.

[0002]

2. Description of the Related Art In recent years, with the rapid progress of information network systems, semiconductor devices have also been required to realize characteristics such as ultra-high speed operation, high frequency operation, low power consumption and high efficiency. Since a shot barrier type FET (MESFET) made of is expected to have characteristics that meet the above requirements, application research for ultra-high speed, high frequency circuits and the like is being actively conducted.

To increase the output and efficiency of the GaAs MESFET, specifically, the resistance between the source electrode and the gate electrode, that is, the source resistance Rs is reduced to improve the mutual conductance (g _m ). At the same time, it is important to increase the drain breakdown voltage between the drain electrode and the gate electrode.

On the other hand, as a method for improving the manufacturing yield of this GaAs MESFET, there is a technique disclosed in, for example, Japanese Patent Application Laid-Open No. 58-60574 shown in FIG. 3 (first conventional example). According to the conventional example of substrate 1,
Low-resistance region 2 with high-concentration ion implantation of impurities on the surface
a and 2b are formed in self alignment with the gate electrode 3, and a source electrode 4 and a drain electrode 5 are formed on the low resistance regions 2a and 2b.

However, in the first conventional example, the distance L _SG between the source side low resistance region 2a and the gate electrode 3 and the distance L _DG between the drain side low resistance region 2b and the gate electrode 3 are equal, If the distance L _SG is reduced in order to reduce the source resistance Rs, L _DG is also reduced and the drain breakdown voltage is reduced. On the contrary, if the distance L _DG is increased to improve the drain breakdown voltage, L _SG also increases, the source resistance Rs increases, and the mutual conductance g _m decreases.

Therefore, as a method for solving the above problems, for example, Japanese Patent Application Laid-Open No. 58-223372 (second prior art), Japanese Patent Application Laid-Open No. 4-264737 (third prior art), etc. A structure is disclosed in which the gate electrode is formed asymmetrically so that the above distance is L _DG > L _SG .

That is, in the second conventional example, after forming a mask pattern for blocking, impurity ions are implanted from a direction inclined to the source side (ion implantation into the region blocked by the photoresist). However, the low resistance regions on the source and drain sides and the gate electrode are asymmetrical.

On the other hand, in the third conventional example, a resist pattern for limiting the ion implantation region is formed symmetrically, the source side is covered with a photoresist, and only the resist pattern on the drain side (for limiting the ion implantation region) is etched. After that, an asymmetric structure is realized by ion implantation.

Further, for example, Japanese Patent Laid-Open No. 61-163666 (fourth prior art) discloses an LDD (Lightly Dope) as an MESFET capable of driving a large current and a load at high speed.
d Drain) technology for obtaining the structure is disclosed in FIG.
As shown in FIG. 4A, a mask pattern 7 having a specific shape is formed on the impurity introduction layers 6a and 6b provided on the semiconductor substrate 1, and as shown in FIG. After the impurity ions are implanted to form the low resistance region, ion implantation is further performed from both the source side and the drain side as shown in FIG. 4C to perform the implantation with a low concentration between each low resistance region and the gate electrode. LDD by forming layers
The structure is realized.

[0010]

As described above, the conventional method for manufacturing a field effect transistor uses the technique for realizing an asymmetric structure by implanting ions from an oblique direction as in the first conventional example, and using the MESFET. When manufacturing an array, the positional relationship between the source, gate, and drain electrodes is fixed when the direction of implanting the impurity ions is determined. Therefore, the electrodes are arranged in order as shown in FIG. A typical MESFET array (see FIG. 5).
Since the source electrode and the drain electrode cannot be shared as in (b), there is a problem that the area efficiency of the MESFET array chip is reduced (the wiring is omitted in FIG. 5). The source electrode, the gate electrode, and the drain electrode are connected by wiring).

Further, according to the third conventional example, in order to realize an asymmetric structure in the manufacturing process, a separate step of covering the source electrode side with photoresist and etching the drain electrode side is required. There is a problem that the cost is high and the manufacturing efficiency cannot be improved, and therefore the manufacturing yield cannot be improved.

Further, according to the fourth conventional example, in order to manufacture an MESFET having an LDD structure, a step of forming a low resistance layer in a source region and a drain region, and a concentration between the low resistance layer and the gate electrode Since a separate step of forming the low ion-implanted layer by performing ion implantation from two oblique directions is required, the manufacturing cost is increased and the manufacturing efficiency can be improved as in the third conventional example described above. Therefore, there is a problem that the manufacturing yield cannot be improved.

The present invention has been made to solve the above problems, and provides a method of manufacturing a field effect transistor and an integrated circuit thereof for efficiently producing a plurality of types of MESFETs with high output and high efficiency. The purpose is to provide.

[0014]

According to a method of manufacturing a field effect transistor according to the present invention, a resist pattern consisting of a resist single layer having a thickness a on a channel layer formed on a surface of a semiconductor substrate and having different pattern widths ( each pattern width L _1, L ₂ is a L _1> L _2, the pattern width of the side serving as the drain region and L ₂₎ to form at least two apart by a distance b (the first step) The angle at which impurity ions are not implanted into the semiconductor substrate between the resist patterns in regions other than the source region and the drain region using the resist pattern as a mask (that is, an angle θ that satisfies tan θ ≧ b / a with respect to the substrate normal line). ), And the impurity ions having the same conductivity type as the channel layer are inclined from the direction inclined toward the source region side and the direction inclined toward the drain region side, respectively. Injecting (second step), and further reducing the resist pattern by etching, as a result, the resist pattern on the side to be the drain region (the resist pattern having the smaller pattern width) of the two resist patterns disappeared. After that, an insulating film is deposited and pattern inversion is performed (third step) to form a source electrode and a drain electrode on the pattern inversion region, and a gate is left on the inversion trace of the resist pattern left on the side to be the source region. It is characterized in that an MESFET having an asymmetric structure is manufactured by forming electrodes (fourth step).

Further, in the above-mentioned first step, by forming only one resist pattern to be formed on the channel layer formed on the surface of the semiconductor substrate and performing ion implantation from the oblique direction twice as described above, It is also possible to manufacture a MESFET having an LDD structure (symmetrical with respect to the source / drain direction) having low-concentration regions between the low-resistance regions on the source side and the drain side and the gate electrode.

Further, the integrated circuit according to the present invention is manufactured by integrating the MESFETs manufactured by the above-described method in any combination.

[0017]

In the method of manufacturing a field effect transistor according to the present invention, in the first step, a plurality of resist patterns are formed at predetermined intervals and at arbitrary positions on the channel layer formed on the surface of the semiconductor substrate. At this time, the pattern width of the resist pattern formed on the side to be the drain region is made small), and in the third step, since the resist pattern is reduced by etching, the resist pattern on the side to be the drain region disappears, The distance between the gate electrode and the source-side low-resistance region formed on the inversion trace of the resist pattern left on the side to be the source region is short, and the distance between the gate electrode and the drain-side low-resistance region is long. So it is possible to realize any asymmetric structure.

In the second step, when ions are implanted into the source and drain regions from two directions,
Since the implantation of the impurity ions is partially blocked by the resist pattern, a low-concentration region and a high-concentration region (LDD structure) are formed in the source / drain direction in the low resistance regions formed on the source side and the drain side, respectively. It is formed symmetrically.

By sharing the steps of manufacturing a plurality of types of MESFETs as described above, the manufacturing efficiency when integrated on the same substrate is improved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In the figure, the same parts are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a diagram for explaining a method for manufacturing a field effect transistor according to the present invention, and the manufacturing method will be described below for each step.

In the first step, first, a resist 9 having a thickness a is patterned on the main surface of a GaAs substrate 1 which is a semi-insulating compound semiconductor, and further, an acceleration voltage of 40 kev and a dose amount of 8 are applied to the GaAs substrate 1. Under the condition of × 10 ¹² cm ^-2 , ions of Si, Se, etc., which become n-type impurities, are ion-implanted to form the channel layer 8 of the GaAs MESFET (FIG. 1A).

Next, the resist 9 is removed, and the SiN film 10 as a surface protective film is deposited on the GaAs substrate 1 by 800Å by ECR plasma CVD, plasma CVD method or the like. Then, a resist pattern 11 having a thickness a (= 2.2 μm) is applied to the entire surface of the GaAs substrate 1, exposed and developed, and the source region A and the drain region C (however, these regions may be reversed). ) And the gate region B is removed.
And the pattern width is L ₁ = 1.1 μm, L ₂ = 0.4 μm
The two resist patterns 11 are formed so as to cross the channel layer 8 by a distance b (= 0.6 μm) (FIG. 1B).

Subsequently, in the second step, the GaAs
Facing the substrate 1, n-type impurity (Si, Se, etc.) ions are accelerated at a voltage of 90 keV from each of a direction inclined by θ = 17 ° toward the source region A side and a direction inclined by θ = 17 ° toward the drain region C side. Ion implantation is performed twice in the GaAs substrate 1 under the condition of a dose amount of 3 × 10 ¹³ cm ⁻² . At this time,
A low resistance ion-implanted layer (low resistance region 12a) is formed in the region that has been ion-implanted both times.
The region 12b which is shaded by 1 and which is injected only once becomes a lightly doped layer having a low concentration (FIG. 1).
(C)).

The angle of ion implantation is tan θ =
0.305 (θ is the angle taken with respect to the normal to the substrate surface) and b / a = 0.273, so tan θ
> B / a, the resist pattern 11 serves as a wall, and the n-type impurity is not ion-implanted into the GaAs substrate 1 between the two resist patterns 11 in FIG. 1C. Further, the acceleration energy and the dose amount of the two times of ion implantation are set to the same condition in this embodiment.
When it is not necessary to create the MESFET array as shown in (b), the same conditions are not always satisfied.

As described above, the low resistance regions 12a and 12b are formed in the GaAs substrate 1 on the source side and the drain side, respectively.
After the formation of (symmetrical with respect to the source / drain direction), isotropic etching is performed by RIE (Reactive Ion Etching) using oxygen ions in each of the third steps. The surface of is etched by 0.2 μm to be reduced.

Therefore, after this etching step, the thickness a of each resist pattern 11 is 2.0 μm, and the pattern width is L1 = 0.7 μm and L2 = 0 μm (see FIG. 1).
(D)), the resist pattern 11 on the drain region C side disappears.

Subsequently, SiO ₂ 13 which is an insulating film is formed on the surface of the GaAs substrate 1 which has undergone the above steps by sputtering.
Of SiO ₂ 13 accumulated on the surface of the remaining resist pattern 11 on the side of the source region A after the deposition of 3000 Å
Are removed with a dilute aqueous solution of hydrofluoric acid, and the resist pattern 11 is lifted off using an organic solvent to perform pattern inversion (FIG. 1E).

Finally, in the fourth step, in order to activate the ion-implanted n-type impurity ions, 800
Annealing is performed at 20 ° C. for 20 minutes to form an ohmic pattern with a resist to form a source region A and a drain region C.
The SiO ₂ 13 and the SiN film 10 are removed by RIE using CF ₄ and H ₂ , and ohmic metal formation and alloying are performed as the source electrode 4 and the drain electrode 5.

Similarly, the gate pattern is formed on the SiO ₂ pattern on the source side by the resist (inversion trace of the resist pattern 11 between the source electrode 4 and the drain electrode 5).
Then, the gate electrode 3 is formed by removing the SiN film 10 (FIG. 1F).

In this embodiment, the distance (L _SG ) between the low resistance region on the source electrode side and the gate electrode is 0.2 μm, and the distance (L _DG ) between the low resistance region on the drain electrode side and the gate electrode. Is 0.5 μm, and an asymmetric structure MESFET (having an LDD structure symmetrical with respect to the source / drain direction) with L _DG > L _SG can be produced in a self-aligned manner. Further, since the positional relationship between the source electrode and the drain electrode can be arbitrarily changed depending on the position where the gate electrode is formed, each electrode can be shared during integration, so that even when manufacturing the MESFET array. The area efficiency above does not decrease.

Here, the L _DG is the resist pattern 11
The width can be easily changed to a desired length by changing the widths L ₁ and L ₂ , the distance b and the ion implantation angle θ, which is not particularly specified in this embodiment.

Further, as shown in FIG. 2, in the step of forming the low resistance regions 12a and 12b in a self-aligned manner by ion implantation, one resist pattern is used as shown in FIG. By performing oblique ion implantation from the respective directions of the source side and the drain side, as shown in FIG.
It is possible to realize a MESFET having a DD structure.

Further, the above-mentioned asymmetric MESFET, L
Each of the MESFETs having the DD structure can be easily integrated at the same time by sharing each manufacturing process and without increasing the number of processes, and an integrated circuit (IC) according to the invention according to claim 2 is realized. can do.

Although the channel layer 8 of the MESFET is formed by the ion implantation method in this embodiment, the method is not particularly limited to this method and the MBE method, CBE method,
An epitaxial crystal layer grown by a crystal growth method such as OMVPE (MOCVD) method or chloride VPE method may be used.

Other compound semiconductor substrates (for example, In
The ion implantation layer for P) and the epitaxial layer grown on the substrate may be used as the channel layer.

[0037]

As described above, in the method of manufacturing a field effect transistor according to the present invention, in the first step, a plurality of resist patterns are formed at predetermined intervals on the channel layer formed on the surface of the semiconductor substrate. The resist pattern is formed at an arbitrary position, and in the third step, the resist pattern on the side to be the drain region is reduced by etching to reduce the resist pattern. Therefore, the reduced resist pattern on the side to be the source region is left. The distance between the gate electrode and the source-side low-resistance region formed in the inversion trace is short, and the distance between the gate electrode and the drain-side low-resistance region is long, so that an arbitrary asymmetric structure can be realized.

Since an LDD structure symmetrical with respect to the source / drain direction can be formed in each source region and drain region, and the positional relationship of each electrode can be set arbitrarily, when manufacturing a MESFET array. The electrodes can be shared, and the area efficiency of the array chip is not reduced.

In the second step, when ions are implanted into the source and drain regions from two directions,
Since the implantation of impurity ions is partially blocked by the resist pattern, the low-concentration region and the high-concentration region are symmetrical in the source / drain direction in the low resistance regions formed on the source side and the drain side, respectively. MESF that can be formed and has an LDD structure without increasing the manufacturing process.
There is an effect that ET can be manufactured.

Further, as described above, a plurality of types of MESF
By sharing the process of manufacturing the ET, there is an effect that the manufacturing efficiency when integrated on the same substrate can be improved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining each step of manufacturing an asymmetric MESFET by a method of manufacturing a field effect transistor according to the present invention.

FIG. 2 is a diagram for explaining each step of manufacturing a MESFET having an LDD structure by the method for manufacturing a field effect transistor according to the present invention.

FIG. 3 is a diagram showing a structure of a field effect transistor according to a first conventional example.

FIG. 4 is a diagram showing a manufacturing process of a field effect transistor according to a fourth conventional example.

FIG. 5 is a diagram showing electrode arrangement patterns of a second conventional example and a third conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate (GaAs), 3 ... Gate electrode 4 ... Source electrode, 5 ... Drain electrode, 8 ... Channel layer, 11 ... Resist pattern, 12a, 12b ... Low resistance area | region.

Claims (2)

[Claims] 1. A step of forming a resist pattern composed of at least two resist single layers on an active layer formed on a surface of a semiconductor substrate, wherein a pattern width of the resist pattern on a side to be a drain region is set. A first step of forming small, using the resist pattern as a mask, in an area other than the source region and the drain region, at an angle at which impurity ions are not implanted into the semiconductor substrate between the resist patterns, and the same as the active layer A second step of implanting conductivity type impurity ions from a direction inclined to the source region side and a direction inclined to the drain region side, and the resist pattern is reduced by etching to form a resist pattern of the resist pattern. After erasing the resist pattern on the side that will be the drain region, deposit an insulating film and reverse the pattern. And a fourth step of forming a source electrode and a drain electrode on the pattern inversion region, and then forming a gate electrode on the inversion trace of the resist pattern left on the side to be the source region. Method for manufacturing a field effect transistor. 2. An integrated circuit in which various field effect transistors including the field effect transistor manufactured by the manufacturing method according to claim 1 are arbitrarily combined and integrated.