KR100248415B1 - Fabrication method of monolithic microwave integrated circuit - Google Patents

Abstract

A method of fabricating a single chip microwave integrated circuit (MMIC) on a compound semiconductor epitaxial substrate is disclosed. The present invention provides a buffer layer and an active layer for the fabrication of passive devices on a semi-insulating substrate, and epitaxial growth of the first metal layer, the dielectric layer and the second metal layer for the fabrication of active devices. Continuously growing in the same chamber, etching the second metal layer, etching the dielectric layer, defining the active device channel layer, source and drain deposition of the active device, recess etching for the gate deposition, and A gate forming step is provided to greatly simplify the manufacturing process of the MMIC.

Description

Manufacturing method of single chip microwave integrated circuit

In forming the substrate structure of MMIC (Monolithic Microwave Integrated Circuit) by the epitaxial growth method, after manufacturing the epitaxial substrate of the active device structure required by the MMIC, the metal layer and the dielectric layer required to manufacture the MMIC passive device continuously Form an improved MMIC that can simplify the manufacturing process.

The present invention relates to a method for fabricating an MMIC using a compound semiconductor epitaxial substrate, and more particularly, to a method for manufacturing an MMIC by growing the structure of the substrate to a material required for the MMIC when fabricating the MMIC using an epitaxial substrate. .

Monolithic microwave integrated circuits (hereinafter, referred to as MMICs) can be fabricated in a batch process to connect active and passive devices as well as unit devices on a semiconductor substrate. Therefore, compared with the conventional high frequency circuit board, the size, high reliability, and uniformity of the advantages of the advantage that the manufacturing cost compared to the case of manufacturing a high frequency circuit using individual components. As a result, the market competitiveness of the wireless communication device can be enhanced.

In addition, high-frequency circuit boards use only components packaged in a specific form, so there is little freedom in component selection, while in MMIC, circuit designers can adjust the size of the element in any form, optimizing performance according to the purpose. Increasing the number of devices does not affect the manufacturing cost, and one of the advantages is that circuits of various structures are possible.

Conventionally, by forming an active layer by ion implantation, and then repeatedly etching and depositing to manufacture the MMIC through about 150 process steps, the process is complicated and the reproducibility is low, the production cost is high and the yield is low. There was this.

The epitaxial substrate used in the present invention has a relatively high production cost and lower throughput than the substrate manufactured by the ion implantation method, so that there are many limitation factors for mass production, while the high frequency circuit elements are multiplied in small quantities and epitaxial growth methods. Improvements have also been made to the technology to meet production costs. Therefore, MMIC production by epitaxial substrate is expected to be made in the future.

In the present invention, by manufacturing the MMIC by the epitaxial substrate, the MMIC capable of manufacturing active and passive devices by a continuous process by continuously growing on the spot after fabricating the epitaxial substrate and depositing the metal to be prepared again. Disclosed is a manufacturing method of.

According to the present invention, a channel layer, two metal layers, and a dielectric layer required in an MMIC structure are sequentially grown in epitaxy equipment to fabricate an epitaxial substrate, and then a process step is minimized by manufacturing a passive element and an active element on the substrate. will be.

1 is a cross-sectional view schematically showing an epitaxial substrate structure for manufacturing a microwave integrated circuit according to the present invention;

2 (a) to 2 (f) are cross-sectional views sequentially illustrating a manufacturing process of the microwave integrated circuit according to the embodiment of the present invention.

* Explanation of symbols on the main parts of the drawings

One ; Compound semiconductor semi-insulating substrate 2; Compound Semiconductor Buffer Layer

3; Compound semiconductor channel layer 4; First metal layer

5; Dielectric layer 6; Second metal layer

8 ; Source 9; drain

11; gate

MMIC manufacturing method of the present invention for achieving the above object,

A buffer layer and an active layer for fabricating passive devices on a semi-insulating substrate, and a first metal layer, a dielectric layer, and a second metal layer for fabricating an active device are epitaxially grown in the same chamber. Successive growth of the second metal layer to remove a portion of the second metal layer using a mask for defining an active region of the active device, and removing the dielectric layer using the same mask. Etching the dielectric layer, defining a channel layer of an active device which performs the etching for isolation of the channel layer after removing the first metal layer, and forming a source / drain of the probable element on the channel layer. And a recess etching step of the channel layer for gate deposition of the device, and a gate deposition step.

Preferably, the dielectric layer for fabricating the active device is made of aluminum arsenide (AlAs) to be formed through a continuous process in the same epitaxial growth equipment.

More preferably, the first and second metal layers for manufacturing the active element for the MMIC are made of the same metal, and can be formed in epitaxial growth equipment to improve crystallinity with the epitaxial layer for the passive element. Gallium, and aluminum, characterized in that the use of a metal.

According to a preferred embodiment of the present invention, by continuously manufacturing the MMIC in the same epitaxial growth equipment, the oxide film is prevented from occurring at the interface between the epitaxial substrate and the metal in advance, and the crystal metal is matched with the lattice according to the epitaxial method. By fabricating even, it is possible to simplify the process while improving the reproducibility of the device process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing the structure of an epitaxial substrate for a single-chip MMIC used in the present invention. Reference numeral 1 denotes an undoped semi-insulating substrate having a high resistance of ˜10 ⁷ ohm.cm or more, and typically refers to gallium arsenide. use. An epitaxial layer is formed on the semi-insulating substrate 1 for manufacturing an active device.

Specifically, the epitaxial layer serves to prevent defects on the substrate 1 from being transferred to the epitaxial layer upon growth, and has a thickness of about 1 micrometer for the purpose of obtaining a higher resistance than the substrate. A buffer layer 2 and then an active layer 3 capable of forming a channel. In addition, although not shown in the drawings, a cap layer doped with ~ 10 ¹⁷ impurities per unit centimeter volume may be further provided on the active layer 3. This cap layer serves to improve the ohmic contact properties by doping at least 10 ¹⁸ impurities per unit centimeter in joining a metal and a semiconductor required for fabricating an active device.

Subsequently, layers for fabricating passive elements of the MMIC are continuously grown.

In FIG. 1, reference numeral 4 denotes a first metal layer for fabricating a passive element of the MMIC, using aluminum, indium, gallium, or the like, which is a metal in the epitaxial growth equipment, on the active layer 3 for the active element. Growing continuously.

Accordingly, since the first metal layer 4 is not exposed to the air, not only impurities are present at the interface, but also the crystallinity of several angstroms can be maintained between the semiconductor material of the active layer 3 and the metal. Therefore, the film quality of the metal becomes electrically excellent.

The dielectric layer 5 grown on the first metal layer 4 is a dielectric for fabricating a capacitor, which is a passive element. Generally, silicon nitride, tantalum oxide, or the like is used, and sputtering and vacuum evaporation are performed. And vapor phase chemical vapor deposition (CVD) methods, but in the present invention, epitaxial growth is performed using aluminum arsenide (AlAs) for the continuous process. On the dielectric layer 5, a second metal layer 6 is formed of the same metal as the first metal layer 4 in the same equipment.

In this structure, a capacitor, which is one of the passive elements of the MMIC, is implemented by the first metal layer 4, the dielectric layer 5, and the second metal layer 6. That is, the area of the metal plate to obtain the capacitance of the desired capacity is defined and the remaining portion is removed by etching. Hanfun, inductors and resistors are also fabricated using the second metal layer 6 and the first metal layer 4.

Next, a method of manufacturing an MMIC using an epitaxial substrate having the above-described configuration will be described with reference to FIGS. 2A to 2F.

2A schematically illustrates an etching step of the second metal layer 6, FIG. 2B illustrates an etching step of the dielectric layer 5, and FIG. 2C defines an active element channel layer 3a. 2 (d) shows a step of depositing the source and drain (8, 9) of the active device, FIG. 2 (e) shows the etching of the recess 10 for the gate deposition, and FIG. 2 (f) shows the gate Each of the steps of forming (11) is shown.

Specifically, in the etching step of the second metal layer 6, which is the first step, wet etching using hydrochloric acid is used as the etching solution because aluminum is usually used.

In the etching step of the dielectric layer 5, which is the second step, as shown in Fig. 2 (b), because aluminum arsenide is used as the dielectric, it is also performed by wet etching with hydrochloric acid.

In the third step of defining a channel, first, the first metal layer 4 is removed by wet etching, and then etching is performed for isolation of the channel layer, as shown in FIG. The channel region 3a for production is defined.

In the fourth step of depositing the source 8 and the drain 9, gold-germanium is deposited as the source / drain metal and completed.

In the fifth gate recess etching step as shown in Fig. 2 (e), the current of the source and the drain is monitored and a portion of the active layer of the region where the gate is to be formed is removed using sulfuric acid, hydrogen peroxide and deionized water. It is a recess etch.

Finally, in the sixth step, the gate metal deposition step, titanium / platinum / gold is deposited to complete the gate 11, as shown in FIG. 2 (f).

Such a six-step MMIC manufacturing method can be completed in about 50 or less process steps. Thus, the present invention can significantly reduce the number of processes compared to the conventional method comprising about 150 process steps by repeating the ion implantation method and deposition and etching.

This invention can be implemented in other various forms, without deviating from the mind or main character. For this reason, the above-described embodiments are merely examples in all respects and should not be interpreted limitedly.

As described above, according to the manufacturing method of the MMIC according to the present invention, the epitaxial substrate is grown into the MMIC structure and the MMIC is manufactured by the six-step process method, thereby reducing the conventional process step by 1/3. As a result, the production cost of the chip can be lowered and the process steps are shorter, so that the yield is improved and the reproducibility of the device process can be increased.

Furthermore, by continuously fabricating the epitaxial substrate structure for fabricating active and passive devices, it is possible to prevent the formation of oxide films at the interface between the epitaxial substrate and the metal, and to match the lattice according to the epitaxial method and even the crystal metal. By manufacturing continuously, the electrical properties of the metal can be improved.

Claims (3)

A buffer layer and an active layer for fabricating passive devices on a semi-insulating substrate, and a first metal layer, a dielectric layer, and a second metal layer for fabricating an active device are epitaxially grown in the same chamber. Continuously growing in the; Etching the second metal layer to remove a portion of the second metal layer by using a mask for defining an active region of the active device; Etching the dielectric layer to remove the dielectric layer using the same mask; Defining a channel layer of an active device which removes the first metal layer and then performs etching for isolation of the channel layer; Forming a source / drain of the competent element on the channel layer; Recess etching of the channel layer for gate deposition of an active element; And A method for fabricating a single chip microwave integrated circuit comprising a gate deposition step. The method of claim 1, The dielectric layer for manufacturing the active device, A method for fabricating a single chip microwave integrated circuit comprising aluminum arsenide (AsAl) to be formed through a continuous process in the same epitaxial growth equipment. The method of claim 1, First and second metal layers for manufacturing the active element for the MMIC, A method of manufacturing an MMIC, comprising: a metal made of the same metal and made of any one of indium, gallium, and aluminum, which can be formed in an epitaxial growth device to improve crystallinity with the epitaxial layer for the passive device. .

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