TW200416899A - Manufacturing method for sub-micrometer T-shaped double time gate etchings - Google Patents

Abstract

The present invention is related to the manufacturing method for sub-micrometer T-shaped double time gate etchings. A new four-layer positive photoresist (PR) assembling manner is proposed; and by using single positioning exposure through the application of electron beam photolithography system, T-shaped gate can be formed such that the problem of having over-high resistance for the gate of sub-micrometer field effect transistor can be solved. By using gate etching twice, the breakdown voltage and lifetime of integrated circuit are increased, and the device manufacture yield is increased. In the invented method, only one time of positioning and electron beam exposure is required; and I-shaped opening with sub-micrometer line-width can be formed for conducting two times of gate etching after tow times of developing process through the use of developer. As compared with the conventional technique, the present invention has higher efficiency, progress characteristic and industrial utilization value.

Description

200416899

V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a method of submicron to τ4, and in particular to a method of making a sub-beam lithography system using a new type of double-gate etching. The single-position electron four-layer positive photoresistor combination is used to perform double gate etching, beam exposure using electric development, and a double method of developing solution. Forming sub-micron τ-type gates [Previous technology] It is known that the current GaAs high-speed field-effect transistor for microwave wireless communication currently plays a role in the breakdown voltage and lifetime of the high-power breakdown voltage-accumulator circuit. Important position 'In order to make the adding technology a very important process step, the double gate etching of the active element is known. The double-phase electrode technology of the known method requires two separate, development, and etching to achieve double closed-pole etching. . After the first positioning exposure, development, and etching, the second time is used to make the second micron τ-type gate using electron beam lithography technology and three-layer photoresist. This technology for manufacturing T-gates uses three layers of polymethylmethacrylate, polymethylmethacrylate / methacrylic acid, and polymethylmethacrylate (P with A, P (MMA / MAA), PMMA). The photoresist is obtained by electron beam exposure. During the exposure process, first use a smaller line width and a higher energy electron beam to expose the lower part of the photoresist at the bottom; then use a larger line: a lower energy electron beam to expose the upper layer. And the middle layer of photoresist was exposed by the cutter of the exposure department. After the development, the metal is mined again to obtain the submicron T-gate. Please refer to Figures ia to ii for a description of such parties. Please refer to FIG. 1a, firstly, the first epitaxial layer 12 and the second epitaxial layer 1 4 are grown on the gallium arsenide or phosphorus 200416899 V. Description of the Invention (2) Indium substrate 10; The telephoto layer 14 is covered with a photoresist 16 (that is, polymethylmethacrylate / methacrylic acid (P (MMA / MAA))) for the first positioning exposure. Then the photoresist 16 is removed with a developing solution. Photosensitive part; see picture 1b 'after the rest; see picture 1c, and then remove the photoresist 16 with acetone, see picture 1d, and then cover the first Layer photoresist 20 (ie polymethyl methacrylate (PMM A)) and second layer photoresist 2 2 (ie polymethyl methacrylate / methacrylic acid (P (MMA / MAA))), and then Cover the third layer of photoresist 24 (that is, polymethyl methacrylate (PMMA)), as shown in Figure 1e, respectively, with different energy electron beams for exposure, and two different photoresist areas between different photoresists. , And then with = photoresist 2 2, second photoresist 24 and third photo = min; please refer to "f", and etch J = 2 again: as shown, the metal 31 is evaporated, because the third layer Photoresistance "and K = opening width At the same time, a suspension is formed, so the metal is vapor-deposited. Therefore, when the metal shown in Figure 1 is removed, the process is very complicated = "exposed to the industrial use." It takes a long time and costs two ' In view of this, the main objective of the present invention is to use a single positioning electron beam exposure, and the method using four layers of positive photoresistance junctions to double idle excess, in which the μ — __ two layers of four acoustic crystals are first blocked Electron beam sensitivity

Page 7 200416899 V. Description of the invention (3) " '' and positive photoresistors with different resolutions, only need to be exposed twice by the electron beam, and after the secondary development of the shadow solution, the photoresist can be formed into type I Compared with the conventional method, it requires two positioning exposures, which can save the time of one positioning opening and reduce the manufacturing cost of the component. And the special 1-ga opening formed by this four-layer positive photoresist uses a double gate etching to increase the accumulation. The collapse and lifetime of circuits and increase the yield of component manufacturing. '& /, In order to further disclose the method, advantages and features of the present invention, the preferred embodiments are described below with reference to the accompanying drawings, in which: Figure 2: Figure 炱 Figure 2 Ια is a diagram showing the invention using four layers of light The resistance forms the control pattern of the t-type double gate 0 interception. [Summary] For this reason, the purpose of the present invention is to provide a manufacturing method of sub-micron τ plastic double gate etching. It is used for high-speed field-effect electricity including the following steps: (I) growing a necessary structure on a semiconductor substrate After the epitaxial layer is formed, the first layer of photoresist, the second layer of acoustic layer, and the fourth layer of photoresist are sequentially covered on the epitaxial layer, respectively. The thickness of the fourth layer of photoresist is less than the thickness of the second layer of photoresist, and the thickness of the first layer of photoresist is less than or equal to the thickness of the second layer of photoresist. The photosensitivity of the layer photoresist is greater than that of the second and fourth photoresistors; (II) A single positioning exposure using an electron beam to simultaneously expose the aforementioned first photoresist, second photoresist, and first photoresist. Three-layer photoresist and fourth layer photoresist;

200416899 V. Description of the invention (4) Three layers of photoresist and the photosensitive part of the fourth layer of photoresist to form a T-shaped opening; (IV) Development with the developer (2) again to remove the first layer under the T-shaped opening The photosensitive part of the photoresist does not affect the photosensitive part of the second layer, the third layer, and the fourth layer, and forms an I-type opening; (V) Wetetching under the I-type opening Part of the stupid layer; (VI) dry etching part of the epitaxial layer under the I-type opening; (V II) filling the T-type opening with metal evaporation; (VIII) removing the remaining photoresist, A T-gate is formed. Wherein, after the aforementioned steps of covering the first layer of photoresist, the second layer of photoresist, the third layer of photoresist, and the fourth layer of photoresist, the photoresist is pre-baked for about 20 minutes. The photoresist of the second layer and the photoresist of the fourth layer are composed of polymethyl methacrylate (PMMA). The photoresist of the third layer is composed of polymethyl methacrylate / methacrylic acid (P (MMA / MAA)). Wherein, the aforementioned first layer of photoresist is composed of polymethyl glutarimide (PMGI). The semiconductor base may be gallium arsenide, hafnium phosphide or gallium nitride. The total thickness of the first layer photoresist, the second layer photoresist, the third layer photoresistor, and the fourth layer photoresistor is between 0.7 // m to 1 · 5 // m. The opening of the second layer of photoresist is about 0.1 // m to 0.5 // m.

200416899 V. Description of the invention (5) Among them, the steam (MIBK) is the main one, and the (DeveloplOl), the opening of the front photoresistor is formed, and the opening of the third layer photoresist is much larger than that of the second layer. The former is about 2: 1 to which, the former structure. Among them, the structure of the precursor. Among them, the former structure. The following is provided in order to make the statement based on reality

The plated metal may be a titanium / gold / platinum metal. The developer (1) used was prepared by diluting methyl isobutyl ketone 'with an isopropyl alcohol (IPA) solution. The developing solution (2) used is a tetraethylammonium hydrogen type opening. The opening of the first layer of photoresist, the second layer of second layer of photoresist, and the fourth layer of photoresist. The opening of the fourth layer of photoresist, the opening of the fourth layer on the second layer of photoresist, and the opening of the first layer of photoresist. The metal thickness of the ore is about 300 nm to 50 nm. The ratio of the opening of one layer of photoresist to the opening of the second layer of photoresist is between 4: 1. The worm layer can be formed as a gold half-field effect transistor. The i-crystal layer can be formed as a high electron mobility field-effect transistor. The worm-crystal layer can be placed on top of a heterojunction field-effect transistor. ^ χ The illustration of the moon car Λ Jiaguan example further illustrates that if a person who is familiar with the 4 mesh technology of the present invention can follow this formula]

200416899 V. Description of the invention (6) Single-person electron beam exposure twice for developing money ^ ^ ^ ^ ^ ^ Polar etching method; ^ / Paperman's imitation water T-type double gate is first made of gallium arsenide and phosphorous Indium chemical structure of the first-stupid crystal layer 4 2 and the second :: = = block 4 0 spin-coating method blocked by growth, cover the first " θ 4, and then light 44 first, pre-baked 20 The second bell K is covered with the second worm crystal layer ^ mrnu Ran is covered with a layer of photoresist 52 on the first layer of photoresistance 50 ±, also pre-baked for 20 minutes, then connected to the second layer of photoresist 52 and pre-baked 20 Divide? 56 on the third layer of photoresistor 54, and pre-bake it again. ^ '= Refer to M 2 a as shown in the figure', and then use the electron beam lithography system to customize the exposure, and the electron beam acceleration voltage is 2 〇 κν, the electron beam dose is 40 to 30 OuC 'cm2, and different first photosensitive regions 60 and second photosensitive regions 62 are respectively formed in the four-layer photoresist; see FIG. 2] ^ for development Liquid development to form an I-type opening; etching the damaged one-remote crystal layer 44 of the lower part of the I-type opening, as shown in FIG. 2f, and then metal 7 0 is deposited by electronic snap deposition to make the metal 7 0 Filling In the τ-type opening, the vaporized metal 70 can be titanium, gold, or metal; please refer to the figure 2g, and finally remove the vapor-deposited metal 7 attached to the photoresist with acetone, and then use 1-methyl Substituted 2-azapentanone (stripper) removes the first layer of photoresist 50 and forms a sub-micron T-gate. The aforementioned four layers of positive photoresists are composed of photoresists with different sensitivity of the electron beam. The first photoresist 50 is composed of polymethyl glutarimide (PMGI), the second layer 52 and the fourth layer. Photoresist 5 6 is a low-sensitivity, high-resolution positive photoresist. It consists of polymethyl methacrylate. Page 11 200416899 V. Description of the Invention (7) (PMMA). The second layer of photoresist 5 2 is exposed. After development, Schottky gate contact openings can be formed. Because the layer has the smallest line width after photoresist development, it can form openings in the photosensitive area from 0 · l // m to 0.5 // m;

The thickness T4 of the four-layer photoresist 5 6 is thinner than the thickness T2 of the second layer photoresist 5 2 to form an overhang. The photosensitivity is greater than that of the second layer photoresist 5 2. The opening formed by the second layer of photoresist 5 2 is large, but because its photosensitivity is lower than that of the third layer of photoresist 5 4, the line width of this opening is smaller than that of the second layer of photoresist 5 2, so it will form a hang. Hanging is used as an auxiliary metal lifter, which can improve the flatness of the cross section of the deposited metal 70 and increase the yield.

In addition, the third layer photoresist 54 is a high (electron beam) photosensitivity positive photoresist. Its composition is polymethylmethacrylate / fluorenyl acrylic acid (P (MMA / MAA)), which can form a thicker light. The thickness T3 of the third layer photoresist 5 4 is greater than the thickness T2 of the second layer photoresist 5 2, and the thickness T2 of the second layer photoresist 5 2 is greater than the thickness T4 of the fourth layer photoresist 56. Because of its high (electron beam) photosensitivity, after the electron beam exposure, the photosensitive part is larger. After the developer is developed, a large line width opening can be formed, which is wider than the second and fourth layers of photoresist. 5 The openings of 2, 5 and 6 are large, and the ratio of the opening (line width) of the third layer of photoresist 5 4 and the second layer of photoresist 5 2 is about 2: 1 to 4: 1. As for the developing step, the second layer of photoresist 5 2, the third layer of photo resist 5 4 and the fourth layer of photo resist 5 6 are developed by the developing solution (1); please refer to FIG. 2 c In order to form a T-shaped opening with a wide top and a narrow bottom, the developing solution (1) is mainly composed of methyl isobutyl ketone (MIBK) and isopropyl alcohol.

Page 12 200416899 V. Description of the invention (8) (IPA) The solution is diluted.

Vi) Photosensitive areas 62 of the second layer of photoresist 52, the third layer of photoresist 54 and the fourth layer of photoresistance can be developed at the same time. 2 photosensitive area 60, developing solution (2), composed of hydrogenated tetraethene (Devei0pm), developed to form I-type openings without affecting the second layer of photoresist 5 2 and the third layer of photo resist 5 4 And the shape of the fourth layer of photoresistor 56; please refer to figure 2d: the total thickness of the aforementioned four layers of photoresistor is between 0.7um to 丄 .5um, and then wet etching is used; please See figure 2e and dry etching; see figure 2f, the second stupid layer 44 in the lower part of the mold opening forms a double closed-electrode etch process. 〇 Its thickness is about 300 ⑽ to 5000 nm. In the step of removing the vapor-deposited metal 70, the wafer after the vapor-deposited metal 70 is immersed in acetone, because the second photoresist 52, the third photoresist 54 and the fourth photoresist 56 can be used. Dissolved in acrylics to 'turn off the vapor-deposited metal Y 0 outside the T-type interpolar region', and then immerse the wafer in 丨 -methylazapentanone (Stripper) to remove the first layer of photoresist 5 〇 Please refer to Section 2 h Figure. The manufacturing method of the sub-micron T-gate of the present invention is mainly applied to gold half field effect transistors (MESFETs) and high electron mobility field effect transistors (HEMT) 'and heterojunction field effect transistors (hfet). That is, different elements of the stupid crystal layer structure will be formed. This type of gold half-field effect transistor is composed of a source, a drain, a gate, and a channel. The source and the drain are ohmic contacts between metal and semiconductor, and the gate It is a metal-semiconductor contact. The conduction electrons pass from the source through the conduction channel to the drain, which is the drain current, and the gate is

Page 13 200416899 V. Description of the invention (9) The magnitude of the modulating (m o d u 1 a t e) non-polar current. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and retouching without departing from the spirit and scope of the present invention. The scope of protection of the invention shall be determined by the scope of the attached patent application.

Page 14 200416899 Brief description of the drawings [Simplified description of the drawings] Figures 1a to 1i are drawings showing the conventional technique of using two positioning exposures to develop etching to form a T-gate and double-gate engraving technique. Figures 2a to 2h are diagrams illustrating a manufacturing method for forming a sub-micron T-type double gate etch using a single positioning electron beam exposure and two development etchings of the present invention. [Illustration of drawing number] substrate 1 0 first epitaxial layer 1 2 second epitaxial layer 1 4 photoresist layer 1 6 first layer photoresist 20 second layer photoresist 22 third layer photoresist 2 4 vapor-deposited metal 3 1 Base 4 0 First epitaxial layer 4 2 Second epitaxial layer 4 4 First layer photoresistor 50 Second layer photoresistor 52 Third layer photoresistor 54 Fourth layer photoresistor 56 First photosensitive area 6 0 No. Two photosensitive areas 6 2 Evaporated metal 7 0 Thickness of second photoresistor T2 Thickness of third photoresistor T3 Thickness of fourth photoresistor T 4

Page 15

Claims (1)

Sixth, the scope of patent application 1. A submicron τ-type double gate etched Yushang speed field effect transistor element, which includes the following steps. '^ (!) * :! The necessary structure growing on the conductor base is a crystal After the layer, the first layer of photoresist, the second layer of photoresist, the third layer of photoresistance, and the fourth layer of photoresist are sequentially covered on the Rong Maojing layer, respectively. "The thickness of the third layer of photoresist is greater than that of the fourth layer. The thickness of the photoresist, the thickness of the fourth photoresist is less than the thickness of the second photoresist, and the thickness of the first photoresist is less than or equal to the thickness of the second photoresist 'and the first photoresist The photosensitivity of the electron beam is greater than that of the second and fourth photoresistors; (II) A single positioning exposure using the electron beam, while exposing the aforementioned first photoresist, second photoresist, and third layer simultaneously Photoresist and the fourth layer of photoresist; (III) developing with a developing solution (1), removing the photosensitive part of the second layer, the third layer of photoresist and the fourth layer of photoresist to form a τ-shaped opening; (IV) Develop with developer solution (2) again, remove the photosensitive part of the first layer of photoresist under the τ-type opening without affecting the second layer The photoresist, the third layer of photoresist, and the photosensitive part of the fourth layer of photoresist to form an I-type opening; (V) wet etching part of the epitaxial layer under the I-type opening; (VI) dry type (Etching) part of the epitaxial layer under the I-type opening; (VII) filling metal into the τ-type opening by evaporation; (VIII) removing the remaining photoresist to form a T-type gate. The manufacturing method according to item 1 of the scope of patent application, wherein the first layer is covered with the first layer of photoresist, the second layer of photoresist, the third layer of photoresist, and the fourth layer Page 16 200416899 VI. Steps for applying photoresistance in the scope of patent application 3, such as the application of the aforementioned second layer of light (PMMA) composition 4, such as the application of the aforementioned third layer of light (MMA / MAA)) Ϊ 5, such as the application of the aforementioned first Layer light 6, such as the aforementioned semiconductor base 7, the total thickness of the first layer of the aforementioned layer is 0.8, such as the aforementioned second layer of the optical layer 9, such as the applied vapor-deposited metal may be 10, as used in I use isopropyl 1 1, as in, and use: (Deve1 op 10 1 method, in which acrylic (p) each pre-baked the photoresist about 2.08 $ The manufacturer mentioned above is 77, and the photoresistor and the fourth layer of photoresistor are made of polymethyl. Among them, the manufacturer mentioned in the patent scope item 1 is made of polymethacrylate. / Methyl Please remove the resistance of the producer described in item 1 of the patent scope by using polymethyl glutarmidine (PMGI ', where the method of manufacture described in item 1 of the patent scope) is graded. The gallium nitride, indium phosphide, or nitride is listed in the manufacturing method described in item 1 of the patent scope, the second layer photoresistor, and the third layer photoresistor. 'Among them, "to 1. · 5. The four-layer photoresist asks for the manufacturing method described in item 1 of the patent scope to block the opening of about 0.1 · m to 0 · 5 # m. The manufacturing method is titanium / gold / platinum metal. The manufacturing solution (1) described in the first patent application range is diluted with a methyl isobutyl snapper (Ml （alcohol (IPA) solution). The manufacturing method (2) described in item 1 of the patent scope is hydrogenated with tetraethyl ether. Among them, it is 200416899 6. Application for patent scope 1 2 and the production method described in item 1 of patent scope , Where the aforementioned T-shaped opening is composed of the opening of the first layer of photoresist, the opening of the second layer of photoresist, the opening of the third layer of photoresist, and the opening of the fourth layer of photoresist, and the opening of the third layer of photoresist The opening of the photoresist is larger than the opening of the fourth layer, the opening of the fourth layer is larger than the opening of the second layer, and the opening of the first layer is larger than the opening of the second layer. The production method according to item 1, wherein the thickness of the vapor-deposited metal is about 300 n m to 500 nm. 1 4. The manufacturing method according to item 7 of the scope of patent application, wherein the ratio of the opening of the third layer of photoresist and the opening of the second layer of photoresist is about 2: 1 to 4: 1. 15. The manufacturing method according to item 1 of the scope of patent application, wherein the epitaxial layer can be formed into a structure of a gold half field effect transistor. 16. The manufacturing method according to item 1 of the scope of patent application. The epitaxial layer can be formed as a structure of a high-electron mobility field effect transistor. 17. The manufacturing method according to item 1 of the scope of patent application, wherein the epitaxial layer can be formed into a structure of a heterojunction field effect transistor. Page 18