CN102701139A - Preparation method of solid state chemistry micro-propeller - Google Patents

Abstract

The invention relates to a manufacturing method of a micro-propeller, which belongs to the field of micro-electro-mechanical system manufacturing. This method comprehensively utilizes metal aluminum thin film technology and metal lift-off process. First, metal aluminum is sputtered on the surface of the silicon wafer, photolithography, and aluminum is used as a mask to DRIE to obtain the combustion chamber and nozzle; , and then obtain copper wires and copper pads through a stripping process. The beneficial effects of the present invention are: using ordinary photoresist and metal aluminum film to obtain a deep combustion chamber and nozzle structure on the surface of the silicon wafer, avoiding the use of thick glue, using the metal stripping process to obtain an ignition circuit, avoiding metal wetness The safety of the etchant and the uncontrollable corrosion rate during the etching process by the method reduce the difficulty of the process and ensure the smooth progress of the production process.

Description

Preparation method of miniature solid chemical propulsion

technical field

The invention relates to a manufacturing method of a micro-propeller, which belongs to the field of micro-electro-mechanical system manufacturing.

Background technique

MEMS thrusters are a new direction for the development of micro-propulsion systems, creating a new way for the research of micro-satellites, especially nano/pico-satellite propulsion systems, and solid chemical micro-thrusters based on MEMS technology have simple structure, low power consumption, With a series of advantages such as no moving parts, high integration, and good reliability, it has become a new research hotspot at home and abroad.

Referring to Fig. 4, the miniature solid-state chemical thruster includes a bonded silicon chip 1 and a glass chip 7; the surface 14 of the silicon chip 1 is concavely formed to form a combustion chamber 5 and a nozzle 15; the two sides of the combustion chamber 5 have linear lower wire grooves 16 respectively And the upper wire groove 3; the glass sheet 7 is made up of heat-resistant glass 17 and the ignition circuit structure on it, the ignition circuit structure includes the igniter 18 at the corresponding position of the combustion chamber 5, and the two ends of the igniter 18 are respectively connected through the upper ignition wire 10 and the lower ignition wire 11 are connected to the upper pad 12 and the lower pad 13; in order to improve the ejection speed, the nozzle 15 has a convergent-divergent shape.

The quality of the technological process and parameters in the preparation method of the micro-solid-state chemical propulsion directly affects the performance of the micro-propulsion, and even relates to the smooth progress of the manufacturing process, so the selection of the technological process is the key to improving the performance of the micro-propulsion.

When using the DRIE process to process the combustion chamber and the nozzle with a convergent-divergent shape on the surface of the silicon wafer, the photoresist needs to have a strong protective ability, and the use of ordinary photoresists has limitations in deep etching applications, so Zhang et al. The article "Development of a solid propellant microthruster with chamber and nozzle etchedon a wafer surface" uses thick glue for deep etching to obtain the combustion chamber and nozzle structure, then conducts surface oxidation treatment of the structure, and finally performs silicon and glass bonding to obtain a microthruster. For thruster samples, if ordinary photoresist and Zhang et al.'s processing technology are used, it will be difficult to obtain a deeper structure; Zhang et al. A series of process steps such as etching, sputtering, stripping, re-sputtering, and wet etching of metals are used to obtain exposed ignition resistors, but the strong selectivity, safety, and controllability of the etching rate of the metal etching solution are difficult to grasp , making the process of wet etching metal more difficult.

Contents of the invention

In order to overcome the disadvantages that ordinary photoresists cannot obtain deeper combustion chambers, nozzle structures and wet etching metal processes in the prior art, the present invention proposes a method for preparing micro-solids using metal aluminum thin film technology and metal stripping technology. The method of chemical propulsion.

The technical solution adopted by the present invention to solve the technical problem of the combustion chamber and nozzle structure is: refer to FIG. 1 , and the technical solution adopted by the present invention to solve the technical problem of the ignition circuit is: refer to FIG.

The preparation method of the miniature solid-state chemical thruster that the present invention proposes is:

The first step, as shown in Figure 1 (a), is to clean the ordinary silicon wafer 1; then apply photoresist 2 on the silicon surface, photolithography, development, and ICP etching to obtain the lower wire groove 16 and the upper wire groove 3. The depth of the wire groove 16 and the upper wire groove 3 is 400nm to 550nm, and the width is 350 μm to 450 μm;

The second step, as shown in Figure 1(b), removes the photoresist, cleans the surface of the silicon wafer, sputters metal aluminum 4, the thickness of the metal aluminum 4 is 100nm to 300nm, and then spin-coats photoresist on the aluminum surface, photolithography , developing, using wet etching to remove the aluminum film in the exposed area, and then DRIE to obtain the combustion chamber 5 and nozzle 15 at the same time, with a depth of 300 μm to 550 μm.

The third step, as shown in Figure 1(c), removes the remaining aluminum film, dry-processes the silicon wafer, the thickness of the silicon dioxide 6 is 200nm to 600nm, and cleans the oxide film with a hydrofluoric acid solution to obtain a clean combustion chamber 5 And nozzle 15 structure.

The fourth step, as shown in Figure 2 (a), is to clean the glass sheet 7, apply photoresist 2 on the surface of the glass sheet, photolithography, and develop to obtain the igniter 18, the upper ignition wire 10, the lower ignition wire 11, and the upper pad 12 and the pattern of the lower pad 13, metal 8 is sputtered on the surface of the glass plate coated with photoresist, the metal film 8 is generally a metal material with a melting point greater than 1500°C, and the thickness of the metal film 8 is 100nm to 350nm.

The fifth step, as shown in Figure 2(b), is to peel off the photoresist to obtain the igniter 18, apply photoresist 2 on the glass sheet of the metal film 8, photolithography, and develop to obtain the pattern of the ignition wire area and the pad area, Metal film 9 is sputtered on the glass sheet 7 surface that is coated with photoresist 2, and metal film 9 is generally the metal material with good electrical conductivity, as copper, platinum, gold etc., and the thickness of metal film 9 is 100nm-350nm, removes light again resist to obtain metal wires and metal pads, as shown in Figure 2(c).

The sixth step, as shown in Figure (3), is to connect the silicon chip with the combustion chamber and nozzle structure and the glass chip with the ignition circuit by bonding process to obtain a micro solid chemical thruster.

The beneficial effects of the present invention are: using ordinary photoresist and metal aluminum film to obtain a deep combustion chamber and nozzle structure on the surface of the silicon wafer, avoiding the use of thick glue, using the metal stripping process to obtain the ignition circuit, avoiding the metal wet The safety problem of the etchant and the uncontrollable problem of the corrosion rate during the etching process by the method reduce the difficulty of the process and ensure the smooth progress of the production process.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the process flow schematic diagram of micropropulsion combustion chamber and nozzle in the embodiment.

Fig. 2 is a schematic diagram of the technological process of the ignition circuit of the micro-propeller in the embodiment.

Fig. 3 is a schematic diagram of the bonded micro-propulsion in the embodiment.

Fig. 4 is the schematic diagram of the miniature solid-state chemical thruster prepared in the embodiment

In the figure, 1-silicon wafer, 2-photoresist, 3-upper wire groove, 4-metal aluminum, 5-combustion chamber, 6-silicon dioxide, 7-glass sheet, 8-metal film, 9-metal film .

Detailed ways

Provided a kind of preparation method of the miniature solid-state chemical thruster as shown in Figure 4 in the present embodiment, this miniature solid-state chemical thruster comprises the silicon slice 1 and the glass slice 7 of bonding; Silicon slice 1 surface 14 concaves form The combustion chamber 5 and the nozzle 15; the two sides of the combustion chamber 5 have linear lower wire grooves 16 and upper wire grooves 3; The igniter 18 at the corresponding position of the chamber 5, the two ends of the igniter 18 are respectively connected to the upper pad 12 and the lower pad 13 through the upper ignition wire 10 and the lower ignition wire 11; the material of the igniter 18 is chromium, and the upper ignition wire 10 , the material of lower ignition wire 11, upper pad 12 and lower pad 13 is copper; In order to improve the ejection speed, nozzle 15 has a convergent-divergent shape, and the throat at the communication place of combustion chamber 5 and nozzle 15 is Arc shape. The manufacturing process of the miniature solid-state chemical thruster in this embodiment is:

The first step, as shown in Figure 1 (a), is to clean the ordinary silicon wafer 1; then apply photoresist 2 on the silicon surface, photolithography, development, and ICP etching to obtain the lower wire groove 16 and the upper wire groove 3. The depth of the wire groove 16 and the upper wire groove 3 is 500nm, and the width is 450 μm;

The second step, as shown in Figure 1(b), removes the photoresist, cleans the surface of the silicon wafer, sputters metal aluminum 4, the thickness of the metal aluminum 4 is 200nm, and then spin-coats photoresist on the aluminum surface, photolithography, and development , using wet etching to remove the aluminum film in the exposed area, and then DRIE to simultaneously obtain the combustion chamber 5 and the nozzle 15, both of which have a depth of 500 μm;

The third step, as shown in Figure 1(c), removes the remaining aluminum film, dry-processes the silicon wafer, and the thickness of silicon dioxide 6 is 500nm, and cleans the oxide film with hydrofluoric acid solution to obtain a clean combustion chamber and nozzle structure ;

The fourth step, as shown in Figure 2(a), is to clean the glass sheet 7, apply photoresist 2 on the surface of the glass sheet, photolithography, and develop to obtain the igniter 18, the upper ignition wire 10, the lower ignition wire 11, and the upper pad 12 and the pattern of the lower pad 13, the metal film 8 is sputtered on the surface of the glass sheet coated with photoresist. In the present embodiment, the material of the metal film 8 is chromium, and the thickness of the metal film 8 is 300nm;

The fifth step, as shown in Figure 2(b), is to peel off the photoresist to obtain an igniter 18 made of chromium, and apply photoresist 2 on the glass sheet coated with metal film 8, photolithography, and development to obtain the upper ignition wire 10 , lower ignition wire 11, the pattern of upper pad 12 and lower pad 13, sputtering metal film 9 on the surface of glass plate 7 coated with photoresist 2, the material of metal film 9 is copper in the present embodiment, the material of metal film 9 The thickness is 300nm, and then the photoresist is removed to obtain an upper ignition wire 10, a lower ignition wire 11, an upper pad 12 and a lower pad 13 of copper, as shown in FIG. 2(c);

The sixth step, as shown in Figure 3, is to connect the silicon chip with the combustion chamber and nozzle structure and the glass chip with the ignition circuit by bonding process to obtain a micro propulsion sample.

Claims (3)

1. the preparation method of miniaturized solid-state chemical propeller is characterized in that, comprises the steps:

The first step is cleaned common silicon chip (1); Obtain lower wire groove (16) and upper conductor groove (3) in silicon face resist coating (2), photoetching, development, ICP etching again;

Second step, remove photoresist, the cleaning silicon chip surface, at aluminium surface spin coating photoresist, develop, utilize wet etching remove the aluminium film of exposure area again by photoetching for splash-proofing sputtering metal aluminium (4), and then DRIE obtains combustion chamber (5) and nozzle (15) simultaneously;

The 3rd step, remove remaining aluminium film, the dry oxidation silicon chip adopts hydrofluoric acid solution to clean oxide-film, obtains bright and clean combustion chamber (5) and nozzle (15);

The 4th step; Glass cleaning sheet (7); Obtain igniter (18) in glass sheet surface resist coating (2), photoetching, development, go up harness (10), down-firing lead (11), go up the figure of pad (12) and following pad (13), scribbling the glass sheet surface splash-proofing sputtering metal (8) of photoresist;

The 5th step; Stripping photoresist; Obtain igniter (18), resist coating on the sheet glass of metal film (8) (2), photoetching, development obtain the figure of harness district and pad area, at the sheet glass that scribbles photoresist (2) (7) surface sputtering metallic film (9); Remove photoresist again, obtain plain conductor and metal pad;

In the 6th step, the silicon chip that will have combustion chamber and nozzle arrangements utilizes bonding technology to be connected with the sheet glass with firing circuit, obtains the miniaturized solid-state chemical propeller.

2. the preparation method of miniaturized solid-state chemical propeller according to claim 1 is characterized in that, metal film (8) is a fusing point greater than 1500 ℃ metal material in said the 4th step.

3. the preparation method of miniaturized solid-state chemical propeller according to claim 1 is characterized in that, the material of metallic film (9) is copper, platinum or gold in said the 5th step.

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