CN102180440A

CN102180440A - Preparation method of nano-gap electrode in micro-nano electromechanical device

Info

Publication number: CN102180440A
Application number: CN2011100852402A
Authority: CN
Inventors: 于晓梅; 于侃; 王晓菲
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2011-04-06
Filing date: 2011-04-06
Publication date: 2011-09-14

Abstract

The invention provides a preparation method of a nano-gap electrode in a micro-nano electromechanical device, which belongs to the field of micro-nano electromechanical systems. According to the preparation method, an appropriate material is selected to prepare a sacrificial layer, and the preparation method comprises the following steps of: firstly, preparing a nano-scale side wall structure of the sacrificial layer in a mode of back etching, wherein the side wall needs to have a certain height; secondly, depositing a layer of thin metal layer or other electrode materials; and thirdly, selectively corroding the side wall material of the sacrificial layer, wherein the metals or other electrode materials attached to the side wall are corroded together, and a gap is formed at the position of the side wall. The nano-gap electrode is prepared by keeping the thickness of the sacrificial layer side wall in a nano scale. The preparation method is compatible with the conventional semiconductor processing technique, is easy for large-scale production, and is low in cost.

Description

The preparation method of nano-gap electrode in a kind of micro-nano mechanical device

Technical field

The present invention relates to the preparation method of nano-gap electrode in a kind of micro-nano mechanical device, belong to the minute mechanical and electrical system field.

Background technology

Along with dwindling of silicon device characteristic size, increasing for the demand of the manufacture craft of micro-nano structure.Nano-gap electrode is the foundation of MEMS device.Nano-gap electrode is for the character that detects the nanoscale material, and structure quantum device, biology sensor aspect have important use.

The technology mode of making nano-gap electrode has electron beam lithography method, atomic force microscope nanometer etching method, contact break method and galvanoplastic etc.Wherein, (1) electron beam has the wavelength shorter than normal optical, owing to adopt electric field accurately to focus on, therefore can obtain higher resolution ratio, and can under computer control, directly write arbitrarily, but efficient is low, cost an arm and a leg, and the kindred effect problem that incident beam produces makes its very difficult large-scale application; (2) contact break method advantage is that method is simple, can prepare the small electrode in gap, but is not easy to produce in batches; (3) galvanoplastic are prepared the metal electrode of gap in micron dimension by traditional photoetching technique, then deposit is placed electroplate liquid, metallic reducing in the electroplate liquid is deposited on electrode surface, this method simple and effective, but can only be to the operation one by one of concrete device; (4) electron transfer method is with low cost, but prepared electrode profile is irregular, and preparation process is wayward, is difficult to make on a large scale.

Summary of the invention

The present invention proposes a kind of preparation method of the nano-gap electrode based on micromechanical process.This method adopts the width of sacrifice layer sidewall structure definition nano gap, can not be subjected to the influence of lithographic accuracy.

The preparation method of nano-gap electrode in the micro-nano mechanical device provided by the invention, concrete steps comprise:

1) deposit one deck dielectric material is selected the supplementary structure layer of the suitable material of a kind of thickness of deposit as side wall again as insulating barrier on substrate, and the supplementary structure layer material should have corrosion preferably to select ratio with insulating layer material;

2), photoetching, behind the definition supplementary structure mask layer figure, dry etching supplementary structure layer material forms the steep supplementary structure figure of sidewall, for follow-up sacrifice layer deposit is prepared;

3) deposit one deck sacrificial layer material, the thickness of sacrifice layer determines the width of last nano gap, sacrificial layer material will have good corrosion to select ratio simultaneously with follow-up nano-gap electrode material;

4) return and carve sacrifice layer, general selectivity over etching 3 seconds, exposed fully up to supplementary structure layer upper surface, because the anisotropic etching character of dry etching, can remain attached to the sacrifice layer of supplementary structure layer sidewall;

5) wet etching substrate select the corrosive liquid of corrosion supplementary structure layer for use, thereby protection sacrifice layer sidewall structure is not corroded, the sacrifice layer side wall of remaining nano-width only after the supplementary structure layer etches.

6) the thin electrode material of deposit one deck, this material is metal or the good material of other electric conductivity, needing has good corrosion selectivity with the sacrifice layer spacer material;

7) wet etching sacrifice layer side wall, because electrode material can not cover sidewall structure fully, corrosive liquid horizontal brill of meeting and corrosion sacrificial layer structure when corrosion side wall sacrifice layer, the electrode material that covers on the side wall can be eroded by selectivity together with the sacrifice layer side wall, forms final nano-gap electrode structure.

Method provided by the invention has following advantage:

Adopt simply, operation repeatably, make the nano-device of high integration, and not limited by the photoetching minimum dimension, do not need to adopt beamwriter lithography.

By the silicon nano-gap electrode structure that said method is made, can be applicable to the preparation of multiple micro-nano mechanical sensor, can make the Bio-MEMS sensor of detection of biological bioactive molecule, can make the quantum device of research nanometer spintronics etc.

Description of drawings

Fig. 1 (a)-(d) is the process flow diagram of embodiment of the invention making nano gap, wherein: (a) deposit insulating medium layer; (b) deposit supplementary structure layer; (c) photoetching and etching form the supplementary structure layer; (d) deposit sacrificial layer material; (e) return sacrifice layer formation at quarter sacrifice layer side wall; (f) selective corrosion supplementary structure layer material forms the side wall sacrifice layer; (g) sputter thin metal layer or main structure layer material; (h) corrosion side wall sacrifice layer forms the nano gap structure;

Fig. 2 is the stereoscan photograph that utilizes the nano-gap electrode that the present invention makes.

The specific embodiment

Below in conjunction with the invention will be further described by embodiment, but the present invention is not limited to following examples.

The process chart of on silicon substrate, making the nano metal gap shown in Figure 1, concrete steps are as follows:

1) on silicon substrate 1 LPCVD thickness be 100nm to 120nm silicon nitride layer 2, as the insulating barrier of metal electrode, see Fig. 1 (a);

2) LPCVD deposit polysilicon layer 3, thickness 800nm as the supplementary structure layer 3 of subsequent oxidation layer deposit, sees Fig. 1 (b);

3) do mask dry etching polysilicon layer behind the photoetching development with photoresist, select ASE for use,, be convenient to follow-up side wall sacrifice layer 4 deposits, as Fig. 1 (c) to form the steep supplementary structure figure of sidewall;

4) LPCVD silicon oxide deposition layer 4, thickness 100nm, the width of its thickness decision side wall sacrifice layer, because the good spreadability of LPCVD, sidewall width is bigger slightly than deposition thickness 100nm, as Fig. 1 (d);

5) return oxide layer 4 at quarter, etch thicknesses 100nm, exposed fully to polysilicon supplementary structure laminar surface, be convenient to follow-up TMAH corrosion polysilicon supplementary structure figure, as Fig. 1 (e).

6) water-bath is 80 ℃, TMAH wet etching polysilicon, because polysilicon and the good corrosion selectivity of silica, the monox lateral wall sacrifice layer is kept, as Fig. 1 (f).

7) sputter Cr/Au

Metal level 5 is as electrode material, as Fig. 1 (g).

8) BHF ultrasonic erosion silica erodes the sacrifice layer side wall, and related removing attached to the thin metal layer on the side wall finally forms the nano-gap electrode structure, as Fig. 1 (h).

Said method has realized that embodiment of the present invention-utilize side wall sacrifice layer process forms the nano-gap electrode structure, and the live width of width adjustment nano gap that can be by the sacrifice layer side wall.

Fig. 2 is the stereoscan photograph that utilizes the nano-gap electrode that the present invention makes, and gap width is about 110nm.

More than describe with the description of the drawings and be intended to illustrate embodiment of the present invention, scope of the present invention is only limited by the claim of being paid.Those skilled in the art can carry out the change or the change of various necessity to the present invention, but should not break away from the present invention.

Claims

1. the preparation method of a nano-gap electrode, its step comprises:

1) on substrate deposit one deck insulating materials as insulating barrier, deposit one supplementary structure layer again; This supplementary structure layer material should have certain corrosion to select ratio with insulating layer material;

2) behind photoetching, the definition supplementary structure mask layer figure, dry etching supplementary structure layer material forms the steep supplementary structure figure of sidewall;

3) deposit one deck sacrificial layer material, the thickness of sacrifice layer are the width of nano-gap electrode, and this sacrificial layer material should have certain corrosion to select ratio with the supplementary structure layer material simultaneously;

4) return that to carve sacrifice layer exposed fully up to supplementary structure layer upper surface, because the anisotropic etching character of dry etching, be retained attached to the sacrifice layer of supplementary structure layer sidewall;

5) select for use the corrosive liquid of corrosion supplementary structure layer to corrode substrate, because sacrificial layer material and supplementary structure layer material have certain corrosion to select ratio, so after finishing the corrosion of supplementary structure layer, the sacrifice layer side wall is retained;

6) deposit one deck electrode material, this electrode material has certain corrosion to select ratio with the sacrifice layer spacer material;

7) wet etching sacrifice layer side wall, when corrosion sacrifice layer side wall, the electrode material that covers on the side wall can be eroded by selectivity together with the sacrifice layer side wall, finally forms nano-gap electrode in the side wall position.

2. preparation method as claimed in claim 1 is characterized in that, in the step 1), described supplementary structure layer is a polysilicon, and thickness is 600nm-2 μ m.

3. preparation method as claimed in claim 1 is characterized in that, in the step 3), described sacrifice layer is a silica, and silicon oxide thickness is less than 100nm.

4. preparation method as claimed in claim 1 is characterized in that, in the step 6), described electrode material is metal or the good material of other electric conductivity.