CN1604303A - Interconnection method based on nano carbon tubes - Google Patents

Abstract

This invention discloses a nanometer carbon tube connection method, which comprises the following steps: to vapor an aluminum film with 20 to 200 nm thickness on the silicon base by electron beam; to adopt anodic oxidation to process the film into multiple-hole alumina mode plate; to process blind plate with holes according to connection need of silicon base; to lay the blind plate on the alumina mode plate and to grow katalyst metal in the bottom of hole base of the alumina mode plate by use of micro wet method; to adopt chemical gas phase deposition method to process nanometer carbon beam.

Description

A kind of interconnecting method based on CNT (carbon nano-tube)

Technical field

The present invention relates to a kind of interconnecting method based on CNT (carbon nano-tube) (CNTs).

Background technology

Along with the fast development of microelectric technique, chip size increases day by day (from original 4.5cm ²Increase to 9.4cm ²), I/O port increasing (being increased to more than 8000) from original 1600, device speed improves (bringing up to 3.6GHz from original 1.2GHz) day by day, and maximum power dissipation increases (increasing to 183W from original 90W) day by day.At present, characteristic size emerges less than the technology of 100nm.According to IRST 2003 (international semiconductor blueprints in 2003), to realize 90nm technology in 2005, this just requires the interconnect pitch will be less than 50um, part photoelectric device interconnect pitch will be less than 10um, so little pitch will require the I/O end to surpass 10,000, the speed of transmission information surpasses megabits per second, and power consumption surpasses 200W.

Meanwhile, the rapid progress of nano material is worth IC encapsulation circle to pay close attention to.People prepare the nanometer carbon pipe array (to hundreds of nanometers, to several microns, length is from several microns to several millimeters from several nanometers for spacing from several for external diameter) of high orientation by several different methods.As, be template with mesoporous silicon and aluminium oxide, by the method for chemical vapour deposition (CVD); Based on coated glass, quartz glass,, the report of large tracts of land (tens millimeters * tens millimeters) growth is arranged all by self-orientating method etc.The progress of nano-functional material aspect is for encapsulation and interconnection under the development nanoscale provide strong support.But relevant on alumina formwork growing nano carbon pipe report, all only be confined to growing nano carbon pipe on the monoblock template, can't be used for chip interconnect.

At present, also do not work out both at home and abroad ripe nanoscale interconnection technology, have only the research report of the interconnection form of very a spot of self assembly based on CNT (carbon nano-tube).For example, the breadboard Y.Homma of Nippon Telegraph ﹠ Telephone public company basic research, at its paper of delivering " Interconnection ofnanostructures using carbon nanotubes " (Physica B Volume:323, Issue:1-4, October, 2002, pp.122-123) mention in: have on regular pattern (equally distributed convex line or salient point) silica-based, make catalyst with ferric oxide nanometer particle, by methane chemical vapor deposition growth CNT (carbon nano-tube), research is observed the part CNT (carbon nano-tube) equally distributed boss or salient point is coupled together.The interconnection form of this self assembly based on CNT (carbon nano-tube), because enchancement factor is too many, the diameter of uncontrollable CNT (carbon nano-tube), length and the direction of growth are difficult to obtain required interconnection structure.

Summary of the invention

The objective of the invention is to propose a kind of interconnecting method based on CNT (carbon nano-tube), this method can overcome the randomness based on the interconnection form of CNT (carbon nano-tube) self assembly, effectively control the direction of growth, diameter and the length of carbon nanotubes, obtain required interconnection structure, satisfied fine pith (less than 20 μ m), big power consumption (surpassing 200watts), high-frequency (20～50GHz) chip interconnect requirement.

For achieving the above object, the technical solution used in the present invention is: a kind of interconnecting method based on CNT (carbon nano-tube) comprises

(1) on silicon base, deposited by electron beam evaporation one layer thickness is the aluminium film of 20～200nm;

(2) adopt anode oxidation method that the aluminium film preparation is become porous alumina formwork;

(3) according to the interconnection needs of silicon base, adopt exposure, wet development and dry etching, make the mask plate that has through hole;

(4) mask plate that will have a through hole places on the porous alumina formwork, needs the position alignment that interconnects on the through hole of mask plate and the silicon base, adopts the hole bottom plantation catalyst metals of little wet impregnation method at alumina formwork;

(5) on catalyst metals, adopt the method for chemical vapor deposition to prepare carbon nanotubes.

Above-mentioned catalyst metals can be Fe or Co or Ni.

The invention has the beneficial effects as follows:

(1) can access diameter by the present invention is that 5～10 μ m, length are 500～800nm carbon nanotubes consistent with the direction of growth, as required interconnection structure.

(2) because CNT (carbon nano-tube) has nano level size, as interconnection material, carbon nanotubes can satisfy the chip interconnect requirement of fine pith (less than 20 μ m).

(3) owing to good electromagnetic property and the thermal characteristic of CNT (carbon nano-tube), as interconnection material, carbon nanotubes can satisfy big power consumption (surpassing 200watts), high-frequency (20～50GHz) chip interconnect requirement.

(4) because the good electromagnetic property of CNT (carbon nano-tube), carbon nanotubes can solve the problem of electromigration, delay, cross-talk and switching noise aspect that interconnection brings better than present interconnection material.

(5) because the good thermal characteristic of CNT (carbon nano-tube), carbon nanotubes can solve the problem of the thermal cycle that interconnection brings better than present interconnection material.

(6) because the good mechanical characteristic of CNT (carbon nano-tube), carbon nanotubes can solve the problem of the vibration/shock that interconnection brings better than present interconnection material.

(7) Woelm Alumina Al ₂O ₃Template can be used as the inter-level dielectric between silicon base and the metal level, need not to make other oxide layer, and subsequent technique is simplified.

Description of drawings

Fig. 1～Figure 10 is the process chart of an embodiment of the present invention, wherein:

Fig. 1 is the schematic diagram of evaporation layer of aluminum film on silicon base.

Fig. 2 is the vertical view of Fig. 1.

The Woelm Alumina Al that Fig. 3 obtains for the oxidation of aluminium film ₂O ₃The schematic diagram of template and silicon base.

Fig. 4 is the vertical view of Fig. 3.

Fig. 5 is the schematic diagram that has the mask plate of through hole.

Fig. 6 is the vertical view of Fig. 5.

Fig. 7 is at Woelm Alumina Al ₂O ₃The schematic diagram of bottom, the hole plantation catalyst metals of template.

Fig. 8 is the vertical view of Fig. 7.

Fig. 9 is the schematic diagram of growing nano carbon tube bank on catalyst metals.

Figure 10 is the vertical view of Fig. 9.

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

A kind of interconnecting method based on CNT (carbon nano-tube) comprises

(1) on the silicon base 1 of cleaning, deposited by electron beam evaporation one layer thickness is the pure aluminium film 2 of 50nm, as shown in Figure 1 and Figure 2.The purity of aluminium film is preferably more than 99.999%, and the condition of evaporation can be: electron gun current is 0.5A, and electron gun voltage is 10kV, and vacuum degree is 4 * 10 ^-6Pa, growth rate is 1.5nm/s.

(2) adopt common anode oxidation method that aluminium film 2 is prepared into porous alumina formwork 3

There is the silicon base 1 of aluminium film 2 to be fixed in the electrolysis tank evaporation, adding concentration in electrolysis tank is sulfuric acid or phosphoric acid or the oxalic acid solution of 0.3mol/L, the aluminium film is as anode, nickel or platinum wire are as negative electrode, between anode and negative electrode, connect the D.C. regulated power supply of 40V, at 1.0 ℃, oxidation 48 hours is prepared into Woelm Alumina Al with aluminium film 2 ₂O ₃Template 3, its hole 4 preferably evenly distribute, and the average diameter in hole 4 is 20nm, and density is about 6.0 * 10 ¹⁰Individual/cm ², and hole 4 is through hole, in order to avoid in subsequent technique, cause short circuit, and as shown in Figure 3, Figure 4.

By changing oxidation voltage is voltage, oxidizing temperature and the time of D.C. regulated power supply, the control porous Al ₂O ₃The aperture of template 3 and hole density.

(3) can adopt chromium plate to make the mask plate 5 that has through hole 6.At first, be slightly larger than in size on the chromium plate of silicon base 1, with glue spreader coating positive electronic bundle resist, rotating speed is got 3500rpm, and covering changeed 20 seconds, went cover to change 20 seconds again.Then, the baking oven of putting into 180 ℃ dried by the fire 30 minutes.Again according to the interconnect location of silicon base 1, be the size and the relative position of interconnection point on silicon base 1 of interconnection point, adopt common computer-aided design (CAD) method plate-making, with Leica VB5 electron beam exposure system chromium plate is exposed again, accelerating voltage is got 50KV, line is got 5nA, and exposure dose is with 800 μ C/cm ²Then, develop, the developer solution proportioning is 1: 3 IPA and a MIBK mixing material, and development temperature is controlled at 19.8 ℃～20.2 ℃, developing time 4 minutes and 20 seconds.At last, use the plasma etching machine, etching gas adopts air to carry CCl ₄, assist gas is hydrogen and nitrogen, the about 24Pa of pressure, and radio-frequency power 350W, etch period is 10 minutes, obtains having the mask plate 5 of through hole 6.The diameter of through hole 6 generally can be 5～10 μ m, and the I of the spacing between the through hole reaches 20 μ m, as Fig. 5, shown in Figure 6.

Mask plate 5 is used to stop catalyst metals, does not need the position that interconnects to prevent that it is planted in.

(4) mask plate 5 that will have a through hole 6 places on the porous alumina formwork 3, and the position that needs to interconnect on through hole 6 and the silicon base 1 is aimed at, and available anchor clamps are fixed, and adopt common little wet impregnation method at 4 bottoms, hole of alumina formwork 3 plantation catalyst metals 7.

After the mask plate 5 that has a through hole 6 fixes with porous alumina formwork 3, put the FeSO of 0.1mol/L into ₄7H ₂Among the O 15 minutes.Then, put it in the quartz boat of the quartzy sedimentation basin of tubular type that twines the resistance heating wire outward, temperature is raised to 500 ℃ in will managing with the speed of about 50 ℃/min, simultaneously, opens the system mechanics pump, takes out intraluminal air.After pressure drops to 10Pa in the quartz ampoule, again the temperature of quartz ampoule is heightened 800 ℃, then feed the hydrogen 1.5 hours of 20mL/min, the pressure in the pipe remains on 150Pa, in through hole 6, Fe catalyst 7 is formed on the bottom in alumina formwork 3 holes 4, as Fig. 7, shown in Figure 8.

Described catalyst metals also can be Co or Ni.

(5) on catalyst metals 7, adopt the method for common chemical vapor deposition to prepare carbon nanotubes 8

Can remove mask plate 5 earlier, will plant the porous alumina formwork 3 of catalyst metals 7 then and put into the outer quartz boat that twines resistance heating wire's the quartzy sedimentation basin of tubular type, chemical vapor deposition CVD process is carried out in quartzy sedimentation basin, is specially, at 700 ℃ of logical 20cm ³The H of/min flow ₂, reducing 115 hours, pressure is 150Pa in the quartzy sedimentation basin; Elevated temperature gradually then is at 750 ℃ of logical 7cm ³The acetylene C of/min flow ₂H ₂And 20cm ³The H of/min flow ₂, the time is 6 hours, pressure is 250Pa in the quartzy sedimentation basin.At this moment, in the through hole 4 of having planted catalyst metals 7, grown CNT (carbon nano-tube).CNT (carbon nano-tube) in the through hole 6 are formed carbon nanotubes 8, the diameter of carbon nanotubes 8 and between spacing decide by the diameter and the position of the through hole 6 of mask plate 5, its length is 800nm.Then, logical N in sedimentation basin ₂, and cool the temperature to room temperature gradually, with its taking-up, as Fig. 9, shown in Figure 10.

Do not wait as the length of carbon nanotubes 8 and the height of template 3, then need carry out common chemico-mechanical polishing (CMP), make that carbon nanotubes 8 and template 3 are contour, obtain smooth surface.

The direction of growth of CNT (carbon nano-tube) is by the direction decision in the hole 4 of porous alumina formwork 3, because of alumina formwork 3 this properties of materials, make the hole 4 of porous alumina formwork 3 have good directivity, can guarantee the surface of the direction of growth of CNT (carbon nano-tube) perpendicular to porous alumina formwork 3.Simultaneously, can control the length of CNT (carbon nano-tube) by the time of control CVD deposition.

Claims (2)

1. the interconnecting method based on CNT (carbon nano-tube) is characterized in that: comprise

(1) on silicon base, deposited by electron beam evaporation one layer thickness is the aluminium film of 20～200nm;

(2) adopt anode oxidation method that the aluminium film preparation is become porous alumina formwork;

(3) according to the interconnection needs of silicon base, adopt exposure, wet development and dry etching, make the mask plate that has through hole;

(4) mask plate that will have a through hole places on the porous alumina formwork, needs the position alignment that interconnects on the through hole of mask plate and the silicon base, adopts the hole bottom plantation catalyst metals of little wet impregnation method at alumina formwork;

(5) on catalyst metals, adopt the method for chemical vapor deposition to prepare carbon nanotubes.

2. nanometer interconnecting method according to claim 1 is characterized in that: catalyst metals is Fe or Co or Ni.

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