CN102569261B

CN102569261B - Structure and method for testing heat radiating characteristic of nanoscale device

Info

Publication number: CN102569261B
Application number: CN201210005993.2A
Authority: CN
Inventors: 黄如; 林增明; 王润声; 邹积彬; 孙帅
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2012-01-10
Filing date: 2012-01-10
Publication date: 2014-02-19
Anticipated expiration: 2032-01-10
Also published as: CN102569261A

Abstract

The invention discloses a structure and a method for testing a heat radiating characteristic of a nanoscale device. The structure comprises a source (1), a drain (2) and a gate (3), wherein a suspended nanowire (5) is arranged between the source (1) and the drain (2); and an insulating layer (6) is arranged between the gate (3) and the drain (2). A ring fence structure is used, and one end of the gate (3) is connected with one wiring board (4). The method comprises the following steps of: taking points on the nanowire from a source end to a gate end at certain intervals, sequentially heating the points on the nanowire by using high power laser, calculating temperature differences between each point and the source end and between each point and a drain end by using the measured peak shift of the Raman spectrum of each point, and solving the temperature of each point; calculating the total thermal resistance RTHG of the route of the gate and the thermal resistance RTHD of the nanowire from the gate end to the drain end; and comparing the RTHG with the RTHD, and finding out a main heat radiating route. The heat radiating way of the nanoscale device can be improved according to a testing result, so that the characteristic of the device can be improved.

Description

A kind of test structure of nanoscale devices heat dissipation characteristics and method of testing

Technical field

The present invention relates to a kind of method of testing of heat dissipation characteristics, relate in particular to a kind of method of testing of nanoscale wire device heat dissipation characteristics.By designing a kind of simple test structure, and utilize existing technology, thereby realize, the heat dissipation characteristics of nanoscale devices is studied.

Background technology

Along with CMOS(Complementary Metal Oxide Semiconductor) dwindling of device feature size and improving constantly of integration density, the power consumption of circuit and the dissipation of heat become a question of common concern.When device feature size enters sub-micron, deep-submicron field, the integration density of circuit is greatly improved, and the rising that the power consumption of sharp increase is simultaneously brought chip temperature, can make device performance degeneration, reliably working to circuit impacts, and even may make whole circuit malfunction.So nearly decades, people give and increasing concern the research of the thermal characteristics test of material, comprise the research of single nano-wire thermal conductivity, the research of thermal conductivity of thin film, and the research of whole device thermal conductivity.Many method of testings have in succession been there are, yet arrive certain degree when device size is little, the research method of traditional thermal characteristics and tester can not meet testing requirement gradually, this has brought very large challenge to the research of device thermal characteristics, designs a kind of simple and effective method of testing and is necessary.

In recent years, in succession there are to many methods in the test of material thermal characteristics, for example, steady-state method, film micron calorimeter method, Micro-Rpectra method, the micro element detector method that suspends, thermography method, thermoelectricity mirror method and 3 ω technology etc.Micro-Rpectra method wherein, it is the Raman scattering effect of finding based on India scientist C.V. Raman (Raman), and the research method of development a kind of material behavior out, be applied in early days molecular structure research, because every kind of material has oneself Raman peaks, and Raman peaks can produce peak and move with the difference of temperature, so this character of increasing thermal recovery Raman spectrum is carried out the thermal characteristics of research material in recent years, in succession there is the test of single nano-wire material thermal conductivity, the test of layer material thermal conductivity, and full-fledged gradually.And along with the development of laser technology, the hot spot of getting on object is more and more less, makes Raman spectroscopy be applied to gradually small-size materials.

Summary of the invention

The object of the invention is in conjunction with laser Raman spectrum method, by utilizing a kind of simple structure, realize the heat dissipation characteristics of nanoscale devices is studied.

Technical scheme provided by the invention is as follows:

A kind of test structure of nanoscale devices heat dissipation characteristics (Fig. 1), comprises source 1, leaks 2, grid 3 three parts, it is characterized in that, wherein source 1 and leak 2 between have a unsettled nano wire 5; Grid 3 and leak 2 between have insulating barrier 6; What described structure adopted is to enclose grid structure, and grid 3 are surrounded nano wire 5, and one end of grid 3 is connected with a terminal block 4.

Described test structure, is characterized in that, described test structure be take SOI as substrate.

Described test structure, is characterized in that, described insulating barrier 6 is insulation material layer or air.

A method of testing for nanoscale devices heat dissipation characteristics, is characterized in that, comprises the steps:

1) make test structure recited above;

2) by source, started until grid, every a segment distance D, on nano wire, get a point, adopt high power laser light successively to each some heating on nano wire, when whole system enters stable state, (when the temperature of each several part no longer changes) collects the Raman spectrum of each point;

3) peak of the Raman spectrum by each measured point moves, and calculates the temperature difference between each point and source and drain, and then tries to achieve the temperature of each point;

4) calculate the total thermal resistance R by this paths of grid _tHGand the nano wire thermal resistance R between from grid to drain terminal _tHD;

5) compare R _tHGand R _tHDsize, find out main heat dissipation path.According to test result, can improve the heat radiation approach of nanoscale devices, thus the characteristic of raising device.

Described method of testing, is characterized in that, test structure is made on SOI substrate described in step 1).

Described method of testing, is characterized in that step 2) the described step of heated at various points of giving carries out at ambient temperature.

Described method of testing, is characterized in that step 2) described high power laser light is that the hot spot power of getting on nano wire is the laser of milliwatt magnitude.

Described method of testing, is characterized in that step 2) described distance B=0.5um.

Described method of testing, is characterized in that, described step 4) is put the distance X substitution formula apart from source and nano wire junction by the temperature T of each point of gained and this:

T-T ₀=P[R _tH1(R _tH2+ R _tH3)]/(R _tH1+ R _tH2+ R _tH3)=P (MX ²+ NX) (formula 1)

R _TH3=R _THG//R _THD

T wherein ₀for room temperature, " // " is symbol in parallel, R _tH1the point of getting to for laser is to the nano wire thermal resistance between source, R _tH2the point of getting to for laser is to the nano wire thermal resistance between grid, R _tH3for the heat radiation approach that formed by grid and and the total thermal resistance of heat radiation approach that formed by source, P is that nano wire absorbs total amount of heat, X gets to laser spot center on nano wire to the distance of source, M, N are coefficient, M=-1/[KA (l-a-h)+K ²a ²r _tH3], N=[(l-a-h)/K ²a ²+ R _tH3]/[(l-a-h)/KA+R _tH3], for length, be L, the even line that cross-sectional area is A, thermal resistance R _tH=L/KA, wherein K is nano wire thermal conductivity, so R _tH1=X/KA, R _tH2=(l-a-h-X)/KA, l is nano wire total length, a is that grid are long, h be grid to the distance of drain terminal, the distance substitution formula 1 by the temperature of the each point recording and each point apart from source, obtains P and R _tH3value; By nano wire thermal resistance formula, calculate R again _tHD, and then calculate R _tHG.

Described method of testing, is characterized in that, in step 5), if R _tHG> > R _tHD, illustrate that source is main heat dissipation path, else if R _tHG< < R _tHD, illustrate that grid are main heat dissipation path, if R _tHGwith R _tHDquite, illustrate that the ability that they dispel the heat is suitable.

Beneficial effect of the present invention:

The invention provides a kind of simple and effective heat dissipation characteristics method of testing, by a kind of simple test structure, realized nanoscale devices heat dissipation characteristics has been tested, choosing of the design of nanoscale devices radiator structure and material provided to direct directive function, and brought reference and help for the design of thermal resistance network and device architecture.

Accompanying drawing explanation

Fig. 1 test structure figure.Wherein: source 1; Leak 2; Grid 3; Terminal block 4; Nano wire 5; Insulating barrier 6;

Fig. 2 is the equivalent thermal resistance network model figure of test structure.

Embodiment

The present invention is described in detail with specific embodiment by reference to the accompanying drawings below, provides the micro-Raman spectroscopy of a kind of combination, by utilizing a kind of test structure to realize, nanoscale devices heat dissipation characteristics tested.

(1) make test structure

1, substrate is SOI(Silicon-On-Insulator) material, first by substrate upper strata silicon attenuate, residue 200nm, utilizes photoetching technique to carve the Fin bar between the leakage of ,Lou He source, source in substrate silicon layer;

2, oxidation Fin bar, and with utilizing chemical reagent that silica is floated, in structure, form unsettled nano wire;

3, source is leaked and protected, slight oxidation forms grid oxygen and insulating barrier;

4, the polysilicon that deposition thickness is 250nm, electron beam lithography forms grid and line connection board, thereby forms test structure;

(2) while testing, by source, started, along nano wire, every 0.5um, get a point, adopt high power (the hot spot power of getting on nano wire is milliwatt magnitude) laser successively respectively to each some heating on nano wire, when whole system enters stable state, both the temperature of each several part no longer changed the Raman spectrum of collecting constantly each point;

(3) position of the Raman peaks of the Raman spectrum of each point relatively, moves by recording the Raman peaks of each point, calculates the temperature difference between each point and source drain terminal and (source, leaks the temperature of terminal block in addition and think room temperature T ₀);

The thermal resistance equivalent network model of test structure as shown in Figure 2, set up number axis, take source and nano wire junction is initial point, along nano wire, pointing to drain terminal is positive direction, in the time of on the laser nano wire that to get to apart from initial point be X, nano wire can absorb the heat of a part of laser, thereby the nano wire portion temperature of being got to by laser is raise, when whole system enters stable state, can in test structure, form three stable heat radiation approach, the heat dissipation path being formed by source, the heat radiation approach being formed by grid and terminal block and the heat radiation approach being formed by leakage, suppose that the hot-fluid dispelling the heat by source path is P ₁, by total hot-fluid of grid and drain terminal, be P ₂, what nano wire absorbed must heat be P,

P=P ₁+P ₂

Therefore the temperature T for laser facula heating place nano wire just can be expressed as:

T-T ₀=P ₁R _TH1=P ₂(R _TH2+R _TH3)

R wherein _tH1the point of getting to for laser is to the nano wire thermal resistance between source, R _tH2the point of getting to for laser is to the nano wire thermal resistance between grid, R _tH3for the heat radiation approach that formed by grid and and the total thermal resistance of heat radiation approach that formed by source

By above-mentioned two formula, obtained:

T-T ₀=P[R _TH1(R _TH2+R _TH3)]/(R _TH1+R _TH2+R _TH3)

For length, be L, the even line that cross-sectional area is A, thermal resistance R _tH=L/KA, wherein K is nano wire thermal conductivity, so R _tH1=X/KA, R _tH2=(l-a-h-X)/KA, l for nano wire total length in this experiment, a be that grid are long, h is that thickness of insulating layer also can be described as grid to the distance of drain terminal, substitution above formula obtains:

T-T ₀=P(MX ²+NX)

Wherein, M=-1/[KA (l-a-h)+K ²a ²r _tH3], N=[(l-a-h)/K ²a ²+ R _tH3]/[(l-a-h)/KA+R _tH3], by the position of the temperature of the each point recording in step 3 and each point (being that each point is apart from the distance of source) substitution above formula, because above-mentioned formula only has two unknown number P and R _tH3so, can obtain P and R _tH3value;

And R _tH3can be equal to the processing of resistance, regard that grid heat radiation approach is in parallel with source heat-dissipating approach as, grid heat radiation approach thermal resistance can be used R _tHGrepresent source heat-dissipating approach thermal resistance R _tHDrepresent, that is:

R _TH3=R _THG//R _THD

And R _tHDcan think the nano wire thermal resistance of grid between arriving leakage, i.e. R _tHD=(h+a)/KA, so can obtain R _tHG;

(4) compare the R of gained _tHGand R _tHDvalue, if R _tHG> > R _tHDillustrate that source is main heat dissipation path, if contrary R _tHG< < R _tHDillustrate that grid are main heat dissipation path, if R _tHGwith R _tHDquite, illustrate that the ability that they dispel the heat is suitable, according to experimental result, can improve the heat radiation approach of nanoscale devices, thereby improve the characteristic of device;

As an embodiment, in the test structure that above-mentioned steps () forms, the total length of nano wire is l=10um, and grid are long is a=200nm, thickness of insulating layer h=5nm.

Claims

1. a method of testing for nanoscale devices heat dissipation characteristics, is characterized in that, comprises the steps:

1) make test structure, described test structure comprises source (1), leaks (2), grid (3) three parts, wherein between source (1) and leakage (2), has a unsettled nano wire (5); Between grid (3) and leakage (2), there is insulating barrier (6); What described structure adopted is to enclose grid structure, and grid (3) are surrounded nano wire (5), and one end of grid (3) is connected with a terminal block (4);

2) by source, started until grid are got a point every a segment distance D on nano wire, adopt high power laser light successively to each some heating on nano wire, when whole system enters stable state, collect the Raman spectrum of each point;

5) compare R _tHGand R _tHDsize, find out main heat dissipation path;

Described step 4), the temperature T of each point of gained and this are put to the distance X substitution formula apart from source and nano wire junction:

R _TH3=R _THG//R _THD

T wherein ₀for room temperature, " // " is symbol in parallel, R _tH1the point of getting to for laser is to the nano wire thermal resistance between source, R _tH2the point of getting to for laser is to the nano wire thermal resistance between grid, R _tH3for the heat radiation approach being comprised of grid and the total thermal resistance of heat radiation approach being comprised of source, P is that nano wire absorbs total amount of heat, and X gets to laser spot center on nano wire to the distance of source, and M, N are coefficient, M=-1/[KA (l-a-h)+K ²a ²r _tH3], N=[(l-a-h)/K ²a ²+ R _tH3]/[(l-a-h)/KA+R _tH3], for length, be L, the even line that cross-sectional area is A, thermal resistance R _tH=L/KA, wherein K is nano wire thermal conductivity, so R _tH1=X/KA, R _tH2=(l-a-h-X)/KA, l is nano wire total length, a is that grid are long, h be grid to the distance of drain terminal, the distance substitution formula 1 by the temperature of the each point recording and each point apart from source, obtains P and R _tH3value; By nano wire thermal resistance formula, calculate R again _tHD, and then calculate R _tHG.

2. method of testing as claimed in claim 1, is characterized in that, test structure is made on SOI substrate described in step 1).

3. method of testing as claimed in claim 1, is characterized in that step 2) the described step of heated at various points of giving carries out at ambient temperature.

4. method of testing as claimed in claim 1, is characterized in that step 2) described high power laser light is that the hot spot power of getting on nano wire is the laser of milliwatt magnitude.

5. method of testing as claimed in claim 1, is characterized in that step 2) described distance B=0.5um.

6. method of testing as claimed in claim 1, is characterized in that, in step 5), if R _tHG> > R _tHD, illustrate that source is main heat dissipation path, else if R _tHG< < R _tHD, illustrate that grid are main heat dissipation path, if R _tHGwith R _tHDquite, illustrate that the ability that they dispel the heat is suitable.