CN105136539B

CN105136539B - A method of preparing TEM chip sample

Info

Publication number: CN105136539B
Application number: CN201510532705.2A
Authority: CN
Inventors: 陈强
Original assignee: Shanghai Huali Microelectronics Corp
Current assignee: Shanghai Huali Microelectronics Corp
Priority date: 2015-08-26
Filing date: 2015-08-26
Publication date: 2019-05-03
Anticipated expiration: 2035-08-26
Also published as: CN105136539A

Abstract

The present invention provides a kind of method for preparing TEM chip sample, the chip containing metallic circuit is formed at least one surface for exposing the metallic circuit under focused ion beam cutting, in the surface deposited carbon layer, so that carbon-coating covers the metallic circuit.Chip sample preparation method provided by the invention makes in the surface deposited carbon layer for exposing metallic circuit; the metallic circuit for protecting surface to expose using carbon-coating; metallic circuit is made not contact outside air in this way; to prevent by outside air oxidation corrosion; even if covering carbon-coating on surface simultaneously; also observation of the sample in transmission electron microscope is had no effect on, therefore improves the success rate of sample preparation.

Description

A method of preparing TEM chip sample

Technical field

The present invention relates to the field of transmission electron microscope observing chip sample, in particular to a kind of side for preparing TEM chip sample Method.

Background technique

Transmission electron microscope (Transmission Electron Microscope, abbreviation TEM) referred to as transmits electricity Mirror, be on accelerated and aggregation e-beam projection to very thin sample, electronics and the ion collision in sample and change Direction, to generate solid angle scattering, the size of angle of scattering is related to the density of sample, thickness, therefore can form light and shade not Same image, image will be shown on image device (such as fluorescent screen, film or photosensitive coupling component) after amplification, focusing Come.Nowadays transmission electron microscope suffers from extremely wide and more and more important answer in the every field including Integrated circuit analysis With, and FIB (Focused Ion beam, focused ion beam) sample preparation is then semiconductor field TEM sample preparation the most main Means.

In current chip fabrication techniques, the material for making metallic circuit uses aluminium, nickel, copper etc., in order to improve gold The intensity for belonging to route, can also plate the metals such as gold, silver on metallic circuit in the subsequent process, to encapsulate a chip, often need To pass through multiple working procedure, in this multiple working procedure, the metallic circuit of formation and the other parts of chip are often because of environment Influence and change, these variations may will affect the reliability of chip, or even the metallic circuit formed can produce fracture, Cause entire chip failure, it is therefore desirable to be analyzed the chip of these failures, especially need to observe metal wire in chip The failure conditions on road.

At present when containing the chip of metallic circuit using transmission electron microscope observing, if necessary to observe the growth of metallic circuit Situation please refers to Fig. 1 and Fig. 2, and chip 1 is first usually cut into a sample strip 3, this sample from centre with focused ion beam There are the exposing of metallic circuit 2 in 3 two sides of product piece.In current chip fabrication techniques, 2 material of metallic circuit of subsequent growth is usual For copper, and copper exposure is easily oxidized in air, and moreover, copper ion is easily spread, and is made around metallic circuit 2 The part two sides causing a degree of variation, therefore cause sample strip 3 be easy to change original growth complexion so that seeing It examines and makes a fault.

Therefore in view of the foregoing drawbacks, it is necessary to above-mentioned TEM chip sample preparation method be improved, sample preparation success is improved Rate.

Summary of the invention

The present invention provides a kind of method for preparing TEM chip sample, in view of the above-mentioned problems, being cut into exposing metallic circuit Surface after, deposited carbon layer, protects metallic circuit not by outside air oxidation corrosion, while transmiting so on a surface Carbon-coating also has no effect on observation in Electronic Speculum, therefore improves the success rate of sample preparation.

In order to achieve the above objectives, the present invention provides a kind of method for preparing TEM chip sample, by the core containing metallic circuit Piece forms at least one surface for exposing the metallic circuit under focused ion beam cutting, in the surface deposited carbon layer, makes Carbon-coating is obtained to cover the metallic circuit.

Preferably, the following steps are included:

Step 1: the chip containing metallic circuit is provided；

Step 2: the chip containing metallic circuit is cut using the focused ion beam, so that described contain There is the chip of metallic circuit to form at least one described surface, exposes the metallic circuit on the surface；

Step 3: the reagent for being used to form carbon-coating will be packed into the device for being used to emit the focused ion beam, and to step The surface emitting electron beam and the reagent in rapid two are bombarded, on said surface deposited carbon layer；

Step 4: removal is cut into part untreated on the chip containing metallic circuit, chip sample is made Product piece.

Preferably, forming four surfaces in step 2.

Preferably, the reagent for being used to form carbon-coating in step 3 is C₁₀H₈Gas.

Preferably, the time bombarded in step 3 is 20 seconds~30 seconds.

Preferably, for emitting the device of the focused ion beam as electron gun transmitting, the electron gun in step 3 The current strength of transmitting is 11nA.

Preferably, acute angle formed by the direction of the launch of the electron beam in the electron gun and the surface is 52 °.

Preferably, deposited carbon layer is to carry out under vacuum conditions on said surface.

Preferably, the carbon layers having thicknesses deposited on said surface are 10nm~50nm.

Preferably, the material of the metallic circuit is copper.

Compared with prior art, the beneficial effects of the present invention are: the present invention provides a kind of side for preparing TEM chip sample Chip containing metallic circuit is formed at least one surface for exposing the metallic circuit under focused ion beam cutting by method, In the surface deposited carbon layer, so that carbon-coating covers the metallic circuit.Chip sample preparation method provided by the invention makes Obtain the metallic circuit for protecting surface to expose using carbon-coating in the surface deposited carbon layer for exposing metallic circuit, so that metal Route will not contact outside air, to prevent by outside air oxidation corrosion, while even if carbon-coating be covered on surface, also simultaneously Observation of the sample in transmission electron microscope is not influenced, therefore improves the success rate of sample preparation.

Detailed description of the invention

Fig. 1 is untreated chip sample cross-sectional view in the prior art；

Fig. 2 is in the prior art using the sample strip cross-sectional view formed after focused ion beam cutting；

Fig. 3 is that chip sample uses the cross-sectional view after focused ion beam cutting in the present invention；

Fig. 4 is the cross-sectional view in the present invention in chip sample side deposited carbon layer；

Fig. 5 is the cross-sectional view that the sample strip formed after unprocessed portion is cut in the present invention；

Fig. 6 is the flow chart for the method that the present invention prepares TEM chip sample.

Prior art illustration: 1- chip, 2- metallic circuit, 3- sample strip；

The present invention diagram: 10- chip, 11- first surface, 12- second surface, 13- third surface, the 4th surface 14-, 20- metallic circuit, 30- focused ion beam, 40- electron beam, 50-C₁₀H₈Gas, 60- sample strip, 70- carbon-coating, 80- excess portion Divide, 90- chip sample piece.

Specific embodiment

In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, with reference to the accompanying drawing to the present invention Specific embodiment be described in detail.

Embodiment one

It please refers to Fig. 6, and combines Fig. 3 to Fig. 5, in order to achieve the above objectives, the present invention, which provides, a kind of prepares TEM chip sample Method, comprising the following steps:

Step 1: the chip 10 containing metallic circuit 20 is provided；

Step 2: referring to figure 3., cutting the chip 10 containing metallic circuit 20 using focused ion beam 30, compared with Goodly, the ion gun current strength for being used for transmitting focusing ion beam 30 is adjusted to 100pA~7000pA, uses focused ion beam 30 are cut into two grooves in 10 middle section of chip, expose the intermediate sample strip 60 observed, described two grooves Inner wall sequentially form first surface 11, second surface 12, third surface 13, the 4th surface 14, this four surfaces are parallel to each other, All there is the exposing of metallic circuit 20 on second surface 12, third surface 13, generally, the material of these metallic circuits 20 is copper, Placement is oxidized easily corrosion in air.

Step 3: referring to figure 4., also have in the device (not shown) where the ion gun for transmitting focusing ion beam 30 There is electron gun, used in electron gun closes ion gun in launching electronics beam 40, opens electron gun, under vacuum conditions, is directed at the second table Face 12 and 13 launching electronics beam 40 of third surface bombard, and the acute angle theta that electron gun and second surface 12 are formed is 52 °, by electron beam 40 emission current intensity is set as 11nA, while being furnished with gas injection system in the system where electron gun, gas injection System discharges C to second surface 12 and third surface 13₁₀H₈Gas 50, positioned at the gas of second surface 12 and third surface 13 Molecular link is broken under the scanning bombardment of electron beam 40, is formd carbon dust, is fallen on second surface 12 and third surface 13, It is gradually deposited into carbon-coating 70, after electron beam 40 emits 20 seconds~30 seconds, electron gun and gas injection system is closed, stops carbon-coating 70 deposition, the carbon-coating 70 obtained at this time with a thickness of 10nm~50nm, so that metallic circuit 20 will not contact extraneous sky Gas, to prevent metallic circuit 20 by outside air oxidation corrosion.In addition, in second surface 12 and third surface 13 due to surface The blocking of carbon-coating 70 can alleviate the copper ion in metallic circuit 20 to neighbouring diffusion, therefore it is attached to slow down metallic circuit 20 It is close partially due to copper ion diffusion and occur rotten.

Step 4: referring to figure 5., redundance 80 is cut and is removed, chip sample piece 90 is made.

Manufactured chip sample piece 90 is put into transmission electron microscope and is observed, since transmission electron microscope is when observing sample, The pattern of sample is to penetrate sample for observing the incident beam of sample by transmitting to obtain, and incident beam equally may be used To penetrate carbon-coating 70, so that sample topography is presented, and since the carbon atom ordinal number in carbon-coating 70 is smaller, for Influence (such as scatter) very little of incident beam so that the pattern of the chip sample piece 90 showed with without being in when carbon-coating 70 Existing consistent appearance, therefore the carbon-coating 70 being located on second surface 12 and third surface 13 has no effect on the observation of transmission electron microscope.

Obviously, those skilled in the art can carry out various modification and variations without departing from spirit of the invention to invention And range.If these modifications and changes of the present invention is within the scope of the claims of the present invention and its equivalent technology, then The invention is also intended to include including these modification and variations.

Claims

1. a kind of method for preparing TEM chip sample, which comprises the following steps:

Step 1: the chip containing metallic circuit is provided；

Step 2: the chip containing metallic circuit is carried out using focused ion beam to be cut into two grooves, so that described contain The chip of metallic circuit forms at least one surface, and the metallic circuit, the inner wall of described two grooves are exposed on the surface First surface, second surface, third surface, the 4th surface are sequentially formed, this four surfaces are parallel to each other, in second surface, All there is metallic circuit exposing on three surfaces；

Step 3: the reagent for being used to form carbon-coating will be packed into the device for being used to emit the focused ion beam, and to step 2 In the second surface and third surface emitting electron beam and the reagent bombarded, deposited carbon layer on said surface, Deposited carbon layer is to carry out under vacuum conditions on said surface, and the device in step 3 for emitting the focused ion beam is Electron gun, the current strength of electron gun transmitting are 11nA, the direction of the launch of the electron beam in the electron gun respectively with institute Stating acute angle formed by second surface and third surface is 52 °, and the time of bombardment is 20 seconds~30 seconds, and the carbon layers having thicknesses of deposition are 10nm~50nm, so that metallic circuit will not contact outside air, to prevent metallic circuit by outside air oxidation corrosion；

Step 4: removal is cut into part untreated on the chip containing metallic circuit, chip sample piece is made.

2. the method for preparing TEM chip sample as described in claim 1, which is characterized in that be used to form carbon-coating in step 3 Reagent be C₁₀H₈Gas.

3. the method for preparing TEM chip sample as described in claim 1, which is characterized in that the material of the metallic circuit is Copper.