JPH0623656A - Analysis sample section polishing method, analysis sample section polishing device, and sample holder for detcting section polishing work terminal - Google Patents

Abstract

PURPOSE:To perform stable grinding regardless of the degree of the skill of an operator. CONSTITUTION:An analysis sample section grinding device comprises a grinding roller 100 to grind an analysis sample 900, a sample stage 200 to which an analysis sample 900 is fixed, and a spring 270 to press the analysis sample 900, fixed to the sample stage 200, against the grinding roller 100 by means of a given pressure. The sample stage 200 is designed to arbitrarily set an angle between the analysis sample 900 fixed to the sample stage 200, and the rotary shaft 110 of the grinding roller 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analytical sample cross-section polishing method, an analytical sample cross-section polishing apparatus and a sample holder for detecting a cross-section polishing end point for obtaining a cross section of an arbitrary portion of an analysis sample such as a semiconductor chip.

[0002]

2. Description of the Related Art A conventional method for obtaining a cross section of an analysis sample such as a semiconductor chip will be described with reference to FIGS. In the following description, the semiconductor chip is referred to as the analysis sample 90.
0, and the minute foreign matter 910 adhering to the surface of this analysis sample 900
I'm trying to get the cross section.

"Cleavage method" In the cleavage method, as shown in FIG. 7 (A), a scratch 990 is made by cutting a glass at a point where an extension line L of a desired cross section of a minute foreign substance 910 intersects with an end,
As shown in (B), a cross section is obtained by cleaving from the scratch 990.

"Dicing method" Fine foreign matter for obtaining cross section
The cross section obtained by cutting the vicinity of 910 with a dyne sig saw 800 is subjected to planar polishing with a polishing film 820 or the like to obtain a cross section of the minute foreign matter 910. For surface polishing, an analysis sample 910 and three dummy 811 (however, only two dummy are shown in the drawing) are used as a polishing table 81.
Then, the polishing table 810 is attached to 0 and the polishing table 810 is moved in the direction of the arrow α. Note that 920 in the drawing indicates a laser marker for displaying the position of the minute foreign substance 910.

[Focused Ion Beam Method] As shown in FIG. 9B, a rectangular hole 960 having a minute foreign substance 910 on one side is formed from a focused ion beam apparatus (hereinafter referred to as "FIB"). The cross section of the minute foreign substance 910 is obtained by opening with the ion beam IB.

"Dicing and FIB combined method" Micro foreign matter
A position as close as possible to 910 is cut by a dicing saw 800 (see FIG. 10B), and a region including this cross section is perforated by FIB to obtain a cross section of the minute foreign substance 910. After cutting with a dicing saw 800, if necessary, the cross-section is flat-polished.

[0007]

However, each of the above-described conventional analytical sample cross-section polishing methods has the following problems. First, since the cleaving method is performed manually, it is very difficult to selectively obtain the cross section of the minute foreign matter 910.

The dicing method can obtain a cross section of the minute foreign substance 910 with a positional accuracy of the order of microns, but chipping (edge portion chipping) occurs at the dicing stage.
It takes a long time to polish the cross section to remove the. In order to reduce the polishing time, it is necessary to perform cutting at a position as close as possible to the minute foreign matter 910, but chipping is likely to damage the minute foreign matter 910, and skill is required.

In the focused ion beam method, the cross section of the minute foreign matter 910 can be obtained with an accuracy of 1 micron or less. However, since the cross section of the minute foreign matter 910 is obtained as a part of the side surface of the hole 960, the cross section is vertical. It cannot be observed from all directions. Excitation source 840 and EDX detector or ion gun 830
Unless the devices are such that the same goes from the same direction to the cross section, this cross section cannot be analyzed (see FIG. 9 (D)).

Further, in the dicing / FIB combination method,
Observation from a direction perpendicular to the cross section 930 becomes possible, and restrictions on the angle between the ion gun 840 and the excitation source and the EDX detector are relaxed during analysis as well as the focused ion beam method. However, the limitation still exists as a matter of degree. That is, as shown in FIG. 10 (J), since the bottom portion of the hole 960 is long, it may interfere with the ion gun 840 or the like. In addition, as shown in FIG.
If the bottom is short, it will not interfere with the ion gun 840.
On the other hand, in the steps of dicing and surface polishing, there are problems of time and skill similar to those of the dicing method. Moreover, F
Since the boring process by IB is added, the time required for the process is further lengthened.

The FIB drilling is carried out by gradually changing the beam current and the beam diameter of the ion beam, and this switching must be carried out by the operator while confirming the cross-sectional shape during processing. Therefore, it greatly depends on the skill level of the operator. Also, the workability is poor.

The present invention was devised in view of the above circumstances, and an object thereof is to provide an analytical sample cross-section polishing apparatus capable of performing stable polishing regardless of the skill of an operator.

[0013]

A method for polishing an analytical sample cross section according to the present invention comprises a first step of polishing an analytical sample cross section at an acute angle with respect to a plane having an analysis point, and after the first step, A second step of performing a drilling process so as to obtain a cross section of the analysis location from the edge of the sample.

Further, the analytical sample cross-section polishing apparatus according to the present invention comprises a polishing roller for polishing the analytical sample, a sample stage on which the analytical sample is fixed, and an analytical sample fixed on the sample stage on the polishing roller. On the other hand, the sample stage is provided with a pressing means for pressing it with a predetermined pressure, and the sample stage can arbitrarily set an angle between the fixed analysis sample and the rotation axis of the polishing roller.

Further, the sample holder for detecting the end point of the cross-section polishing according to the present invention holds the analysis sample to be processed during the boring process by the focused ion beam device and detects the end point of the boring process. A sample holder for end point detection, which is a holder main body electrically connected to an analysis sample,
The holder body is provided with an electrically insulated electrode portion and an ammeter connected to the electrode portion, and it is determined whether or not the electric charge of the ion beam of the focused ion beam device flows into the electrode portion. I detect it with a total.

[0016]

1 is a schematic front view of an analytical sample cross-section polishing apparatus according to an embodiment of the present invention, FIG. 2 is a schematic plan view of this analytical sample cross-section polishing apparatus, and FIG. 3 is this analytical sample cross-section polishing apparatus. FIG. 4 is an explanatory view of a polishing procedure of an analytical sample using the method of FIG. 4, FIG. 4 is an explanatory view showing a procedure of a method of polishing an analytical sample cross section according to one embodiment of the present invention, and FIG. FIG. 6 is a schematic cross-sectional view of a sample holder for detecting a cross-section polishing end point used for polishing an analytical sample by the apparatus, and FIG. 6 is an explanatory diagram showing a procedure of end-point detection by the sample holder for detecting a cross-section polishing end point.

The analytical sample cross-section polishing apparatus according to this embodiment is
A polishing roller 100 for polishing an analysis sample and the analysis sample 900
The sample stage 200 that holds the
The analysis sample 900 fixed to 00 is provided with a pressing unit that presses the polishing sample 100 against the polishing roller 100 with a predetermined pressure,
In the sample stage 200, the angle between the fixed analysis sample 900 and the rotating shaft 110 of the polishing roller 100 can be arbitrarily set.

The analytical sample cross-section polishing apparatus is provided on a base 300. The polishing roller 100, which constitutes such an analytical sample cross-section polishing apparatus, is rotatably supported by a pair of supporting portions 120 with a rotating shaft 110, and the output of the polishing roller drive motor 130 is transmitted via the polishing roller drive belt 140. It is designed to be rotated.

The sample stage 200 comprises a pair of guide rails.
210 makes it possible to move toward and away from the polishing roller 100. A spring 270, which is a pressing means, is bridged between the sample stage 200 and the base 300, and urges the sample stage 200 toward the polishing roller 100. The pulling force of the spring 270 can be changed by changing its length.

On the sample stage 200, an analysis sample 900
Is fixed directly to the sample stage block 220 and the block fixing base 23 to which the sample stage block 220 is fixed.
0, a slide rail 240 for moving the block fixing base 230 in parallel with the rotary shaft 110 of the polishing roller 100, and a slide motor 250.

The sample stage block 220 is formed in a trapezoidal shape with one side being vertical, and a sample fixture 221 for fixing the analysis sample 900 is provided on the side surface thereof.
Two fixing bosses 222a and 222b are provided on the bottom surface of the sample stage block 220.

The block fixing base 230 has a block fixing fulcrum hole (not shown) into which the fixing boss 222a is fitted, and a block fixing hole into which the fixing boss 222b is fitted.
231 have been established. There is only one fulcrum hole for block fixing into which the fixing boss 222a fits, but the fixing boss 222b
A plurality of block fixing holes 231 into which are fitted are arranged on the circumference around the block fixing fulcrum hole. Therefore, the angle of the sample stage block 220, that is, the analysis sample with respect to the polishing roller 100 can be changed depending on which block fixing hole 231 the fixing boss 222b is fitted into.

A polishing liquid supply nozzle 260 connected to a polishing liquid tank (not shown) is attached to the block fixing table 230 so that the polishing liquid is supplied between the polishing roller 100 and the analysis sample 900. ing. Further, the number of rotations of the polishing roller 100 can be adjusted by the knob 310, and the slide speed of the block fixing base 230 can be adjusted by the knob 320 as appropriate.

Next, the procedure for polishing the analytical sample 900 by the analytical sample cross-section polishing apparatus will be described with reference to FIG. A minute foreign substance 910 is located in the center of the analysis sample 900, and four laser markers 920 to be used as marks for polishing are formed around the minute foreign substance 910 (see FIG. 3A). First, the analysis sample 900 is cut with the dicing saw 800 in the vicinity of the minute foreign substance 910 (see FIG. 6B).
Due to this dicing, chipping occurs in the cross section 930 of the analysis sample 900 (see FIG. 6C).

Of the two cut analysis samples 900, the side containing the minute foreign matter 910 is placed on the sample stage block 220 (see FIG. 2).
Fixed). At this time, the cross section 930 of the analysis sample 900
However, the block fixing hole 231 (see FIG. 2) is, of course, selected so as to face the polishing roller 100. At this time, the cross section 930 of the analysis sample 900 is
Select the block fixing holes 231 that form an acute angle with the plane. The sample stage block of analysis sample 900
In principle, the sample is fixed to the sample 220 with the sample fixture 221 (see FIG. 2), but when the analysis sample 900 is minute, it is fixed with a heat-soluble resin such as beeswax.

The cross section 930 of the analysis sample 900 shows the spring 27
It is pressed against the polishing roller 100 with a predetermined pressure by a pulling force of 0. In this way, the polishing roller 100 is rotated at a predetermined rotation speed to perform polishing. During polishing, the polishing liquid is regularly supplied from the polishing liquid supply nozzle 260, and the sample stage 200 is slid along the rotary shaft 110 of the polishing roller 100. This slide prevents uneven wear of the polishing roller 100.

Since the cross section 930 is flat in the initial stage of polishing, the polishing rate at the central portion is high (FIGS. 3D and 3E).
After the cross section 930 is polished along the polishing roller 100, the polishing rate becomes stable (see FIGS. 3F and 3G).

In the state shown in FIG. 3 (F), that is, when the cross section 930 is in contact with the polishing roller 100 and the polishing roller 100 does not reach the minute foreign substance 910, the analysis sample 900 is occasionally removed to perform optical analysis. The polishing time is calculated from the remaining polishing amount with a microscope, and the timer is set so that the polishing is performed for the required polishing time. Note that it is necessary to obtain the polishing conditions based on parameters relating to the polishing speed such as the rotation speed of the polishing roller 100 and the cross-sectional area of the analysis sample 900.

Here, when accuracy on the order of submicrons is required, if the state of FIG.
The analysis sample 900 is removed from the sample stage block 220, and a hole 94 having a side including a minute foreign substance 910 is formed by FIB.
0 is formed (see FIGS. 3H and 3I). by this,
As shown in FIG. 3 (J), a cross section of the minute foreign substance 910 can be obtained.

Further, as shown in FIGS. 4B and 4C, if the cross section 930 of the analysis sample 900 is obliquely polished, the protrusion (shown by the broken line in FIG. 4I) disappears. The direction of the ion gun 840 and EDX detector will be less restricted during analysis. The oblique polishing of the cross section 930 is performed by appropriately selecting the mounting angle of the sample stage block 220 to the block fixing base 230 using the block fixing holes 231.

The hole 940 having a side including the minute foreign substance 910 is F
Formed by IB to obtain a cross section of the minute foreign substance 910 (FIG.
(See (D) to (G)). If the angle between the surface of the analysis sample 900 and the polishing surface is set to be sufficiently small so that the polishing surface reaches below the minute foreign matter 910 when the cross-section 930 is obliquely polished, the FIB drilling process is performed. It is also possible to penetrate all the way to the ground and eliminate any step between the polished surface and the processed cross section of the FIB (see FIGS. 4 (G) and (H)).

When drilling with the FIB,
Sample holder 40 for detecting cross-section polishing end point as shown in FIG.
Use 0. Sample holder 40 for detecting the cross-section polishing end point
0 is the holder body 410, the sample holder 420 for fixing the analysis sample 900 to the holder body 410, and the connecting screw 43 for connecting the sample holder 420 to the holder body 410.
0, an electrode part 450 attached to the notch part 411 of the holder body 410 via an insulator 440, and an ammeter 460 connected to the electrode part 450. The holder body 41
0, the sample holder 420 and the connecting screw 430 are made of a conductive material.

An analysis sample 900 whose cross section 930 is obliquely polished is attached to the holder body 410. At this time, the portion to be perforated, that is, the diagonally polished portion is positioned above the electrode portion 450. Ion beam I from FIB
B is irradiated while raster-scanning the portion to be perforated. At the same time, the electric charge of the ion beam IB flowing into the electrode unit 450 is monitored by the ammeter 460 in synchronism with the raster scan speed of the ion beam IB.

When the ion beam IB hits the analysis sample 900, the charge of the ion beam IB flows from the analysis sample 900 to the ground via the holder main body 410, and when the ion beam IB comes off the analysis sample 900, it passes through the electrode section 450. The electric charge is detected by the ammeter 460 (see FIG. 6 (A)). As the drilling process progresses, the analytical sample 900, which has been thinned by oblique polishing, is scraped off from the end, and the time for the charge of the ion beam IB to flow into the ammeter increases (see FIG. 6B). When the boring process is completed, the electric current into which all the electric charges of the ion beam IB flow into the electrode part 450 becomes constant.
(See FIG. 6 (C)). This state is detected as the processing end point of the drilling process.

From the waveform detected by the ammeter 460, the ammeter
If the ratio of the time when the electric charge flows into the 460 and the time when the electric charge does not flow into the 460, the current processing state can be monitored. Therefore, when it is not necessary to completely penetrate the hole, this ratio is specified according to the required processing level, and the irradiation of the ion beam IB is stopped at the time when the ratio becomes equal, the processing is arbitrary. It will be possible to do.

In the drilling process by FIB,
When processing is performed while changing the beam current or the beam diameter of the ion beam IB stepwise, the processing area is also gradually moved closer to the minute foreign substance 910 in accordance with this, and the end points of each step are detected and the end points are detected. If it is detected, change to the next stage.

[0037]

The analytical sample cross-section polishing method according to the present invention comprises:
A first step of polishing an analysis sample cross section to form an acute angle with respect to a plane having an analysis point, and after the first step, perforation processing is performed so as to obtain a cross section of the analysis point from the edge of the sample. Since it has a second step, since it is polished obliquely with respect to the plane of the analysis sample and then a hole is drilled, the subsequent FI
It is possible to shorten the time required for drilling with B and reduce the probability of damaging minute foreign matter during processing.

The analytical sample cross-section polishing apparatus according to the present invention comprises a polishing roller for polishing the analytical sample, a sample stage on which the analytical sample is fixed, and an analytical sample fixed on the sample stage with respect to the polishing roller. The sample stage is provided with a pressurizing means for pressing with a predetermined pressure, and the angle between the fixed analysis sample and the rotation axis of the polishing roller can be arbitrarily set. Since the conditions can be quantified, stable polishing can be performed regardless of the skill of the operator.

The analytical sample cross-section polishing apparatus does not require a precise polishing end point detection mechanism or the like. Further, the polishing time can be shortened as compared with the conventional flat polishing.
Therefore, it is not necessary to bring the cutting in the pre-polishing step close to the minute foreign matter to the utmost limit, and the probability of damaging the minute foreign matter in the cutting step is reduced.

On the other hand, the sample holder for detecting the end point of the cross-section polishing according to the present invention detects the end point of the boring process by holding the analysis sample to be machined during the boring process by the focused ion beam device. , A holder main body electrically connected to an analysis sample, an electrode section electrically insulated from the holder main body, and an ammeter connected to the electrode section. Since the ammeter detects whether or not the electric charge of the beam is flowing into the electrode portion, the end point can be automatically detected. Therefore, F
It becomes possible to improve the workability of IB processing and shorten the processing time.

[Brief description of drawings]

FIG. 1 is a schematic front view of an analytical sample cross-section polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of this analytical sample cross-section polishing apparatus.

FIG. 3 is an explanatory view of a polishing procedure for an analysis sample using this analysis sample cross-section polishing apparatus.

FIG. 4 is an explanatory diagram showing a procedure of an analytical sample cross-section polishing method according to an example of the present invention.

FIG. 5 is a schematic cross-sectional view of a sample holder for detecting a cross-section polishing end point, which is used for polishing an analysis sample by an analysis sample cross-section polishing apparatus according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a procedure of end point detection by the sample holder for detecting the end point of the cross-section polishing process.

FIG. 7 is an explanatory diagram of a cleavage method which is one of conventional methods for polishing a cross section of an analytical sample.

FIG. 8 is an explanatory diagram of a dicing method which is one of conventional methods for polishing a cross section of an analytical sample.

FIG. 9 is an explanatory diagram of a focused ion beam method which is one of conventional methods for polishing a cross section of an analytical sample.

FIG. 10 is an explanatory diagram of a method of combined use of dicing and FIB, which is one of conventional analysis sample cross-section polishing methods.

[Explanation of symbols]

 100 Polishing roller 110 Rotation axis 200 Sample stage 450 Electrode 900 Analysis sample

Claims (3)

[Claims] 1. A first step of polishing a cross section of an analysis sample to form an acute angle with respect to a plane having an analysis point, and after the first step, obtaining a cross section of the analysis point from an edge of the sample. And a second step of performing a boring process. 2. A polishing roller for polishing an analysis sample, a sample stage on which the analysis sample is fixed, and a pressing unit for pressing the analysis sample fixed on the sample stage against the polishing roller at a predetermined pressure. The analytical sample cross-section polishing apparatus is characterized in that the sample stage can arbitrarily set an angle between the fixed analytical sample and the rotation axis of the polishing roller. 3. A cross-section polishing end point detecting sample holder that holds an analysis sample to be processed during hole forming by a focused ion beam device and detects an end point of hole forming, and is electrically connected to the analysis sample. And a holder main body, an electrode section electrically insulated from the holder main body, and an ammeter connected to the electrode section, and the electric charge of the ion beam of the focused ion beam apparatus is applied to the electrode section. A sample holder for detecting the end point of cross-section polishing, which is characterized by detecting whether it is flowing or not with an ammeter.