JPH08162517A - Sample holder - Google Patents

Abstract

PURPOSE: To obtain a sample holder which can perform sputter-etching without causing element breakage or short circuit, in a semiconductor device mounted in a package. CONSTITUTION: A conductive base 9 has a hole 10 to mount a semiconductor device 10 to be packaged, and therein a metallic mesh 15 which is put at the same potential as the base 9 by metallically contacting with an electrode 6, is installed, and the mesh may be removed by taking away the cover 16. Moreover, an insulating base cover 11 provided with an opening with a dimension approximately equal to or smaller than that of the semiconductor device 2 by a variable aperture is mounted on the topside of the base 9, and a bonding wire 4 and a pad 5 are hidden behind the opening 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holder for mounting and fixing a semiconductor device as a sample and performing a sputter removal process by a focused ion beam processing device or a film forming process by a laser CVD device, and more particularly, The present invention relates to a sample holder in which a sample mounted in a package is not damaged or contaminated by the above processes.

[0002]

2. Description of the Related Art In recent semiconductor devices, the degree of integration is remarkably high, and the number of wiring layers is also increasing. For this reason,
The semiconductor device in the development process does not always operate as designed, and the development has been advanced by repeating the remanufacturing from the wiring layer using a partially changed photomask. Therefore, it took a long time to reach completion.

On the other hand, recently, a semiconductor device having a malfunction is directly subjected to a sputtering process using a focused ion beam to cut an arbitrary wiring in the semiconductor device,
A technique has been put into practical use in which a cause of a defect or a place is identified or repaired by connecting arbitrary wirings by a film forming process using laser CVD. As a result, the development period of the semiconductor device can be significantly shortened.

Japanese Unexamined Patent Publication No. 63-164240 (Prior Art 1) discloses a technique for correcting a semiconductor device using focused ion beam processing and laser CVD. The correction process in this publication consists of the following six steps, and the first to fifth steps described below are performed without exposing the semiconductor device to the atmosphere.

1) Cleaning: The contaminants such as water and organic substances adhering to the surface of the semiconductor device are removed by sputter etching of Ar ions.

2) Window opening: The passivation film on the wiring to be connected to the wiring is removed by irradiation with a focused ion beam to expose the wiring.

3) Buffer film formation: A buffer film made of Cr or the like is formed on the surface of the semiconductor device and on the wiring exposed in the window opening process by sputter deposition using a target such as Cr.

4) Filling: The wiring exposed in the second step is irradiated with a laser beam in a CVD material gas atmosphere such as Mo (CO) ₆ to deposit a metal such as Mo from the CVD material gas by thermal decomposition. Fill.

5) Wiring formation: In the same manner as the filling, the laser light is scanned in the CVD material gas atmosphere in the filled section,
The metal film is linearly formed.

6) Removal of buffer film: The buffer film formed on the surface of the semiconductor device other than under the wiring formed in the fifth step is removed by sputter etching of Ar ions.

Through the above steps, the low resistance of the wiring connection and the high reliability of the correction are achieved.

A sample holder suitable for the conventional example is disclosed in Japanese Patent Laid-Open No. 4-177856 (Prior Art 2). This sample holder uses a semiconductor device in a chip state as a sample, and the sample can be held by a fixed member and a movable member provided on the sample table. The movable member has a structure that can be easily moved in one direction and does not cause the sample to float, and the sample is pressed against the fixed member side with a weak force of the minimum necessary amount. In the cleaning process or the buffer film removal process, the fixed member and the movable member are made of an insulating material so as to eliminate the unevenness of the discharge at the time of the sputtering and etching of the Ar ions due to the high frequency discharge, so that the structure has no protrusion. ing. With this configuration, the sample (semiconductor chip) can be fixed to a predetermined position with a constant force with good reproducibility and without chipping. Further, it is possible to ensure the uniformity of etching due to discharge.

Further, a method of selectively treating only a specific portion in the etching treatment step is disclosed in Japanese Patent Laid-Open No. 6-128763 (Prior Art 3). This is a contamination prevention device in a reactive ion etching device, and covers a place other than the sample with a cover so that a substance scraped by etching the place other than the sample does not contaminate the sample surface. . An opening having a certain size is provided at the center of the cover, and a mask having the opening is detachably attached to the opening. By using this apparatus for etching the sample, only the opening can be selectively processed. Further, by changing the size of the opening of the mask, it is possible to flexibly deal with various samples having different shapes and sizes.

[0014]

In the sample holders of the prior arts 1 and 2, a chip obtained by scribing a wafer on which wiring layers and insulating layers are laminated is used as a sample. However, in a typical semiconductor device, the chip is DIP (Dual In Line Pack).
age), QFP (Quad Flat Package), PGA (PinGrid Ar)
It is a product that is attached to various packages such as ray) with thermosetting resin, etc., connected to the chip and package with bonding wires, etc., and further sealed.

At the time of product development, a semiconductor device in a chip state can be used for defect analysis and repair. However, when a defect occurs after packaging, analysis and repair must be performed in the package state.

When the wiring of the package-mounted semiconductor device is corrected by using the conventional sample holder, there are the following problems.

1) When all the electrodes of the package are electrically separated from the sample holder when the sample is simply clamped and fixed, at the time of cleaning by sputtering / etching to secure the adhesion of the wiring by laser CVD, The charge is accumulated on the surface of the sample, which causes a decrease in the etch rate. Also, when some electrodes of the package are in electrical contact with the sample holder, when cleaning by sputter etching,
Due to the potential difference between the electrodes, discharge may occur between the internal elements, and the elements may be destroyed.

2) A cross-sectional view of the package-mounted sample is shown in FIG. 1. The Au film 3 and the bonding wire 4 exposed on the surface of the package 1 on which the semiconductor device is attached are made of an inert gas (as shown in FIG. 2). For example, sputtering with Ar, He) 7
It may be sputtered by etching and may adhere to the side wall of the semiconductor device 2 or the package or to the shadow of the wire or the like to cause a short circuit between the wire bonding pads 5 of the semiconductor device 2 or the package 1.

Further, in the cover according to the prior art 3, the opening portion is changed by using a detachable mask so that it is possible to handle samples having different sizes and shapes.
However, with a cover for a moving object such as a sample holder,
The mask must be secured so that it does not come off. Therefore, it is preferable that the opening can be changed directly on the cover instead of being removable.

An object of the present invention is to provide a sample holder which can surely correct wiring in a package-mounted semiconductor device by a sputtering / etching process without causing element breakdown or short circuit.

[0021]

In order to achieve the above object, the present invention has made all electrodes of the package substantially the same potential as the holder as a solution to the first problem. Therefore, a conductive fixing member that matches the thickness and pitch of the electrodes is fixed to the base of the sample holder. The base of the sample holder is dug and a conductive substance is filled therein. Make a groove in the base of the sample holder that matches the electrodes of the package. Either is provided.

As a solution to the second problem, at least the Au film and the bonding wire exposed on the sticking surface of the semiconductor device are covered with an insulating cover provided with a variable aperture.

[0023]

[Function] When the sample surface is cleaned by sputtering / etching, all the electrodes of the package are at the same potential as the etching cathode electrode through the holder, so that the accumulation of charges on the surface of the semiconductor device and the discharge between internal elements are eliminated. . Therefore, the decrease of the etch rate and the destruction of the element are eliminated, and the defect can be surely corrected even in the package-mounted semiconductor device.

Further, since only the semiconductor device to be corrected is sputtered / etched, scattering of metal atoms from the chip attaching surface and the bonding wire is eliminated. Therefore, a short circuit between pads can be prevented, and the defect can be surely corrected even in the package-mounted semiconductor device.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, which is a perspective view of a sample holder of a semiconductor device mounted in a PGA type package.

The base 9 on which the package 1 is mounted is metal
It is made of (for example, Al or Ni), and four holes 10 having a size and a depth corresponding to the package 1 and the attached electrode 6 are dug in four places on the upper surface of the base 9. Then, a base cover 11 formed of an electrical insulator (for example, ceramics) is provided to cover the upper surface of the base 9,
Screw holes 12 formed on the upper surface of the base and the base cover
And fix with screws 13. The material of the base cover 11 is an insulating material (alumina sprayed or SiO 2) on a thin metal plate.
₂ or SiN sputtered) may be formed. Further, an enlarged view of the opening 14 is shown in FIG. 4. The base cover 11 has a variable aperture 14a which can be slidably moved by a screw 14b, and when the base cover 11 is attached to the base 9, the opening is opened. Only the part 14 is exposed. Further, on the side surface of the base 9, a groove 100 for automatic transportation is provided.
Is provided, and the transfer arm is inserted into the groove 100 and is transferred to each processing chamber.

FIG. 5 shows a sectional view of AA 'when the base cover 11 is fixed by this structure. When the sputtering / etching process is performed with this sample holder, only the exposed portion of the opening 14 is selectively etched by adjusting the variable aperture 14a to the opening 14 having a size equal to or smaller than that of the semiconductor device. can do. Further, since the opening 14 is changed by adjusting the variable aperture 14a, it is possible to cope with the case where the size of the semiconductor device 2 is different. Moreover, since the surface of the base cover 11 is an electrical insulator, the exposed portion can be uniformly etched.

Next, an embodiment of the sample holder of the present invention is shown in FIG.

This drawing shows an enlarged cross-sectional view of the sample mounting portion, and the electrode 6 of the package to be mounted is placed in the second stage of the hole 10 dug in two stages on the upper surface of the base 9 of the sample holder. Metal mesh with thickness and pitch that match
15 is fixed. The metal mesh 15 is a fixing cover 16
Since it is possible to attach and detach by removing the from the base 9,
The electrodes 6 having different thicknesses and pitches can be dealt with by changing the metal mesh 15. The semiconductor device 2 mounted on the package 1 is mounted on the base 9 by passing the electrodes 6 through the metal mesh 15. At this time, the electrode 6 and the metal mesh 15 are electrically connected. Further, a base cover 11 having an opening 14 of substantially the same size as or smaller than that of the semiconductor device 2 is attached to the upper surface of the base 9 at the same position as the semiconductor device 2, and the bonding formed on the semiconductor device 2 is performed. The wire 4 and the pad 5 are covered with the base cover 11.

When the sputtering / etching process is performed with this structure, only the opening 14 of the base cover 9 is etched. Therefore, other than that, the Au film 3 and the bonding wire 4 on the bonding surface of the semiconductor device 2 are etched. Scattering of metal atoms does not occur. As a result, no short circuit occurs between the pads due to the attachment of metal atoms to the side wall of the package 1 or the shadow of the wire. Also, the electrode 6
And the metal mesh 15 are in electrical contact with each other, the semiconductor device 2 has almost the same potential as the etching cathode electrode through the base 9. Therefore, even if the sputter / etching process is performed, no charge is accumulated on the surface of the semiconductor device 2 or discharge between the internal elements does not occur, so that element destruction does not occur.

Next, FIG. 7 shows another embodiment of the sample holder of the present invention.

Although the basic structure is the same as that of FIG. 6, the difference is that a female connector 16 matching the thickness and pitch of the electrodes 6 is provided instead of the metal mesh 15. The female connector 16 is different from the contact with the electrode 6 in only a part like the metal mesh 15, and is in contact with the electrode 6 so as to cover the entire electrode 6,
It is possible to establish conduction more reliably.

Further, in the case of the metal mesh 15, the contact portion with the electrode 6 is deteriorated by bending or the like depending on the frequency of use, whereas in the case of the female connector 16, such deterioration is not generated. Further, the female connector 16 can also be attached and detached by removing the screw 18. Therefore, like the metal mesh 15, it is possible to deal with various electrodes 6 by changing the thickness and pitch.

Next, FIG. 8 shows still another embodiment.
This has the same basic configuration as in FIGS. 6 and 7,
Instead of providing a metallic fixing member in the second stage of the hole 10 dug in the base 9, the metallic ball 19 is directly filled. The material of the metal sphere is, for example, Al, Ni or SU.
It is a conductive metal such as S. Hole 10 filled with this metal ball 19
The semiconductor device 2 and the base 9 are made to have the same potential by mounting the electrode 6 therein. By using this configuration, it is not necessary to manufacture a fixing member corresponding to the thickness and pitch of the electrodes 6. Further, since the thickness and pitch of the electrodes 6 are not affected at all, it is easy to set the semiconductor device 2 to the same potential as the base 9 even for various configurations of the electrodes 6. However, if the strength of the electrode 6 is low, the metal ball 19
When used, the electrode 6 may be deteriorated such as scratches and bends.

An embodiment for improving this problem is shown in FIG. This is a metal wool formed in the hole 10 of the base 9 filled with the metal balls 19 in the form of fine lines instead of the metal balls 19.
It is filled with 20. By using this metal wool 20, the semiconductor device 2 and the base 9 are set to the same potential without deterioration even in the electrode 6 having low strength. Further, like the metal mesh 15, various electrode 6 configurations can be dealt with.

Further, another embodiment of the sample holder according to the present technology is shown in FIG. The basic structure is the same as that of the above-described embodiments, but the second stage of the hole 10 dug in the base 9 is filled with a liquid metal 21 such as Ga or Hg. With this configuration, when the package 1 is mounted on the base 9, the electrode 6 contacts the liquid metal 21, so that the semiconductor device 2 and the base 9 have the same potential. Further, since it is a liquid, the electrode 6 does not deteriorate due to the contact, and it is possible to cope with various configurations of the electrode 6.

Further, another embodiment is shown in FIG. 11, but the basic configuration is the same as the previous embodiments.

Liquid metal 21 is different from the above-mentioned embodiments.
Instead of, for example, the conductive paste 22 is filled in the second stage of the hole 10 dug in the base 9.

With this configuration, the package 1 is used as the base 9
When it is mounted on the semiconductor device 2, the electrode 6 is fixed by the clay-like substance 22 so that the semiconductor device 2 and the base 9 have the same potential. Further, since it is clay-like, the electrode 6 is more securely fixed without being damaged.

Although the above-mentioned embodiments have been described with respect to the PGA type package sample holders, examples will be described with respect to other types of package sample holders.

FIG. 12 shows an embodiment of the sample holder for a DIP type package.

The basic structure is the same as that of the QFP type package, but the groove 30 corresponding to the thickness and pitch of the electrodes 28 is formed in the base 29. With this configuration, the semiconductor device 24 and the base 29 have the same potential due to the contact between the electrode 28 and the groove 30, so that the semiconductor device 24 and the base 29 have the same potential. No discharge occurs between the internal elements, and no element destruction occurs.

Although the method of forming one groove in one electrode 28 is described in this embodiment, the same effect as in this embodiment can be obtained in the method of forming the groove 30 for one row of electrodes. Is obtained. Further, when this method is used, the semiconductor device is not affected by the pitch of the electrodes 28 and the number of electrodes in one row.
Since 24 and the base 29 can be set to the same potential, various electrode configurations can be accommodated.

Next, an embodiment of the sample holder for the QFP type package is shown in FIG.

FIG. 13 (a) shows a perspective view of a QFP type package mounted on the base 35. The same pitch as that of the connector 36 is provided on the connector 36 for transmitting / receiving signals to / from the outside on the side surface of the package 34. The hook 37 is used for fixing. Like the base 35, the hook 37 is made of a thin elastic conductive material such as Al or SUS. The details of the above configuration are shown in FIG. 13 (b).

A hole 45 having a size larger than that of the package 34 is dug in the upper surface of the base 35 on which the package 34 is mounted, and a hole for fixing the hook 37 is dug in the outer side thereof. The hooks 37 are fixed to the holes 45 in four directions by screws 42 so as to surround the package 34, and when the package 34 is mounted, the hooks 34 are fixed by sandwiching the package 34 from four directions. Further, a base cover 43 having the same structure as the above-described embodiments is attached to the upper surface of the base 35.

When the package 34 is mounted on the base 35 with this structure, the semiconductor device 38 and the base 35 have the same potential due to the contact between the signal transmitting / receiving connector 36 and the hook 37.
Even if the sputter / etching process is performed, electric charge is not accumulated on the surface of the semiconductor device 38 and discharge between internal elements does not occur, so that element destruction does not occur. Further, since the package 34 is sandwiched by the elastic hooks 37 from all sides, the package 34 can be more securely fixed.

[0049]

According to the present invention, it is possible to correct a defective portion even in a package-mounted semiconductor device.

During the sputtering / etching process, all the electrodes of the package have the same potential as the etching cathode electrode through the sample holder due to the metal contact with the sample holder.
No electric discharge occurs between internal elements of the semiconductor device during the sputtering / etching process. As a result, the wiring can be corrected without causing element breakdown.

Further, by covering the bonding wire and the pad portion with the insulating cover provided with the variable aperture, scattering of metal atoms from the chip attachment surface and the bonding wire does not occur during the sputter etching process. As a result, the wiring can be corrected without causing a short circuit between the pads.

[Brief description of drawings]

FIG. 1 is a sectional view of a package.

FIG. 2 is an explanatory view when a package is sputter-etched.

FIG. 3 is a perspective view of a sample holder which is an embodiment of the present invention.

FIG. 4 is an explanatory view of an opening of a base cover shown in FIG.

5 is a cross-sectional view of the sample holder taken along the line AA ′ in FIG.

FIG. 6 is a cross-sectional view of a sample mounting portion of a sample holder that is an embodiment of the present invention.

FIG. 7 is a sectional view of a sample mounting portion of a sample holder that is a second embodiment of the present invention.

FIG. 8 is a sectional view of a sample mounting portion of a sample holder that is a third embodiment of the present invention.

FIG. 9 is a sectional view of a sample mounting portion of a sample holder that is a fourth embodiment of the present invention.

FIG. 10 is a sectional view of a sample mounting portion of a sample holder that is a fifth embodiment of the present invention.

FIG. 11 is a sectional view of a sample mounting portion of a sample holder which is a sixth embodiment of the present invention.

FIG. 12 is a sectional view of a sample mounting portion of a sample holder that is a seventh embodiment of the present invention.

FIG. 13 is a sectional view of a sample mounting portion of a sample holder according to an eighth embodiment of the present invention.

[Explanation of symbols]

 1 ... Package, 2 ... Semiconductor device, 3 ... Au film, 4 ... Bonding wire, 5 ... Pad, 6 ... Electrode, 9 ... Base, 11 ... Base cover, 14 ... Opening part, 15 ... Metal mesh.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 23/32 B

Claims (9)

[Claims] 1. A sample holder used for etching the surface of a semiconductor device in an unsealed package by sputtering, wherein all electrodes of the package are set to substantially the same potential as the etching cathode electrode. holder. 2. The semiconductor device according to claim 1, which has a base cover having an opening which is substantially equal to or smaller than that of the mounted semiconductor device and whose surface exposed to plasma is made of an insulating material. A sample holder that is fixed to expose the. 3. The sample holder according to claim 2, wherein the base cover is formed by spraying an insulator on a metal plate. 4. The sample holder according to claim 2, which uses the base cover whose opening can be adjusted by a variable aperture. 5. The sample holder according to claim 1, comprising a metal mesh into which all the electrodes of the package are inserted so that all the electrodes of the package and the sample holder have substantially the same potential. 6. The sample holder according to claim 1, comprising a female connector into which all the electrodes of the package are inserted so that all the electrodes of the package and the sample holder have substantially the same potential. 7. The sample holder according to claim 1, comprising a metal ball into which all the electrodes of the package are inserted so that all the electrodes of the package and the sample holder have substantially the same potential. 8. The sample holder according to claim 1, comprising metal wool for inserting all the electrodes of the package so that all the electrodes of the package and the sample holder have substantially the same potential. 9. The conductive paste or conductive fluid according to claim 1, wherein all electrodes of the package are inserted so that all electrodes of the package and the sample holder have substantially the same potential. Sample holder.