JP2004093450A - Probe method, probe device, and electrode reduction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a probe method and a probe device as improvement of a conventional inspecting method in which a stylus pressure is given to break an oxide film of an electrode pad involving such a problem that the stylus pressure from a contact shoe may change the electric characteristics such as the transistor characteristics and a stylus pressure as large as breaking the oxide film of the electrode pad can not be given in the case a soft material such as Low-k material having a low diffraction factor is used in the sub-layer of the electrode pad. <P>SOLUTION: The probe method consists of two processes, one in which the electrode pad of a wafer W is subjected to a reduction process using a foaming gas and the second in which the electron pad and a probe pin 14A are put in contact in a dry atmosphere. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a probe method, a probe device, and an electrode reduction device, and more particularly, to a probe method, a probe device, and an electrode reduction device that can enhance electrical contact between a test object and an inspection electrode.
[0002]
[Prior art]
The semiconductor processing process includes various processes such as a process of inspecting a device to be inspected in a wafer state and a process of inspecting a device to be inspected in a package state. When performing an inspection, a contact is brought into contact with an inspection electrode pad of the device under test, and a signal is applied to the device under test via the contact. However, since an electrically insulating oxide film is formed on the inspection electrode pad, conduction cannot be achieved only by bringing the contact into contact, and an inspection signal cannot be applied. There are things you can't do. Therefore, conventionally, after applying a predetermined needle pressure between the electrode pad for inspection and the contact, the contact is scrubbed on the surface of the electrode pad to break the oxide film, and the conduction between the contact and the electrode pad is secured. ing.
[0003]
[Problems to be solved by the invention]
However, with the ultra-high integration of semiconductor products, the thickness of each film formation layer has been accelerated and the electrode pads for inspection have also become thinner, so the needle that breaks the oxide film of the electrode pads as in the conventional probe method. When pressure is applied, electric characteristics such as transistor characteristics may change due to the stylus pressure from the contactor, and a soft material such as a low-k material having a low dielectric constant is used for the lower layer of the electrode pad. In such a case, there is a problem that it is impossible to apply a sufficient needle pressure to break the oxide film of the electrode pad.
[0004]
The present invention has been made in order to solve the above-mentioned problem, and even when a film forming layer such as an inspection electrode is thinned, the probe pin is electrically connected to the inspection electrode without damaging the film forming layer with a needle pressure as low as possible. It is an object of the present invention to provide a probe method, a probe device, and an electrode reduction device that can make reliable contact with each other and ensure reliable electrical connection between them.
[0005]
[Means for Solving the Problems]
The probe method according to claim 1 of the present invention, in the probe method for inspecting the electrical characteristics of the device under test, a step of reducing the test electrode of the device under test using a gas containing hydrogen gas, Contacting the probe electrode with the probe electrode in a dry atmosphere.
[0006]
Further, the probe method according to claim 2 of the present invention is characterized in that, in the invention according to claim 1, in the reduction treatment step, the gas containing hydrogen gas is activated by a platinum group metal or an alloy thereof. It is assumed that.
[0007]
A probe method according to a third aspect of the present invention is the probe method according to the second aspect, wherein a catalyst containing palladium as the platinum group metal is used.
[0008]
A probe method according to a fourth aspect of the present invention is the probe method according to any one of the first to third aspects, wherein the test object is heated in the reduction step. Is what you do.
[0009]
A probe method according to a fifth aspect of the present invention is the probe method according to the first aspect, wherein in the reduction step, the gas containing the hydrogen gas is converted into a plasma and supplied. .
[0010]
A probe method according to a sixth aspect of the present invention is the probe method according to any one of the first to fifth aspects, wherein a forming gas is used as the gas containing the hydrogen gas. It is.
[0011]
A probe method according to a seventh aspect of the present invention is the probe method according to any one of the first to sixth aspects, wherein the inspection electrode is made of copper or a copper alloy. Things.
[0012]
The probe device according to claim 8 of the present invention is a probe device for inspecting an electrical characteristic of an object to be inspected, a means for reducing the inspection electrode of the object to be inspected using a gas containing hydrogen gas. And means for bringing the inspection electrode and the probe pin into contact with each other.
[0013]
A probe device according to a ninth aspect of the present invention is the probe device according to the eighth aspect, further comprising means for forming a dry atmosphere.
[0014]
According to a tenth aspect of the present invention, in the probe apparatus according to the eighth or ninth aspect, the reduction processing means is provided on a prober chamber side for inspecting the inspection object. It is a feature.
[0015]
Also, in the probe device according to claim 11 of the present invention, in the invention according to claim 8 or 9, the reduction processing means is provided on a loader chamber side for loading and unloading the test object. It is characterized by the following.
[0016]
In a probe apparatus according to a twelfth aspect of the present invention, in the invention according to the eleventh aspect, the reduction processing means includes a processing container and a holding unit that is disposed in the processing container and holds the inspection object. And a heating unit for heating the holder, and a unit for supplying a gas containing the hydrogen gas to the object heated via the heating unit. .
[0017]
According to a thirteenth aspect of the present invention, in the probe device according to any one of the eighth to eleventh aspects, the reduction treatment means is a gas supply means for supplying a gas containing hydrogen gas. And a gas flow path for activating the hydrogen gas supplied from the gas supply means under heating, and a heating means for heating the gas flow path.
[0018]
A probe device according to a fourteenth aspect of the present invention is the probe device according to the thirteenth aspect, wherein the gas flow path is formed of a platinum group metal or an alloy thereof. Is what you do.
[0019]
A probe device according to a fifteenth aspect of the present invention is the probe device according to the fourteenth aspect, wherein the platinum group metal is palladium.
[0020]
The probe device according to claim 16 of the present invention is the probe device according to any one of claims 8, 9, and 11, wherein the reduction processing means includes: a processing container; Having a holder disposed in the chamber and holding the object to be inspected, means for supplying a gas containing the hydrogen gas into the processing container, and means for generating plasma from the gas in the processing container It is characterized by the following.
[0021]
An electrode reduction device according to a seventeenth aspect of the present invention is an electrode reduction device provided in a probe device for inspecting electrical characteristics of a device under test, and performing a reduction process on an inspection electrode of the device under test. Gas supply means for supplying a gas containing hydrogen gas, a gas flow path for activating the hydrogen gas supplied from the gas supply means under heating, and a heating means for heating the gas flow path It is characterized by the following.
[0022]
An electrode reduction device according to an eighteenth aspect of the present invention is the electrode reduction device according to the seventeenth aspect, wherein the gas flow path is formed of a platinum group metal or an alloy thereof. .
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on the embodiments shown in FIGS.
The probe method of the present invention performs a reduction process on an oxide film formed on an electrode pad for wafer inspection using a gas containing hydrogen gas (for example, a forming gas that is a mixed gas of hydrogen gas and nitrogen gas). After removal, the probe pins and the electrode pads are brought into contact with each other to perform an electrical characteristic test on the wafer. By reducing the oxide film, the stylus pressure between the probe pin and the electrode pad can be remarkably reduced as compared with the present situation, so that the electrode pad is not damaged by the low stylus pressure and the life of the probe pin can be extended.
[0024]
Therefore, the probe device of the present embodiment will be described first. As shown in FIG. 1, for example, a probe apparatus 10 of the present embodiment includes a loader chamber (not shown) for transporting a workpiece (for example, a wafer) W and a prober chamber 11 for inspecting an electrical characteristic of the wafer W. And a control device (not shown) for controlling various devices described later, which are arranged in both of them.
[0025]
The loader chamber includes, for example, a mounting portion on which a cassette containing 25 wafers W is mounted, a wafer transfer mechanism for transferring wafers W one by one from the cassette in the mounting portion, and a wafer transfer mechanism. And a sub chuck for aligning the wafer in a predetermined direction while transferring the wafer W.
[0026]
Further, the prober chamber 11 moves through three axes (X-axis, Y-axis, and Z-axis) through a three-axis (X-axis, Y-axis, and Z-axis) moving mechanism 12, and has a temperature-adjustable main chuck 13 that rotates forward and reverse in the θ direction. A probe card 14 disposed above the chuck 13 and electrically connected to an electrode pad formed of a conductive metal such as copper, a copper alloy, or aluminum on the wafer W, and a probe pin 14A of the probe card 14. An alignment mechanism (not shown) for aligning the wafer W is provided, and reduction processing means 15 for reducing the electrode pads of the wafer W is provided. The reduction processing means 15 reduces the electrode pads of the wafer W on the main chuck 13 by reduction processing. After that, the probe pins 14A and the electrode pads of the wafer W are brought into electrical contact with each other to perform an electrical characteristic test on the wafer W.
[0027]
The probe card 14 is fixed to a head plate 16 in the prober chamber 11, and a test head T is arranged on the head plate 16 so as to be electrically connectable to the probe card 14. As shown in FIG. 1, the moving mechanism 12 includes a Y table 12A that moves to the bottom surface in the prober chamber 11 in the Y direction (in the drawing, a direction perpendicular to the paper surface), and an X table that moves on the Y table 12A in the X direction. 12B, and a Z-axis mechanism 12C that moves up and down in the Z direction and is arranged so that the center of the X table 12B is aligned with the axis, and moves the main chuck 13 in the X, Y, and Z directions. The main chuck 13 has a built-in temperature control mechanism for controlling the temperature in a range of, for example, -55 ° C to 400 ° C, and rotates in a normal / reverse direction around a central axis through a θ drive mechanism (not shown) within a predetermined range.
[0028]
For example, the reduction processing means 15 heats and flows the forming gas into the prober chamber 11, and forms an electrode formed of copper, a copper alloy, or the like on the wafer heated by the main chuck 13 under normal pressure or reduced pressure. Reduce the pad. As shown in FIG. 1, for example, the reduction treatment means 15 is provided on a head plate 16 and formed of a heat-insulating container 15A made of a heat-resistant material such as quartz or ceramics, and a heater 15B provided in the heat-insulating container 15A. A gas supply pipe 15C connected to the inlet of the heat insulating container 15A, a gas supply means 15D connected to the gas supply pipe 15C and supplying a forming gas, and a mass flow controlling the flow rate of the forming gas from the gas supply means 15D. It has a controller (not shown), and the heater 15B heats the forming gas in the heat insulating container 15A to reduce the electrode pads of the heated wafer W on the main chuck 13 at a predetermined temperature.
[0029]
The heat-insulating container 15A is subjected to a heat-insulating process to prevent the temperature of the heater 15B from lowering and maintain the inside of the heat-insulating container 15A at a predetermined high temperature. As shown in the figure, the inlet of the heat insulating container 15A penetrates the head plate 16 at a position adjacent to the probe card 14, and is arranged to face the main chuck 13. An exhaust port 11A is formed in the prober chamber 11, and the exhaust port 11A is connected to an exhaust device (not shown) via an exhaust pipe 15E. A flat container 15F having an open upper end and surrounding the main chuck 13 is fixed to the elevating mechanism of the moving mechanism 12. This container 15F is formed to have a considerably larger diameter than the main chuck 13, and is filled with the forming gas supplied from the heat insulating container 15A to form a reducing atmosphere in the container 15F. The mounting location of the heat insulating container 15A is not particularly limited as long as the main chuck 13 is moved.
[0030]
As described above, the forming gas is a mixed gas composed of hydrogen gas and nitrogen gas as a carrier gas, and the content of hydrogen gas falls within the explosion-proof range (for example, 5% by volume or less, specifically, It is adjusted to about 3%). As the carrier, a rare gas such as argon or helium can be used in addition to the nitrogen gas.
[0031]
Further, a shield member 15G is provided on the inner surface of the prober chamber 11, and the inside of the prober chamber 11 can be kept airtight by the shield member 15G, and a predetermined reduced pressure state can be formed. An oxygen concentration meter 17 is provided inside and outside the prober chamber 11, and the oxygen concentration inside and outside the prober chamber 11 is monitored via these oxygen concentration meters 17. The oxygen concentration meter 17 is connected to alarm means such as an alarm via a control device, and issues an alarm when the oxygen concentration reaches a dangerous concentration.
[0032]
Further, the probe device 10 is provided with means for supplying dry air, supplies dry air into the prober chamber 11, and inspects the wafer W in a dry atmosphere. The reason why such a dry atmosphere is formed is to prevent the electrode pads on the wafer W from being oxidized by the moisture in the air in the prober chamber 11 even if the electrode pads on the wafer W are reduced by the reduction processing means 15. When supplying dry air into the probe chamber 11, the gas supply pipe 15C of the reduction processing means 15 can be used.
[0033]
Next, an embodiment of the probe method of the present invention using the probe device 10 will be described. First, the probe pins 14A are aligned with the electrode pads of the wafer W in the prober chamber 11 to prepare for starting the inspection. Next, the reduction processing means 15 is driven to exhaust the air in the prober chamber 11 from the exhaust pipe 15E and to supply the forming gas from the gas supply means 15D into the heat insulating container 15A. In the heat insulating container 15A, the heater 15B heats the forming gas. The heated forming gas flows from the outlet of the heat insulating container 15A toward the wafer W on the main chuck 13 and fills the container 15F to form a reducing atmosphere in the container 15F. When the forming gas comes into contact with the electrode pad on the wafer W heated to a temperature of, for example, 200 ° C. or more through the temperature adjustment mechanism of the main chuck 13, the hydrogen gas in the forming gas reduces the oxide film on the electrode pad. Then, the metal of the electrode pad is exposed. Then, the forming gas after the reduction process flows from the container 15F into the prober chamber 11, and is exhausted from the prober chamber 11 to the outside of the prober chamber 11 via the exhaust pipe 15E. During this operation, if the air in the prober chamber 11 is not sufficiently exhausted and the oxygen concentration is higher than a predetermined set value, an alarm is issued and the fact is notified.
[0034]
After reducing the electrode pads by the reduction processing means 15, dry air (for example, having a dew point of -70 ° C.) is supplied into the container 15F to form a dry atmosphere in the container 15F so as to prevent outside air from being mixed. In this state, the moving mechanism 12 and the elevating mechanism are driven, and the probe pins 14A of the probe card 14 and the electrode pads of the wafer W come into contact. At this time, since the oxide film of the electrode pad has been removed, the probe pin 14A and the electrode pad can be brought into electrical continuity only by making contact with a significantly lower stylus pressure than in the past, Inspection of the wafer W can be performed reliably.
[0035]
As described above, according to the present embodiment, a step of reducing the electrode pad under normal pressure or reduced pressure using a forming gas, and a step of electrically contacting the electrode pad and the probe pin 14A under a dry atmosphere. , Electrical contact can be established between the probe pin 14A and the electrode pad only by bringing the probe pin 14A into contact with the electrode pad with an extremely low stylus pressure (for example, 0.2 mN or less). Even if the film formation layer becomes thin, a stable and highly reliable inspection can be performed without damaging the film formation layer by the stylus pressure from the probe pin 14A. In the present embodiment, since the hydrogen gas in the forming gas is activated by the heater 15B, the oxide film on the electrode pad P can be etched and removed by the activated hydrogen in a short time. In addition, since the forming gas and the wafer W are heated, the reduction reaction is promoted by the high temperature, and the electrode pads can be reliably reduced.
[0036]
In the above embodiment, the reduction processing means 15 having the heater 15B is used, but instead of the reduction processing means 15, the heater 15B is omitted and only the gas supply means is provided, and the forming gas is supplied from the gas supply means to the prober chamber 11. And the wafer W heated to a predetermined temperature (for example, 200 ° C. or higher) on the main chuck 13 may be reduced by the forming gas.
[0037]
FIG. 2 is a cross-sectional view showing reduction processing means used in a probe device according to another embodiment of the present invention. The probe device of the present embodiment is configured according to the above embodiment except that the reduction processing means is different. As shown in the figure, the reduction treatment means 25 used in the present embodiment is a palladium pipe (for example, having a diameter of 3 mm) as a gas flow path formed in a pipe shape from a platinum group metal (for example, palladium) or an alloy thereof. 100 mm) 25A, a pipe-shaped heater 25B surrounding the palladium tube 25A, a heat insulating tube 25C for housing the heater 25B, and a double-walled storage tube 25D for housing the heat insulating tube 25C, It is attached to the head plate similarly to the reduction processing means 15 of the above embodiment.
[0038]
Gas supply means (not shown) is connected to the upper end of the palladium pipe 25A via a gas supply pipe 25E, and a gas containing hydrogen gas (for example, forming gas) is supplied from the gas supply means into the palladium pipe A by a mass flow controller. Supply while controlling the flow rate. Each of the heat insulating tube 25C and the storage tube 25D has a bottom surface with an outlet formed at the center. The storage pipe 25D also has a double bottom structure, supplies an inert gas such as nitrogen gas between the double walls, and supplies an inert gas from an outlet into the prober chamber to replace air in the prober chamber. . Further, the palladium tube 25A has a function of activating hydrogen gas, and may be formed in a mesh shape or a sponge shape. In place of the palladium tube 25A, a tube made of a corrosion-resistant material may be filled with a granular palladium catalyst, or a palladium coil may be inserted.
[0039]
Next, the operation of the return processing means 25 will be described. When the reduction processing means 25 is driven, first, nitrogen gas is supplied from the storage pipe 25D into the prober chamber to replace the air in the prober chamber with nitrogen gas, and the palladium pipe 25A is heated via the heater 25B to the activation temperature of hydrogen gas (600 ° C.). ℃ or less). Next, when the forming gas is supplied from the gas supply means 25E to the palladium tube 25A, the hydrogen gas in the forming gas is activated while being in contact with the palladium tube 25A, and the forming gas flows out toward the wafer in the prober chamber, and the heated wafer is heated. The oxide film on the upper electrode pad is reduced. This reduction processing means 25 can be preferably used when a metal pad formed of, for example, copper or a copper alloy is subjected to reduction processing. In this embodiment, the same operation and effect as those of the above embodiment can be expected.
[0040]
FIG. 3 is a schematic view showing reduction processing means used in a probe device according to still another embodiment of the present invention. The probe device of the present embodiment is configured according to the above embodiments, except that the reduction processing means is different. The reduction processing means 35 used in the present embodiment is provided in the loader chamber 16 as shown in the figure, and reduces the electrode pads of the wafer W in the loader chamber 16 before the inspection of the wafer W. The reduction processing means 35 includes a processing container 35A, a holder 35B having a temperature control mechanism for heating and cooling the wafer W in the processing container 35A, and a plurality of elevating pins 35C for transferring the wafer W on the holder 35B. A heating vessel 35E provided above the processing vessel 35A and having a heater 35D, a gas supply pipe 35F connected to the heating vessel 35E, and a gas exhaust pipe 35G connected to the processing vessel 35A. After the forming gas introduced through the supply pipe 35F is heated in the heating vessel 35E, it is introduced into the processing vessel 35A to reduce the electrode pads of the wafer W. A wafer transfer mechanism 16A is provided in the loader chamber 16, and transfers the wafer W between the cassette C and the processing container 35A via the wafer transfer mechanism 16A. It is preferable that the inside of the loader chamber 16 is supplied with dry air in the same manner as the prober chamber so as to adjust to a dry atmosphere. Reference numeral 35H denotes an opening / closing door for opening and closing the processing container 35A.
[0041]
Next, the operation of the return processing means 35 will be described. First, the wafer W is taken out of the cassette C via the wafer transfer mechanism 16A in the loader chamber 16 and transferred into the processing container 35A with the opening / closing door 35H opened. Is placed on the wafer W. Subsequently, the elevating pins 35C descend to place the wafer W on the holder 35B. Then, while the wafer W is heated to a predetermined temperature by the temperature adjusting mechanism of the holder 35B, the forming gas is supplied from the gas supply pipe 35F. The forming gas is heated by the heater 35D in the heating container 35E, reaches approximately the same temperature as the wafer W, flows into the processing container 35A, and reduces the electrode pads of the wafer W at a high temperature. After the reduction, the wafer W is taken out of the processing vessel 35A via the wafer transfer mechanism 16A, and then transferred into the prober chamber, where the inspection is performed in the prober chamber. In this embodiment, the same operation and effect as those of the above embodiments can be expected.
[0042]
FIG. 4 is a cross-sectional view showing reduction processing means used in a probe device according to still another embodiment of the present invention. The probe device of the present embodiment is configured according to the above embodiments, except that the reduction processing means is different. As shown in the figure, the reduction processing means 45 used in the present embodiment includes a processing chamber 45A which is connected to a loader chamber (not shown) which can be adjusted to a dry atmosphere and which can be shut off, and a processing chamber 45A. A mounting table 45B also serving as a lower electrode disposed in the mounting table 45A, an upper electrode 45C disposed in parallel above the mounting table 45B and having a large number of gas supply holes, and a gas supply for supplying a forming gas into the processing chamber 45A. A source 45D and an exhaust device (not shown) for exhausting gas in the processing chamber 45A are provided, and are connected to the loader chamber via a gate valve G so as to be able to communicate and shut off.
[0043]
Further, as shown in FIG. 2, for example, the mounting table 45B includes a lower electrode 45F connected to a 13.56 MHz high-frequency power supply 45E, a heating unit 45G having a heater, and a coolant disposed below the heating unit 45G. A cooling unit 45H having a flow path, and an elevating pin (not shown) for elevating and lowering the wafer W on the mounting surface are provided, and high-frequency power is applied from the high-frequency power supply 45E to the lower electrode 45F under a predetermined reduced pressure. A plasma of a forming gas is generated between the electrode and the electrode 45C. The heating unit 45G and the cooling unit 45H appropriately adjust the temperature of the wafer W on the mounting table 45B. The gas supply source 45D includes, for example, a hydrogen gas supply source 45I for supplying hydrogen gas, a nitrogen gas supply source 45J for supplying nitrogen gas, and a gas flow rate control mechanism for adjusting the flow rate of each gas, as shown in FIG. 45K, a hydrogen gas is adjusted to a predetermined concentration via a gas flow control mechanism 45K, supplied as a forming gas into the processing chamber 45A, and the processed gas is exhausted from a gas exhaust pipe 45L.
[0044]
Next, the operation of the return processing means 45 will be described. First, when the wafer is taken out of the cassette in the loader chamber, the wafer is placed on the mounting table 45B in the processing chamber 45A from the loader chamber via the wafer transfer mechanism before the wafer inspection, and the gate valve G is closed. After shutting the inside of the processing chamber 45A from the outside air, exhausting the air in the processing chamber 45A through an exhaust device and purging the air in the processing chamber with nitrogen gas, hydrogen gas and nitrogen are supplied from the gas supply source 45D into the processing chamber 45A. After a forming gas composed of a gas is supplied at a predetermined flow rate and the air is replaced with the forming gas, the inside of the processing chamber 45A is maintained at a pressure capable of performing plasma. Next, high-frequency power is applied to the lower electrode 45F to generate plasma of a forming gas between the lower electrode 45F and the upper electrode 45C, and the oxide film on the copper electrode pad of the wafer W is etched by the plasma. Thereafter, the cooling unit 45F is operated to rapidly cool the wafer W to lower the temperature of the wafer W to normal temperature, and then the supply and exhaust of the forming gas are stopped. Then, the gate valve G is opened, and the wafer transfer mechanism enters the processing chamber 45A, carries the wafer W from the processing chamber 45A into the loader chamber, and closes the gate valve G. Thereafter, the wafer W is transferred to the prober chamber via the loader chamber adjusted to a dry atmosphere. Thereafter, the inspection of the wafer W is performed in the prober chamber as in the above embodiments. In this embodiment, the same operation and effect as those of the above embodiments can be expected.
[0045]
【Example】
In the present example, the effects of copper oxidation, reduction phenomenon, and humidity on oxidation were specifically observed by experiments, and the effect of reduction was confirmed by specifically executing the probe method of the present invention.
[0046]
Example 1
In this example, the reducing performance of the forming gas was observed. That is, an oxide film of a reference copper wafer (copper thin film = 1 μm, TiN base = 15 nm) (hereinafter simply referred to as “reference wafer”) is subjected to a reduction treatment in a forming gas atmosphere, and an oxygen concentration distribution in the copper thin film is obtained. Was observed. Specifically, the forming wafer (hydrogen gas concentration = 3% by volume) is supplied while the reference wafer is placed on the main chuck and the reference wafer is heated by the main chuck set at 350 ° C. After exposing the reference wafer under an atmosphere, the oxygen concentration distribution in the copper thin film was observed by an X-ray photoelectron spectrometer (XPS). Similarly, only the nitrogen gas was supplied while the reference wafer was heated, and the reference wafer was exposed to a nitrogen gas atmosphere. Then, the oxygen concentration distribution in the copper thin film was observed by XPS. FIG. 5 shows these results. According to the results shown in FIG. 5, when the forming gas is supplied, the oxygen concentration becomes 0 at% before the depth reaches 10 nm from the surface of the copper thin film, that is, the oxide film becomes much thinner than the reference wafer. It was found that the oxide film was surely reduced by the forming gas. On the other hand, it was found that the oxygen concentration was higher in the non-oxidizing atmosphere supplied with the nitrogen gas than in the reference wafer.
[0047]
Example 2
In the present example, the effect of the temperature of the main chuck when reducing the oxide film of the reference wafer using the forming gas was observed. That is, as shown in FIG. 6, the temperature of the main chuck was changed to 250 ° C., 300 ° C., 325 ° C., and 350 ° C., and the oxygen concentration distribution in the copper thin film at each temperature was observed by XPS. Indicated. According to the results shown in FIG. 6, it was found that the higher the temperature of the main chuck, the more the reduction was promoted.
[0048]
Example 3
In this example, the effect of humidity on oxidation was observed. That is, the wafer was left in dry air (dew point = -70 ° C.), air (temperature = 25 ° C., humidity = 50%) and nitrogen gas for the time shown in FIG. The progress of oxidation of the copper wafer (copper thin film = 1 μm, TiN underlayer = 15 nm) was observed, and the results are shown in FIG. 7A. In addition, the oxidation rate in dry air and the oxidation rate in air were obtained, and the results are shown in FIG. 7A shows the distribution of the oxygen concentration in the copper thin film immediately after the production of the copper wafer. According to the results shown in FIGS. 7A and 7B, it was found that the longer the standing time in the humid atmosphere, the more the oxidation of the copper thin film progressed, and the thicker the oxide film to be reduced. On the other hand, it was found that oxidation did not proceed so much in dry air as compared with a copper wafer immediately after fabrication even if the standing time was long. Therefore, even after the reduction, it was found that the inspection can be performed with a lower stylus pressure by performing the inspection in the dry air without performing the inspection in the humid atmosphere.
[0049]
Example 4
In this example, the relationship between the stylus pressure of the probe pins and the contact resistance of the oxide film on the copper wafer under a dry atmosphere was observed. That is, after reducing a copper wafer under the following conditions using hydrogen gas and storing it in a nitrogen gas atmosphere for 20 minutes, the reduced copper wafer is placed on a main chuck and dried air (dew point = −70 ° C.). ) Below, the main chuck is overdriven in three stages of 0 μm, 10 μm, and 30 μm, and the contact resistance between the copper wafer and the probe pins at each point is measured, and the relationship between the overdrive amount (needle pressure) and the contact resistance is illustrated. 8 (a) to (c). For comparison, the stylus pressure and contact resistance of the probe pins were measured in the same manner under dry air (dew point = -70 ° C.) using a copper wafer not subjected to reduction treatment, and the results were shown in FIGS. (C). Here, when the overdrive (OD) amount is OD = 0 μm, OD = 10 μm, and OD = 30 μm, the stylus pressure was 0, 15 mN, and 50 mN, respectively. In addition, when all the 35 probe pins of the probe card were in contact with the center of the copper wafer and the resistance value was 5Ω or less, OD = 0 μm. The variation in the Z direction was 10 μm or less.
[Reduction treatment conditions]
Pressure in the processing chamber: 133.332 Pa
Main chuck temperature: 400 ° C
Main chuck heating time: 5 minutes
Reduction treatment time with hydrogen gas: 15 minutes
Flow rate of hydrogen gas: 500 sccm
Wafer cooling time: 15 minutes
[0050]
According to the results shown in FIGS. 8A to 8C, when the overdrive amount is 0 μm, that is, when only the copper wafer and the probe pins are in contact, the contact resistance value as shown in FIG. May exceed 1.0Ω, but it was found that the contact resistance decreased as the number of measurements increased. It was found that when the overdrive amount became 10 μm, the contact resistance value was remarkably lowered to 0.2Ω or less from the initial stage of the measurement, and the conductivity between the copper thin film and the probe pin was extremely improved. Further, it was found that even when the overdrive amount was increased to reach 30 μm, the contact resistance value was hardly changed from the case of 10 μm. Therefore, it was found that the inspection of the wafer could be reliably performed with an overdrive amount of 10 μm, that is, a needle pressure as low as 15 mN. On the other hand, in the case of a copper wafer not subjected to the reduction treatment, as is clear from the results shown in FIGS. 9A to 9C, the overdrive amount is 30 μm even in a dry air atmosphere. That is, it was found that the wafer could be inspected unless the stylus pressure was as high as 50 mN.
[0051]
Example 5
In this example, the effect of humidity on the contact resistance between the copper wafer after reduction and the probe pins was observed. That is, dry air (dew point = -70 ° C.) is supplied at a flow rate of 300 L / min, and the copper wafer is overdriven by 10 μm in a dry atmosphere to bring the copper wafer into contact with the probe pins to reduce the contact resistance of the entire copper wafer. The measurement was performed, and the results are shown in FIG. The reduced copper wafer was overdriven by 10 μm in air (temperature = 25 ° C., humidity = 50.1%) to bring the copper wafer into contact with the probe pins, and the contact resistance of the entire copper wafer was measured. The results are shown in FIG.
[0052]
According to the results shown in FIGS. 10A and 10B, the resistance was stable at a low resistance value of 1 Ω or less over the entire surface of the copper wafer in a dry atmosphere, but the contact resistance value was lower in the air in the middle of the measurement time. Was found to be significantly higher. In this embodiment, a probe card of a 14-pin type which generates a load of 0.2 mN with a 10 μm overdrive was used as the probe card. From the above, it was found that the test can be performed reliably at a low needle pressure of about 0.2 mN even in a long time of 4 hours or more in dry air after the reduction treatment. In the inspection in air, the copper wafer on the main chuck is lower at the center than the periphery, so even with the same overdrive amount, the stylus pressure at the center is lower than the periphery and the contact resistance value is higher. I have.
[0053]
The present invention is not limited to the above embodiment. For example, the wafer reduction processing means may employ various modes other than the configurations shown in the above embodiments. Further, the gas containing hydrogen gas is not limited to the forming gas, and a carrier gas can be appropriately selected and used as needed. Further, the wafer reduction processing can be performed on the wafers in the cassette at a time. Further, in the above embodiment, the wafer W is used as the inspection object, but the present invention can be applied to package products other than the wafer.
[0054]
【The invention's effect】
According to the invention as set forth in claims 1 to 18 of the present invention, even if a film forming layer such as a test electrode is thinned, the probe pin is not damaged by the probe pin with the lowest possible stylus pressure. To provide a probe method, a probe device, and an electrode reduction device that can be electrically contacted with each other, reliably conduct between them, and reliably perform a highly reliable inspection.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of a probe device of the present invention.
FIG. 2 is a cross-sectional view showing a reduction treatment device applied to another embodiment of the probe device of the present invention.
FIG. 3 is a cross-sectional view showing a reduction treatment apparatus applied to still another embodiment of the probe device of the present invention.
FIG. 4 is a cross-sectional view showing a reduction processing apparatus applied to still another embodiment of the probe device of the present invention.
FIG. 5 is a graph showing the distribution of oxygen concentration in a copper thin film when a copper wafer is subjected to a reduction treatment using one embodiment of the probe method of the present invention, together with a comparative example.
FIG. 6 is a graph showing the distribution of the oxygen concentration in the copper thin film and the temperature of the copper wafer when performing the reduction treatment of the copper wafer using one embodiment of the probe method of the present invention.
7A and 7B are diagrams showing the influence of humidity on oxidation of a copper wafer after reduction. FIG. 7A shows the distribution of the temperature of the copper wafer and the oxygen concentration in the copper thin film when left in dry air or air for a predetermined time. (B) is a graph showing the oxidation rate in dry air and air.
FIGS. 8A to 8C are diagrams showing one embodiment of the probe method of the present invention, and are graphs showing a relationship between an overdrive amount and a contact resistance value.
9 (a) to 9 (c) are graphs corresponding to FIGS. 8 (a) to 9 (c), respectively, showing the relationship between the overdrive amount and the contact resistance value of a copper wafer not subjected to a reduction treatment.
FIG. 10 (a) is a graph showing the change over time in the contact resistance of a copper wafer measured by one embodiment of the probe method of the present invention, and FIG. 10 (b) is a copper measured in the atmosphere of a reduced copper wafer. 5 is a graph showing a change over time in a contact resistance value of a wafer.
[Explanation of symbols]
10 Probe device
11 Prober room
13 Main chuck (contact means)
14 Probe card
15, 25, 35, 45 reduction treatment means
15A heat-resistant container
15B, 25B, 35D heater (heating means)
15D gas supply means
15F container (processing container)
16 Loader room
25A Palladium tube (gas flow path)
35A processing container
35B holder
45C upper electrode (plasma generating means)
45F lower electrode (plasma generating means)
W wafer (inspection object)

Claims (18)

In a probe method for inspecting electrical characteristics of an object to be inspected, a step of reducing the electrode for inspection of the object to be inspected using a gas containing hydrogen gas, and contacting the electrode for inspection with a probe pin in a dry atmosphere. A probe method. 2. The probe method according to claim 1, wherein in the reduction step, the gas containing hydrogen gas is activated by a platinum group metal or an alloy thereof. The probe method according to claim 2, wherein a catalyst containing palladium as the platinum group metal is used. The probe method according to any one of claims 1 to 3, wherein the test object is heated in the reduction processing step. 2. The probe method according to claim 1, wherein, in the reduction process, the gas containing the hydrogen gas is converted into a plasma and supplied. The probe method according to any one of claims 1 to 5, wherein a forming gas is used as the gas containing the hydrogen gas. The probe method according to any one of claims 1 to 6, wherein the inspection electrode is made of copper or a copper alloy. In a probe device for inspecting an electrical characteristic of an object to be inspected, a means for reducing an electrode for inspection of the object to be inspected using a gas containing hydrogen gas, and a means for bringing the electrode for inspection into contact with a probe pin are provided. A probe device, comprising: 9. The probe device according to claim 8, further comprising means for forming a dry atmosphere. 10. The probe device according to claim 8, wherein the reduction processing means is provided on a prober chamber side for inspecting the inspection object. 10. The probe device according to claim 8, wherein the reduction processing means is provided on a loader chamber side for loading and unloading the object to be inspected. The reduction processing means includes a processing container, a holder disposed in the processing container and holding the object to be inspected, a heating means for heating the holder, and the heating member heated via the heating means. 12. The probe device according to claim 11, further comprising: means for supplying a gas containing the hydrogen gas to the processing body. The reduction treatment means includes a gas supply means for supplying a gas containing hydrogen gas, a gas flow path for activating the hydrogen gas supplied from the gas supply means under heating, and a heating means for heating the gas flow path The probe device according to any one of claims 8 to 11, further comprising: The probe device according to claim 13, wherein the gas flow path is formed of a platinum group metal or an alloy thereof. The probe device according to claim 14, wherein the platinum group metal is palladium. The reduction processing means includes: a processing container; a holder disposed in the processing container and holding the object to be inspected; a unit for supplying a gas containing the hydrogen gas into the processing container; 12. The probe apparatus according to claim 8, further comprising: means for generating plasma from the gas. An electrode reduction device provided in a probe device for inspecting electrical characteristics of an object to be inspected, for reducing an inspection electrode of the object to be inspected, wherein a gas supply means for supplying a gas containing hydrogen gas; An electrode reduction device comprising: a gas flow path for activating a hydrogen gas supplied from a supply means under heating; and a heating means for heating the gas flow path. The electrode reduction device according to claim 17, wherein the gas flow path is formed of a platinum group metal or an alloy thereof.

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