JPS60239036A - Semiconductor wafer prober - Google Patents

Abstract

PURPOSE:To check generation of electrically inferior contact at a semiconductor wafer prober by a method wherein an air washer to blow gas containing no impurity against a wafer is provided in the transportation cource of the semiconductor wafer to be measured, and the surface of the wafer is cleaned prior to functional measurement of ICs provided to the wafer. CONSTITUTION:A full automatic semiconductor wafer prober is constructed of a probing machine part and a wafer transportation part, and wafers are transferred onto a belt conveyer BC by moving upwards and downwards cassettes CA1, CA2 loading with the wafers in multistages according to an elevator mechanism provided to the transportation part. Moreover an X-Y table TB, a Z table not shown in the figure, and an image pickup device ITV are provided to the machine part, and moreover a microscope MS and a CRT to project a monitor picture and placed adjoining thereto are provided on the Z table. After then, the microscope MS is laid down, the prober is positioned to the place thereof, and various characteristics of the wafer are measured, while at this time, clean air is jetted from an air shower AS provided to the machine part, and the surface of the wafer sucked to a chuck CT is cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a semiconductor wafer prober, and relates to, for example, a technique effective for use in a fully automatic semiconductor wafer prober.

[Background technology]

Semiconductor wafer probers, which are responsible for the final checking process of semiconductor wafers, have become so-called tweezers-less, or in other words, due to the increasing diameter of semiconductor wafers, it has become difficult to perform manual work using tweezers or other tools. , automatic loading and unloading of semiconductor wafers was published in ``Electronic Materials J Magazine, November 1978 issue, pages 139~
143. In other words, the semiconductor wafers stored in the storage container (cassette) containing a plurality of semiconductor wafers (for example, 25 wafers) are sequentially loaded one by one.
The sheets are transferred one by one to the load stage (coarse alignment stage) by a round belt conveyor. Then, this semiconductor wafer is transported to a wafer chuck top (measuring table) of a blobbing machine section using a Bernoulli chuck or the like. Next, the semiconductor wafer on which the measurement has been completed is carried out from the wafer chuck top to the unloading stage by blowing air pressure or the like, and placed in a storage container by a round belt conveyor. As described above, the semiconductor wafer is carried into and taken out of the blobbing machine section in a completely non-contact state with respect to the surface of the semiconductor wafer.

By the way, in the manufacturing process of semiconductor wafers, since circuit patterns are formed using precise photographic technology, semiconductor wafers are handled in a clean room. However, the blobbing process is performed in a room equipped with a printer using plain paper, which is part of an RC (integrated circuit) tester using a computer system. For this reason, even if a bin setless system is attempted as described above, since the air contains a relatively large amount of dust, fine dust will adhere to the semiconductor wafer. This dust itself does not adversely affect the circuit function of the semiconductor integrated circuit device completed on the semiconductor wafer.

However, if fine dust (several tens of microns) adheres to the surface of the semiconductor wafer, a thin wire probe needle is pressed against the bonding bath of the semiconductor integrated circuit completed on the semiconductor wafer to send and receive signals. This sometimes causes poor contact.

This is because the diameter of the contact end of the probe needle is approximately 50 mm.
This is because even extremely fine dust can cause electrical contact failures since the thickness is about μ. When such electrical contact failures occur, good semiconductors/integrated circuits become defective, which means that the money spent in the masked wafer process is wasted, and in other words, the yield of semiconductor integrated circuit devices deteriorates. Therefore, the problem arises that the cost becomes high.

[Purpose of the invention]

An object of the present invention is to provide a semiconductor wafer prober that achieves high measurement reliability.

The above and other objects and novel features of this invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, an air shower is provided in the transfer path of the semiconductor wafer, and the surface of the semiconductor wafer is cleaned prior to the measurement.

〔Example〕

FIG. 1 shows an external view of an embodiment of a fully automatic semiconductor wafer prober to which the present invention is applied.

The fully automatic semiconductor wafer prober shown in the figure can be roughly divided into a blowing machine section and a semiconductor wafer transfer section. The semiconductor wafer transfer section includes cassettes CAL and CA that store a plurality of semiconductor wafers in a multi-stage configuration in the vertical direction.
2, and a round belt conveyor BC that transfers the semiconductor wafer between the elevator mechanism and the load stage and unload stage for the blowing machine section. It consists of this.

The load stage is provided with means for rotating the semiconductor wafer transferred thereto and detecting its orientation flat, and performs a preliminary operation of positioning the semiconductor wafer in the θ direction.

On the other hand, although the blobbing machine part is not visible from the outside,
It is composed of an X-Y table X-YTB. This X-
A wafer chuck top (semiconductor wafer mounting table) is attached to the Y table X-YTB, which is driven by a pulse motor for highly precise position control. The wafer chuck top has a suction hole for vacuum suctioning the semiconductor wafer, and a blow-off hole for transporting the semiconductor wafer after measurement to the unloading stage (which may also be used in conjunction with the suction hole described below). ) is provided. Further, the wafer chip top and Z stage are provided, and the semiconductor wafer is pushed up against the probe needles of the fixed probe board attached to the opening at the top of the X-Y table X-YTB. Electrical contact is made between the bonding pad of the probe needle and the contact end of the probe needle.

The microscope MS is used to confirm the alignment (needle alignment) between the contact end of the probe needle and the surface of the semiconductor wafer through the above-mentioned aperture, or to confirm the alignment (needle alignment) between the contact end of the probe needle and the surface of the semiconductor wafer, or as a preliminary inspection in case of failure of automatic alignment as described later. It is used for observing manual needle alignment.

The semiconductor wafer whose orientation flat has been detected on the load stage is transferred to a wafer chuck top that is moved to a load position by a transfer arm as described later. Above this load position, an imaging device I consisting of a television camera etc. is installed in order to realize automatic needle adjustment.
A TV is provided. The digitized circuit pattern signal of the semiconductor wafer formed by the image pickup device ITV is pattern recognized by an image processing device (not shown), and the position of the bonding pad is identified. The display device CRT is used as a main device to display its monitor screen.

The operation panel PNL is used to input various manual control signals such as starting and stopping the above operations.

In addition, the blobbing machine part (X-Y table
T B ;/) (The stored part) The upper iPL is configured so that it can be opened at the top as shown by the arrow in the same figure, although it is not particularly limited.
A printed circuit board (fixed probe board) to which probe needles are fixed is loaded with L open.

For this reason, the microscope MS is equipped with a function that allows it to rotate forward and backward as indicated by the arrow in the figure.
The upper lid PL is opened and the microscope MS is tilted backward. The reason for this configuration is to use the upper lid PL as a cover to block the outside air from dust-proofing the entire semiconductor wafer transfer path as will be described later.

Figure 2 shows the above 1st FI! A schematic diagram of the main internal mechanisms in the fully automatic semiconductor wafer prober shown in FIG. Therefore, the microscope @@MS, the display device CRT, and the image pickup device ITV in FIG. 1 are not shown.

As described above, the blowing machine section moves the wafer chuck top CT, which suctions and fixes the semiconductor wafer placed on its upper surface, in the X and Y directions or rotates it in the θ direction using the X-Y table X-YTB. A probe consisting of a fixed probe board, etc., whose tip is aligned with the bonding pad of a wafer chip (semiconductor integrated circuit) with a probe needle (tip) arranged corresponding to the measurement location. It is. Although not particularly limited, alignment is performed by rotating the semiconductor wafer in the θ direction at the load position LP, that is, aligning the X-axis of the chip arrangement on the semiconductor wafer with the X-Y table -X- Match the X axis of YTB. Furthermore, the position of the bonding pad is detected by the pattern recognition operation. Based on this position detection data, the position of the bonding pad is calculated when the semiconductor integrated circuit (chip) to be measured first on the wafer chuck top CT is moved to the position of the probe needle on the fixed probe board. Automatic needle adjustment is performed. This automatically aligns the tip of the probe needle with the bonding pad of the first wafer chip to be measured. Thereafter, by continuously moving the probe in the X direction or the Y direction at intervals of one chip at a time, the probe is automatically aligned with the bonding pads of other wafer chips. These X-Y tables X-YT
Movement control of B is performed with high precision using a pulse motor. Further, the wafer chuck top CT is moved in two directions (up/down) using air or a pulse motor. That is, the positioning operation by the X-Y table X-YTB is performed with the wafer chuck top CT lowered, and during measurement, the wafer chuck top CT is
With the probe needle pushed up, the probe needle and the bonding pad of the wafer chip are brought into contact with a required contact pressure to establish an electrical connection.

Since such a stage mechanism is well known, a more detailed explanation will be omitted.

The transfer arm TB uses, for example, a Bernoulli chuck that attracts the semiconductor wafer below the surface without contact, and by moving this chuck from side to side in the figure, the semiconductor wafer transferred to the load stage LS is moved to the load position LP. The wafer is carried into the chuck top CT which has been moved to In addition, after the semiconductor wafer has been measured, after the wafer chuck top CT is moved to the unloading position UL, air is blown out from the suction port, etc., and the semiconductor wafer is moved to the unload stage of the transfer section Exported to US.

A semiconductor wafer transfer section (the right section in the figure) is provided for a blobbing machine section (the left section in the figure) equipped with such an automatic semiconductor wafer loading and unloading mechanism. The semiconductor wafer transfer section in this embodiment includes four elevator mechanisms E1 to E4 in which storage containers (cassettes) CAI, CA2, etc. as shown in FIG. 1 are installed to store semiconductor wafers, and a course alignment A round belt conveyor BC is provided that connects the load stage LS and unload stage US, which also operate as stages.

In the figure, this round belt conveyor includes a pair of round bells 1-Bl running vertically in the center of the transfer section, and this round belt 1-Bl.
Four pairs of round bells ) 82 to B5 run perpendicularly on the right side of Bl and connect with the elevator mechanisms E1 to E4, and a round bell running in the center of the above are connected to the elevator mechanisms E1 to E4. 2 which runs at right angles to the left side and connects with the load stage LS and unload stage US.
Pair of round bells 1-B6. B7. Each of the round belt conveyors B1 to B7 is provided with a driving pulley and a free pulley at both ends, and the driving pulley is driven by a motor (not shown) via a similar round belt. A conveyor consisting of a pair of round belts is run, and the semiconductor wafers placed thereon are transported. Guides (not shown) are provided on both sides of these pair of round belts. This prevents the semiconductor wafer from falling off the pair of round belts. Further, a sensor (shown in the figure) is provided at the transfer point (connection point) of the semiconductor wafer between the round belt conveyors. Although not particularly limited, this sensor is configured by an optical sensor and detects the semiconductor wafer transferred to the top thereof. for example,
When the semiconductor wafer to be measured is transferred from top to bottom by the round belt conveyor B1 running in the center, when the sensor detects that the semiconductor wafer has been transferred to the position where it is connected to the load stage LS, The transfer operation of the round belt conveyor B1 running in the center is stopped. When the round belt conveyor B6 connected to the load stage 2 LS is started to operate, it transfers the semiconductor wafer and transfers it to the load stage LS.

The semiconductor wafer transfer operations along other routes are also similar to those described above, and therefore their explanations will be omitted. Further, since the elevator mechanism E1 and the like are well known, for example, from Japanese Patent Application Publication No. 54-48482, a detailed explanation thereof will be omitted.

In this embodiment, although not particularly limited, an air shower As is provided on the left side of the load body LP of the wafer chuck top CT. This air shower As will be explained next with reference to the schematic sectional view of FIG.

The air shower As of this embodiment blows out a lean gas such as dry nitrogen from a plurality of small holes at a relatively high pressure. This blows away dust and the like on the surface of the semiconductor wafer W vacuum-adsorbed by the wafer chuck top CT. Note that after the semiconductor wafer W is transferred to the wafer chuck top CT by the transfer arm TA, the wafer chuck top CT
is once moved to the bottom of the air shower As, and then moved left and right multiple times. Thereby, the entire surface of the semiconductor wafer W is cleaned by the air shower AS. And a hundred,
The wafer chuck top CT is in the load position L above.
The needle is moved to P, where the pattern recognition operation for automatic needle rest adjustment is performed.

In addition, in order to prevent dust in the room from adhering to the surface of the semiconductor wafer during measurement, a dust-proof means such as a dust-proof cover is installed on the semiconductor wafer transfer path as shown by the dotted line in the same figure. It will be done.

The structure of this dustproof means will next be explained with reference to FIG.

FIG. 4 shows a schematic cross-sectional view of one embodiment of the main part of the dustproof means.

The entire interior of the semiconductor wafer prober is covered by an upper cover UC, a lower cover LC, and side covers (not shown), as shown in the figure. (It can also be the cover itself). In addition, although not particularly limited, pipes PP provided with small holes UH for blowing out lean gas such as dry nitrogen are arranged at appropriate intervals in the upper cover UC. Although not particularly limited, the lower cover LC is provided with an exhaust hole LH as the exhaust means. The air pressure of the vibrator PP is set to be slightly higher than the indoor air pressure. That is, the consumption of dry nitrogen is reduced, and the atmospheric pressure inside the semiconductor wafer prober is set to be slightly higher than the atmospheric pressure in the room in which it is installed. As a result, exhaust is always carried out, for example, from the above-mentioned exhaust port LH or an opening provided to allow semiconductor wafers to pass through to the position of the round belt through which semiconductor wafers are transferred from the cassette. This prevents indoor dust and the like from entering the inside of the prober.

5. In addition, a transparent cover is used to cover the opening WD below the microscope MS and the objective lens position of the imaging device ITV in FIG.

Note that if the surface of the semiconductor wafer is irradiated with light during the measurement, the aperture WD will have an adverse effect on the characteristics of the semiconductor element, so for example, a slide-type shutter is provided, which is used as a dust-proof cover. It may be possible.

〔effect〕

(11 Air shower can remove fine dust, debris, etc. attached to the surface of a semiconductor wafer before measurement, so it is useful when performing measurements on semiconductor urchins (functional tests of semiconductor integrated circuits formed on semiconductor wafers). It is possible to prevent poor electrical contact between the probe needle and the bonding pad due to the above-mentioned dust, etc. This prevents a good semiconductor integrated circuit from being incorrectly judged as defective, making it possible to achieve highly reliable measurements. This effect can be obtained.

(2) The effect of (11) above is that the number of good semiconductor integrated circuits obtained from one semiconductor wafer increases, and the yield of semiconductor integrated circuit devices can be increased, thereby reducing the manufacturing cost. is obtained.

(3) When performing automatic needle rest twisting by pattern recognition operation, dust etc. can be removed by the cleaning device mentioned above, so there is no need to worry about malfunctions such as recognizing fine dust as a circuit pattern or wasting time until finding the desired pattern. The effect is that the movement can be prevented.

(4) By providing a dustproof means inside the semiconductor wafer prober, semiconductor wafers can be measured in a clean state. This, in combination with the effect of (1) above, can prevent electrical contact failures caused by indoor dust, etc., resulting in the effect of realizing measurement tests with higher reliability. It will be done.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that this invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, the cleaning device may be provided on a load stage (coarse alignment stage). In this case, it is desirable to provide vacuum suction means or the like on this stage so that the semiconductor wafer is not blown away by the relatively high pressure gas jet. In addition, the air shower and the gas that makes the interior high-pressure do not contain any impurities such as dry nitrogen or dust that would impair the electrical contact of the probe needle, and do not corrode metal surfaces such as aluminum in semiconductor integrated circuits. Any stable gas may be used. Further, a dustproof cover may also be provided on the part where the cassette is attached. in this case,
This cover may be constructed so that it can be opened and closed in order to load or remove the cassette into the elevator.

Note that the needle alignment for the semiconductor wafer may be performed manually by visual observation using a microscope. That is, after the semiconductor wafers that are automatically sent one after another from the transfer section are placed on the wafer chuck top, the first step is to visually measure the positioning of the contact end of the bonding pad of the semiconductor integrated circuit and the probe needle ( needle alignment)
It may also be something that does this. Further, the means for transporting the semiconductor wafers may be any means other than the above-mentioned round belt conveyor, such as using an air bearing.

Furthermore, in order to increase the versatility of the system, it is preferable that the operation control of the above-mentioned blowing machine section and the operation control of semiconductor wafer transfer be performed by program control using a microcomputer, etc., but the invention is not limited to this. , it may be performed by a so-called hard logic circuit.

[Field of Application] The present invention can be widely used in semiconductor wafer blowers.

[Brief explanation of drawings]

1 is an external view of a semiconductor wafer blower according to the present invention, FIG. 2 is a schematic plan view of its interior, and FIG. 3 is a schematic sectional view showing an embodiment of the air shower. The figure is a schematic sectional view showing one embodiment of the main part of the dustproof means. X-YTB...X-Y table, MS...microscope, CR
T...display device, ITV...imaging device, CAL
, CA2...cassette, PNL...operation panel, CT...
・Wafer chuck top, LS...Load stage, U
S...Unload stage, BC, Bl~B7...Round belt conveyor, As...Air shower, DC...Exhaust device, TB...Transfer arm, UC, LC...
Cover, UP... Pipe, UH, LH... Mitsumasa Tokuwaka, Patent Attorney representing Koana 0

Claims (1)

[Claims] 1. An air shower that blows impurity-free gas onto the surface of the semiconductor wafer to be measured is provided at a predetermined position on the semiconductor wafer transfer path, and before the start of the measurement, the semiconductor wafer is A semiconductor wafer prober characterized in that it cleans the surface of a semiconductor wafer. 2. The semiconductor wafer prober according to claim 1, wherein the gas is dry nitrogen. 3. The semiconductor wafer prober according to claim 1 or 2, wherein the air shower is provided at an upper part near the load position and within a movable range of the wafer chuck top. . 4. The semiconductor wafer prober is configured to automatically load the semiconductor wafer to be measured from the cassette to the wafer chuck top/FI1. Claims 1 and 2 are characterized in that they are equipped with an automatic loading/unloading mechanism for loading and unloading the semiconductor sea urchins, and are provided with dustproof means for shielding the entire transfer route to the semiconductor sea urchin from indoor dust. 3. The semiconductor wafer blower according to item 2 or 3.