JPH0224574A - Measuring method of microscopic distribution of specific resistance of semiconductor - Google Patents

Abstract

PURPOSE:To shorten a measuring time in a large degree by using a set of probes in the number of (nXm+1) and analog multiplexers provided in the number corresponding to that of the probes. CONSTITUTION:Input terminals are connected with eight probes corresponding thereto, and a guard electrode is connected with an earth probe, while an electrode at the rear is connected to a power source. When a channel selection input is given from a computer, one of 1 to 8 channels is energized to electrify one probe, and a resistance at one position on a wafer is measured by an ammeter 6. A resistance at a corresponding position is measured by switching the channel. Accordingly, points in the number of (n)X(m) are measured without transfer of the wafer. By this method, a measuring time is shortened in a large degree.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for measuring minute distribution of semiconductor resistivity.

[Prior Art] A measurement method called the three-electrode guard method is used to measure the minute distribution of semiconductor resistivity, and the method is as follows.

In FIG. 3, 1 represents a semiconductor wafer, 2 represents ohmic electrodes formed on one side of the wafer with a fixed size (e.g., 70 μm in diameter) and regular intervals (e.g., 100 μm) in the vertical and horizontal directions, and 3 represents these ohmic electrodes. This is an ohmic guard electrode that surrounds the electrode 2. Further, 4 is an ohmic electrode uniformly formed on the opposite surface.

At the time of measurement, connect the ohmic electrode 4 to the DC power supply 5,
The negative side of the DC power source 5 is grounded, the probe 7 is grounded via the ammeter 6, the probe 8 is grounded, the probe 7 is brought into contact with the electrode 2, the probe 8 is brought into contact with the guard electrode 3, and the probe 7 is brought into contact with the electrode 2. 2 and the guard electrode 3 are held at the same potential, and the current ■ is measured.

At this time, the specific resistance ρ of the microcylindrical body under the electrode l is expressed by the following equation.

However, " is the radius of the electrode 1, t is the thickness of the wafer, ■ is the applied voltage, and ■ is the current.

(The above method is described in Japanese Journal
of App-ed Physlcs, 1lo1
．． 23. August 1984. PP, LGO2-L
Referring to GO5, 6) Therefore, according to the above method, two tree probes were used and an autoprober was used to obtain the in-plane distribution of resistivity.

[Problem to be Solved] However, for example, if the in-plane distribution within a 40wm x 40mm area is 0. Im■ 400X when measured with Bifuchi
It is necessary to perform a constant determination of 400=IGO, 000 points, and the wafer must be moved the same number of times, which takes too much time.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above problems, and the conventional three-terminal guard method can be used.
However, there is a method for measuring the minute distribution of semiconductor resistivity using a set of n×m probes consisting of m n-channel analog multiplexers each connected to n probes, and one earth probe. .

The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 1 shows the structure of a probe set used in the present invention, in which each n probe P is connected to m n-channel analog multiplexers, forming an n×m probe set. Including that and 181 earth blowers, total n×m+1
It consists of several probes.

The pattern of the guard electrode (ground electrode) surrounding the electrode is the third
As shown in the figure, since the entire surface is continuous, only one earth probe E is required. The n×m probes P are formed to exactly fit the electrode circular pattern shown in FIG. Further, the plurality of probes P are formed as a sheet or as electrodes protruding from both sides of the plate surface.

FIG. 2 shows an 8-channel analog multiplexer as an example. ■、2. ...8 inlet terminals and the corresponding eight probes 7 (Fig. 3) are connected, the guard electrode 3 is connected to the earth probe E, and the electrode 4 on the back side is connected to the power source 5. Connected to ground.

In this state, if a channel selection input is given from the computer, one of channels 1 to 8 will be energized, one probe 7 will be energized, and the ammeter 6 will measure the resistance at one position on the semiconductor wafer. By switching channels, the resistance at the corresponding position can be measured. If m n-channel analog multiplexers are used, the resistance can be measured at n x m positions on the semiconductor. , and the distribution of resistivity becomes clear.

When using an n-channel analog multiplexer,
As shown in FIG. 2, the outputs from each analog multiplexer are connected to join before the ammeter 6, so only one ammeter is required.

According to the present invention, since n×m points can be measured without moving the wafer, the measurement time is significantly shortened. 1
The time required to maintain the wafer constant is the sum of the time actually applying a voltage and measuring the current and the time the wafer is moving, but this moving time is significantly reduced.

[Example] A total of 65 probe sets including a G411J probe with n=8 and m=8 and one earth probe were created, and an area of 81 m x 3 sn on the wafer was measured.

In the case of the conventional method using two probes, it took about 65 minutes to measure, but in the case of the present invention, the measurement time was significantly shortened to about 17 minutes.

[Effects of the Invention] As explained above, by using a set of (n×m+1) probes and a corresponding number of analog multiplexers as shown in FIG. 1, the measurement time can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the probe arrangement of the present invention. FIG. 2 is an explanatory diagram of measurement using an analog multiplexer. FIG. 3 is an explanatory diagram of the three-terminal guard method and the probe arrangement of the conventional method. 1... Semiconductor wafer, 2... Ohmic electrode, 3...
...Guard core pole, 4...Ohmic electrode (solid electrode)
, 5... DC power supply, 6... Ammeter, 7.8... Probe. Input of the nguy/name Lua of the 夷子 mko to the mouth 2 maruna brexa to the ear and half innel

Claims (1)

[Claims] (1) In the three-electrode guard method for measuring the minute distribution of specific resistance of semiconductor wafers, a set of n×m probes consisting of m n-channel analog multiplexers each connected to n probes and one earth probe are used. A method for measuring minute distribution of semiconductor resistivity, characterized in that it is used.