JP5148917B2 - Semiconductor wafer test method - Google Patents

Description

  The present invention relates to a method for testing a semiconductor wafer, and more particularly to a method for confirming a heat distribution state during heat treatment in a vacuum chamber of a semiconductor wafer used in the manufacture of an IC chip or the like.

In the manufacturing process of an IC chip, there is a step of heat-treating a semiconductor wafer as a material in a plasma atmosphere in a vacuum chamber. Prior to performing this heat treatment step, a dummy, that is, a test wafer is placed in a vacuum chamber, It is practiced to actually measure the heat distribution of each part of the wafer in the atmosphere. The test wafer is the same as that actually heat-treated.
Japanese Patent Application No. 2004-340067 None

  For this heat distribution measurement, a sheet-like temperature measurement piece is prepared on which a temperature-sensitive color former that irreversibly develops color at a specific preset temperature is fixed on a substrate. A plurality of sheets are affixed to a desired part such as a central part, heat-treated in a plasma atmosphere in a vacuum chamber, and then the color development state of each temperature measurement piece affixed to the wafer body is confirmed. In this way, the wafer body, which is the object of temperature measurement, is placed in the plasma atmosphere of the vacuum chamber. However, a discharge phenomenon frequently occurs in the plasma atmosphere, and the temperature sensitive color body is damaged by electric shock during discharge. In many cases, the temperature measurement result cannot be displayed correctly.

  In addition, in temperature sensitive color bodies that measure temperatures in a high temperature region of about 300 ° C. or more, in order to provide heat resistance, heavy metals such as cobalt and nickel are often included in the components, and When the warm color former is left in the plasma atmosphere, these heavy metals are gasified by plasma discharge, and this gas diffuses into the vacuum chamber and contaminates it, and the contaminated vacuum chamber is the original heat treatment of the wafer. There was also a serious problem that it could not be used for work.

  The present inventor conducted research to solve the above problems caused by the plasma discharge phenomenon in the temperature distribution measurement work performed prior to the plasma processing in the vacuum chamber of the semiconductor wafer, and as a result, avoided damage due to the plasma discharge. A test wafer capable of preventing contamination in the vacuum chamber by heavy metal gas was proposed as Japanese Patent Application No. 2005-241973.

  This test wafer fixes a temperature display body that changes from a cloudy opaque state to a transparent or translucent state when a predetermined set temperature is reached at a desired position on the wafer body, and heat-resistant on it. A test wafer is formed by covering with a conductive resin layer.

  In this test wafer, when it is put into a vacuum chamber and a test heat treatment is performed, the temperature display body fixed to each part of the wafer main body is at the time when a predetermined set temperature is exceeded. , The powdered chemical substance melts, and the white turbidity until then becomes transparent, so that the color of the surface of the substance on which this temperature indicator is applied and fixed can be seen through. The fact that the set temperature is exceeded is displayed externally due to the change.

  Therefore, if a large number of the temperature display bodies are fixed to each part of the test wafer body, the temperature distribution of each part of the wafer body can be known in detail. At this time, since the temperature display body is covered with a heat-resistant resin layer, even if plasma discharge occurs in the vacuum chamber, the temperature display body itself is not directly exposed to electric shock, and the temperature display function is provided by plasma discharge. There will be no madness.

  Moreover, since the temperature display body is covered with a heat-resistant resin layer, even if the temperature display body contains heavy metals such as nickel and cobalt, these heavy metals are gasified and diffused into the vacuum chamber. There is no risk of contamination, and temperature measurements in heavy metals such as nickel and cobalt must be used. Temperature measurement in a high temperature range can be performed more safely, and has superior functions compared to conventional ones. It is.

  However, with the increasing functionality of semiconductor wafers, there is a strong demand in recent years to increase the heating temperature in the vacuum chamber, and there are cases where heating is performed at ultra-high temperatures such as 500 ° C. or higher, or 1000 ° C. or higher. The body is required, the amount of heavy metals added tends to increase, and the heat resistant resin layer for preventing diffusion of heavy metal gas into the vacuum chamber is required to be stronger. However, heat-resistant resin layers that can withstand high temperatures and prevent the scattering of heavy metal gases are often opaque due to the relationship of the materials that make up the heat-resistant resin layers, and visual changes in temperature indicators can be confirmed through this heat-resistant resin layer. In some cases, it could not be done. The present inventor conducted research to solve the problem related to this point, and as a result, it was possible to reliably measure the temperature distribution at an ultra-high temperature of, for example, 1000 ° C. or higher without diffusing heavy metal gas into the vacuum chamber. We have succeeded in developing an innovative semiconductor wafer test method, and are proposed here as the present invention.

A temperature indicating material that changes from a cloudy opaque state to a transparent or translucent state is attached to a desired location on the surface side of a transparent or translucent test semiconductor wafer at a predetermined preset temperature. After coating a fouling film to prevent gasification of the temperature indicating material, the semiconductor wafer is placed in a heating vacuum chamber and subjected to a predetermined heat treatment. Then, the semiconductor wafer is taken out of the chamber, and the semiconductor The above problem was solved by visually recognizing the change state of the temperature indicating material from the back side of the wafer through the thickness thereof, thereby knowing the temperature distribution state of each part of the semiconductor wafer under plasma discharge.

  In this test method, since the change of the temperature indicating material is seen through from the back side of the semiconductor wafer, the protective film that prevents gasification of the temperature indicating material does not need to be transparent at all, and the material is not selected. A strong fender can be used, and a heating test at an extremely high temperature, which was difficult in the past, can be carried out without any problems.

  The greatest feature exists in that the change of the temperature indicating material is viewed from the back side of the semiconductor wafer through the thickness of the semiconductor wafer.

Hereinafter, an embodiment of a semiconductor wafer test method according to the present invention will be described with reference to the drawings. As a semiconductor wafer used for the test, a transparent or translucent material that can be seen through in the front and back directions is used. Then, on the surface side of the main body 1 of the semiconductor wafer, as shown in FIG. 1, a desired temperature indicating material 2 which changes from a cloudy opaque state to a transparent or translucent state when a predetermined temperature is reached is desired. Adhere with a pattern. The temperature indicating material 2 itself is the same as that of Japanese Patent Application No. 2005-241973, and is white turbid at room temperature in which a powder of a solid chemical substance such as wax that melts at a preset temperature and a binder are mixed. It is an opaque material and is attached in a desired pattern on the surface side of the main body 1 of the semiconductor wafer by a technique such as silk screen printing.

As shown in FIG. 2, the surface of the semiconductor wafer to which the temperature indicating material 2 is fixed has excellent heat resistance, and heavy metals in the temperature indicating material 2 are gasified and diffused even at an ultra-high temperature. A fouling film 3 that can prevent the above is coated. This fender film 3 is generally opaque, and the temperature indicating material 2 cannot be visually recognized through this fender film 3.

  In this way, the test semiconductor wafer coated with the temperature indicating material 2 on the surface side and coated with the fender film 3 is placed in a vacuum chamber for heating, and a predetermined heat treatment with plasma discharge is performed. Thereafter, the heated semiconductor wafer is taken out of the chamber, and as shown in FIG. 3, the change in the temperature indicating material 2 after heating is visually confirmed through the thickness of the back surface of the semiconductor wafer. Know the temperature distribution of each part under plasma discharge.

  In this test method, since the change of the temperature indicating material is viewed through the back side of the semiconductor wafer, the anti-gasification film need not be transparent at all, and since the material is not selected, it is more robust. A film can be used, and a heating test under an extremely high temperature, which has been difficult in the prior art, can be carried out without any problem.

  It can be used in the field of semiconductor manufacturing.

The perspective view of the state which applied the temperature indicating material to the semiconductor wafer surface tested by the testing method of the semiconductor wafer concerning this invention. Similarly, the perspective view of the state which coated the fender film on it. The perspective view of the condition at the time of confirming the condition of the heat distribution of each part after the heating in a vacuum chamber is completed.

1 Main body 2 Temperature indicating material 3 Antifouling film

Claims (1)

  At the desired location on the surface side of the test semiconductor wafer that is transparent or translucent, attach a temperature indicating material that changes from a cloudy opaque state to a transparent or translucent state at a specific temperature set in advance. After coating a fouling film that prevents gasification of the temperature indicating material, this semiconductor wafer is placed in a vacuum chamber for heating, and after performing a predetermined heat treatment, the semiconductor wafer is taken out of the chamber, and the semiconductor wafer A method for testing a semiconductor wafer, characterized in that the change of the temperature indicating material is visually recognized from the back side of the wafer, and the temperature distribution state of each part of the semiconductor wafer under plasma discharge is thereby known.

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