JPS61270840A - Temperature measurement of semiconductor wafer - Google Patents

Abstract

PURPOSE:To detect the wafer temperature by means of measuring the elongation due to thermal expansion of a semiconductor. CONSTITUTION:An OF 14 of a wafer 1 is placed to a quartz pin 9 for alignment and then a furnace 8 is supplied with current to heat the wafer 1. The wafer 1 is elongated to move a core 4 of a differential transformer through the intermediary of a quartz bar 2. At this time, a coil 5 and an elongation detector 11 output the displacement amount of core 4 as an electric signal. A bearing 3 facilitates sliding action of the quartz bar 2 while a spring 6 thrusts the bar 2 at specified pressure. A base 7 is a water-cooled metallic plate. Any detected elongation DELTAL as a signal of length LO at 20 deg.C is inputted from a length input circuit 13 to a calculation circuit 12 to measure the wafer temperature reversely making reference to the temperature corresponding to the degree of elongation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes the fact that semiconductor wafers expand due to heat, and is a method for determining the temperature at that time by detecting the expansion of the semiconductor wafer relative to the temperature. Currently, there are the following methods for directly measuring the temperature of a wafer.

■Method of measuring temperature by attaching an extremely thin thermocouple to the wafer.

■A method of measuring the color temperature and total radiation amount of the light radiated directly from the wafer using an optical pyrometer, etc.

The above method is common, but first, the method (2) has drawbacks such as the problem of contamination due to the use of thermocouples and adhesives, and the time required for installation.

Next, regarding (■), when heating at high speed, a radiant furnace is used to raise the temperature.
Generally, the infrared rays generated by the sensor are converted into electrical signals using semiconductor sensors, which are then converted into temperature.

The disadvantage is that the amount of light radiated by the furnace is relatively greater than the amount of light radiated by the wafer itself, so that sufficient accuracy cannot be obtained. In contrast to such methods, the present invention is a method in which the radial thermal expansion of the ridged semiconductor wafer is detected using a differential transformer or the like, and the expansion is converted into temperature.

The elongation of a silicon wafer with respect to temperature is 2
If the length at 0'C is LO and the elongation is ΔL, -
As an example, at 127°C ΔL/LO=0.0033%527°C
At ΔL/LO=0.181 coefficient 1127'C, ΔL/
A value of LO = 0.448 inches could be determined using an inflatable needle.

Further, between these temperatures, the material expanded monotonically, and no contraction was observed. Therefore, if ΔL and LO are input, the temperature of the semiconductor wafer can be determined by calculating ΔL/Lo and inversely referring to the temperature corresponding to the elongation rate.

To explain this aspect, the semiconductor wafer = (1) has a quartz bone pin (9), two quartz guide pins (1 oa
) (10b) and the quartz detection rod (2).
) is held in 1.

The orientational flat part α of the wafer is aligned with the pin (9) of the quartz support.

Electric current is passed through the furnace (8) and heat is supplied from the heater to the semiconductor wafer (1). At this time, the semiconductor wafer (1) stretches as the temperature rises, moving the core (4) of the differential transformer via the quartz detection rod (2). At this time, the coil (5) of the differential transformer and the elongation detection circuit ←υ output the amount of movement of the core (4) as an electrical signal.

The sliding bearing (3) serves to hold and smooth the movement of the quartz detection rod (2) and the like at this time.

The spring (6) serves to press the quartz detection rod (2) against the wafer with a certain force.

The conduction space plate (7) is made of water-cooled metal such as aluminum having high thermal conductivity.

The elongation △L output from the elongation detection circuit υ is output from the arithmetic circuit (12) by the signal LO input from the length input circuit (13).
1 performs the calculation and outputs it.

As an example of the present invention, a calibrated West Meru-Alumel thermocouple is attached to a 5-inch silicon wafer with an alumina adhesive,
When compared by raising the temperature at 50°C to 1000°C,
Agreement was achieved within a 10'C temperature range.

[Brief explanation of drawings]

Figure 1 is a side view of the present invention.

Claims (1)

[Claims] Temperature is detected by utilizing the thermal expansion of a semiconductor wafer and measuring the elongation of the wafer. Semiconductor manufacturing equipment uses this detected temperature.