JPH04305921A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To measure even the comparatively small quantity of charge quantitatively, and to implant ions uniformly extending over the whole semiconductor substrate by implanting impurity ions to the semiconductor substrate and measuring the resistance value of a resistor composed of polycrystalline silicon formed. CONSTITUTION:A plurality of resistors 3 consisting of polycrystalline silicon are formed onto a semiconductor substrate 1 for measuring the quantity of charge through an oxide film 2. When impurity ions are implanted onto the semiconductor substrate 1, the resistance values of the resistors 3 are increased by charging. The resistance values differ by the positions of each resistor 3. Since the degree of variability of resistivity in a region, in which the breakage of a gate oxide film may exceed 0%, is approximately 15%, even the quantity of charge, which do not break the gate oxide film, can be measured sufficiently by the degree of variability of the resistance value through a conventional measuring method. Accordingly, impurity ions can be implanted uniformly to the semiconductor substrate without being affected by the quantity of charges.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for measuring the amount of charge on a semiconductor substrate during an ion implantation process.

0002

2. Description of the Related Art Conventionally, the amount of charge on a semiconductor substrate during the ion implantation process in the manufacture of semiconductor devices has been measured as shown in FIG. It was carried out using multiple patterns consisting of. The charge 6 of the implanted ion beam is accumulated and charged in the gate oxide film 4, and when the amount of charge exceeds a certain amount, a discharge occurs in the gate oxide film 4, destroying the gate oxide film 4. The breakdown of the gate oxide film 4 was detected by applying a voltage to the aluminum electrode 5, and the amount of charge was measured based on the rate of breakdown of the gate oxide film 4.

When charges 6 are accumulated on the semiconductor substrate, the ion beam is bent by the Coulomb force, so that the amount of impurity implanted cannot be made uniform. Therefore, by measuring the amount of charge using a semiconductor substrate for measuring the amount of charge, it is possible to take measures to prevent charging, such as using an electron shower, as necessary. That is, as shown by the broken line B in FIG. 3, the current value of the electron shower is controlled to such an extent that the gate oxide film is not destroyed under the specified ion implantation conditions (destruction rate 0%), and the influence of charging is eliminated. Can be done.

0004

[Problem to be Solved by the Invention] As described above, the measurement of the amount of charge on a semiconductor substrate during the ion implantation process in semiconductor device manufacturing is difficult because charge is accumulated in the gate oxide film and the accumulated charge exceeds a certain amount. Since this method takes advantage of the fact that the gate oxide film is destroyed by discharge when the gate oxide film is damaged, it is not possible to measure the amount of charge that does not lead to the destruction of the gate oxide film using this conventional method. Particularly in recent years, with the miniaturization of semiconductor devices, there has been a growing demand for uniformity in the amount of ion implantation, and even a small amount of charge can make the amount of ion implantation uneven, causing variations in the characteristics of semiconductor devices. .

[0005]

[Means for Solving the Problems] A method for manufacturing a semiconductor device of the present invention includes a step of ion-implanting impurities into a semiconductor substrate, and a low-resistance antibody made of polycrystalline silicon formed on the semiconductor substrate after the ion implantation. The method includes the step of detecting the amount of charge on the semiconductor substrate due to the ion implantation by measuring the amount of charge on the semiconductor substrate.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a semiconductor chip for explaining one embodiment of the present invention.

As shown in FIG. 1, a plurality of low antibodies 3 made of polycrystalline silicon are provided on a semiconductor substrate 1 for measuring the amount of charge with an oxide film 2 interposed therebetween. When impurity ions are implanted onto this semiconductor substrate 1, the resistance value of the resistor 3 increases due to charging, as shown, for example, by broken line A1 in FIG. The resistance value differs depending on the position of each resistor 3.

When a prescribed amount of impurity is ion-implanted into the semiconductor substrate 1, the resistance value of the resistor 3 becomes high as shown by the broken line A1 in FIG. It is possible to suppress the increase in resistance value, that is, the amount of electrification.

[0009] The relationship between the rate of change in resistance value and the amount of charge is as follows:
As shown by the solid line A in FIG. 3, it can be seen that the fluctuation rate of the resistance value in the region where the destruction rate of the conventional gate oxide film tends to exceed 0% is about 15%. Therefore, as shown in FIG. 3, the amount of charge that does not destroy the gate oxide film using conventional measurement methods can be sufficiently measured by the rate of change in resistance value. Therefore, for example, by controlling the current value of the electron shower so that the fluctuation rate of the resistance value is 10% or less, impurity ions can be uniformly implanted into the semiconductor substrate without being affected by the amount of charge. .

0010

[Effects of the Invention] As explained above, the present invention measures the amount of charge caused by ion implantation in the ion implantation process by measuring the resistance value of a resistor made of polycrystalline silicon formed on a semiconductor substrate. , relatively small amounts of charge can be measured quantitatively. This makes it easy to control the amount of charge, which has the effect of reducing variations in the characteristics of semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor chip for explaining one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a semiconductor chip for explaining a conventional example.

FIG. 3 is a diagram showing the relationship between the amount of charge, the rate of change in resistance value, and the rate of destruction of the gate oxide film, for explaining the embodiment and the conventional example.

FIG. 4 is a diagram showing the relationship between the position of a resistor and the resistance value of the resistor after ion implantation.

[Explanation of symbols]

1 Semiconductor substrate 2 Oxide film 3 Resistor 4 Gate oxide film 5 Aluminum electrode 6 Charge

Claims (1)

[Claims] 1. A step of ion-implanting impurities into a semiconductor substrate, and charging the semiconductor substrate due to the ion implantation by measuring the resistance value of a low antibody made of polycrystalline silicon formed on the semiconductor substrate after the ion implantation. A method for manufacturing a semiconductor device, comprising the step of detecting the amount.