JPH05243500A - Manufacture of high implantation resistor - Google Patents

Abstract

PURPOSE:To form a high implantation resistor of high precision, by forming a high implantation resistor layer in an N island by ion implantation, and forming thereon a shallow N-type diffusion layer having specified concentration by implanting N-type impurity ions. CONSTITUTION:A P-type high implantation layer 3 whose concentration is in the same order as the epitaxial concentration (10<14>-10<15>ions/cm<2>) is formed in an N island by ion implantation. A shallow N-type diffusion layer 4 whose concentration is in the order of 10<11>-10<12>ions/cm<2> is formed on the high resistance implantation layer 3 by implanting ions of N-type impurities like P and As. After an over-doped layer 5 and an N<+> diffusion layer are formed, the surface is covered with a protective film 1. Specified parts are opened and aluminum wiring 7 is formed. Influence upon electric charges in the protective film which is exerted by full power electrification and high temperature electrification is reduced by the effect of the N-type diffusion layer 4. Influence upon the high implantation resistor which is exerted by electric charges in the protective film is also reduced, and the resistance value scarcely changes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a sheet resistance of 3 kΩ /
□ The manufacturing method of the above high implantation resistance.

[0002]

2. Description of the Related Art In general, resistors in an IC have a structure in which P type diffusion is performed on N islands to form a large number of resistors in the same island. Although base diffusion is usually used for this P-type diffusion, in recent years IC
Therefore, a design that minimizes power consumption is required, and high resistance implanter resistors have come to be used frequently. Recently, implanter resistors having a concentration not much different from the epitaxial concentration have been used. The present invention has a sheet resistance of 3 kΩ, which is not significantly different from the epitaxial concentration.
/ Regarding the resistance of the implanter above □.

[0003]

The implantation resistance formed at a concentration not much different from the epitaxial concentration (usually 10 ¹⁴ to 10 ¹⁵ ions / cm ² ) is not a problem for resistors that do not require so much precision, but for example, a regulator The stability of the resistor used in the reference voltage circuit section of 1 is a problem. That is, in such implanter resistance, redistribution of charges in the surface protective film occurs according to the potential distribution due to full-power energization, high-temperature energization, and the like, which causes a change in resistance value over time that cannot be ignored. FIG. 3 schematically shows the state of redistribution of mobile ions in the protective film by BT (high temperature current test). In the figure, 1 is an oxide film (protective film), 2 is mobile ions in the oxide film 1, 3 is a P-type high resistance implantation layer,
Reference numeral 5 is a resistance contact overdoped layer, 6 is an N ⁺ diffusion layer that takes an island potential, and 7 is an aluminum wiring.
3A shows the state before BT, and FIG. 3B shows the state after BT. Since the resistance island is normally at the highest potential of the island, the redistribution of the mobile charge 2 in the protective film 1 is such that many negative ions are gathered in the N epitaxial portion and many positive ions are gathered near the lowest potential above the resistor. Redistribute. The implantation resistance of the lower layer is affected by the amount of ions collected on the upper side of the resistance, and the resistance value increases. It is an object of the present invention to obtain a high implantation resistance with a small change in resistance value due to full power energization and high temperature energization.

[0004]

The manufacturing method of the present invention is
A P-type high implantation resistance layer is formed on the island by ion implantation, and an N-type impurity such as P or As is ion-implanted on the upper portion of the high implantation resistance layer to have a shallow concentration of 10 ¹¹ to 10 ¹² ions / cm ² order. It is characterized in that an N type diffusion layer is formed.

[0005]

According to the above method, the N-type diffusion layer formed on the upper portion of the high implantation resistance reduces the influence of the high implantation resistance charges at the time of full power conduction and high temperature conduction on the charges in the protective film. The concentration of electric charges is alleviated, and the influence of electric charges in the protective film on the high implantation resistance is also reduced, so that the change in resistance value becomes negligible.

[0006]

EXAMPLE FIG. 1 schematically shows the structure of high implantation resistance according to the manufacturing method of the present invention. In the figure, the same reference numerals as those in FIG. 3 indicate the same or corresponding portions, and 4 indicates the concentration formed by ion implantation of N-type impurities such as phosphorus P or arsenic As on the high resistance implantation layer 3 of 10 ¹¹ to It is a shallow N-type diffusion layer of the order of 10 ¹² ions / cm ² . The number of mobile ions in the protective film is 7 × 10 ¹⁰ ions / cm ² . N
A P-type high-resistance implantation layer 3 having a concentration of the same order as the epitaxial concentration (10 ¹⁴ to 10 ¹⁵ ions / cm ² ) is formed on the island by ion implantation, and then N-type impurities such as phosphorus P or arsenic As are added. The concentration of 10 ¹¹ to 10 ¹² ions / cm ² is applied to the upper portion of the high resistance implantation layer 3 by ion implantation.
An N-type diffusion layer 4 having a shallow order is formed. After that, as in the conventional case, the overdoped layer 5 of the resistance contact is formed.
Then, an N ⁺ diffusion layer having an island potential is formed, the surface is covered with the protective film 1, a predetermined portion of the protective film 1 is opened, and an aluminum wiring 7 is formed.

The N-type diffusion layer 4 formed at the interface between the high resistance implantation layer 3 and the protective film 1 reduces the influence of full-power energization and high-temperature energization on the charges in the protective film, and The concentration of charges is relieved, and the influence of the charges in the protective film on the high implantation resistance is also reduced, so that the resistance value hardly changes. FIG. 2 shows the relationship between the concentration of the N-type diffusion layer and the output voltage fluctuation rate before and after BT when the high implantation resistance according to the present invention is used in the reference voltage circuit section of the regulator. In the case where the N-type diffusion layer 4 was not provided, the drift was 1.14%, but the concentration was 3 × 10 ¹² ions / cm ^2.
At 0.02%, and at a concentration of 4 × 10 ¹² ions / cm ² at 0.1.
The amount of drift is 36%, and it can be seen that if the concentration of the N-type diffusion layer 4 is set to an appropriate value, it can be suppressed within the range in which the fluctuation of the resistance value does not interfere.

[0008]

As described above, according to the present invention,
There is an effect that it is possible to suppress the change in the resistance value due to the high power conduction of the high implantation resistance and the high temperature conduction to a negligible degree, and it is possible to easily obtain the high precision implantation resistance.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing the structure of high implantation resistance according to the manufacturing method of the present invention.

FIG. 2 shows the concentration and B of the N-type diffusion layer when the high implantation resistance according to the present invention is used in the reference voltage circuit section of the regulator.
It is a graph which shows the relationship of the output voltage fluctuation rate before and behind T.

FIG. 3 is an explanatory view schematically showing a state of redistribution of mobile ions by BT in a conventional protective film having a high implantation resistance.

[Explanation of symbols]

1 Oxide Film 2 Mobile Ion 3 P-type High Resistance Implant Layer 4 N-type Diffusion Layer 5 Resistive Contact Overdoping Layer 6 Island-potential N ⁺ Diffusion Layer 7 Aluminum Wiring

Claims (1)

[Claims] 1. A first conductive type epitaxial layer or substrate having a sheet resistance of 3 kΩ / □ or more by ion implantation.
A second conductivity type high implantation resistance layer opposite to the conductivity type is formed, and a shallow first conductivity type diffusion layer having a concentration of 10 ¹¹ to 10 ¹² ions / cm ² order is formed by ion implantation on the high implantation resistance layer. A method for manufacturing a high implantation resistance, which comprises: