JPS63207164A - Thin-film resistor device - Google Patents

Abstract

PURPOSE:To inhibit the increase of, a resistor-pattern area or a chip area by forming a resistance element by a thin-film low resistor, in which a high resistance layer having high sheet resistance is arranged onto a resistance layer having low sheet resistance, and a thin-film high resistor consisting of the high resistance layer having high sheet resistance. CONSTITUTION:A resistance element is shaped by a thin-film low resistor A formed by disposing a high resistance layer 9 having high sheet resistance onto a resistance layer 8 having low sheet resistance and a thin-film high resistor B composed of the high resistance layer 9 having high sheet resistance. When the fundamental constitution is realized by the change of film thickness, resistor pattern shapes can be reduced in both a high resistance section and a low resistance section because the high resistance section is shaped in thin-film thickness and the low resistance section in thick film thickness, and an addition process by the formation, etc., of an interlayer insulating layer is removed because the low resistance section is formed in constitution in which only thick films and thin films are superposed continuously, thus largely simplifying processes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film resistor device, and more particularly to a thin film resistor device in which a thin film resistor is formed on a semiconductor integrated circuit chip.

[Conventional technology]

In general, a thin film resistor is formed as a single layer film using NiCr, Ta2N, or the like by vapor deposition or sputtering on an oxide film provided on a semiconductor substrate so as to have a predetermined sheet resistance value. Carbon thin film resistors are also known (see Japanese Patent Laid-Open No. 61-4270). Semiconductor integrated circuit devices usually require multiple resistance elements with multiple resistance values, so in the conventional method, NiCr or the like is formed on the entire surface of the substrate by vapor deposition or the like, and then various lengths are deposited to obtain the desired resistance value. After etching is performed to form a pattern with a certain height and width, wiring is then performed between the active element portion and the like within the same substrate.

[Problem that the invention seeks to solve]

However, according to the above conventional method, the sheet resistance of the thin film resistor is one type, so depending on the resistance value of the resistor required, the resistor pattern area becomes large (and the chip area increases). However, there is a problem in that it causes a decrease in yield and an increase in cost.

The present invention has been made in view of the above-mentioned problems when forming thin film resistive elements having different sheet resistance values on a semiconductor integrated circuit chip, and is capable of suppressing a significant increase in the resistor pattern area or chip area. The present invention provides a thin film resistor device that can be used.

[Means for solving problems]

The thin film resistor device of the present invention is a thin film resistor device in which thin film resistor elements having different resistance values are formed on an insulating film formed on the main surface of a semiconductor substrate in which an active element region is formed. The resistor element is formed by a thin film low resistance element formed by disposing a high resistance layer having a high sheet resistance on a low resistance layer, and a thin film resistor formed by the high resistance layer having a high sheet resistance. shall be.

The present invention will be explained in detail below. Generally, the resistance value (that is, sheet resistance) of a thin film changes depending on the film thickness, with a thin film having a high resistance and a thick film having a low resistance. The sheet resistance of a thin film also changes depending on the specific resistance of its constituent materials. The present invention
In addition to utilizing this property of sheet resistance, we can also change the multilayer or single layer structure on the same chip.
In addition, the principle that when the difference in resistance values of parallel resistances is large, the combined resistance is determined approximately by the resistance value of the low resistance element is used. Its basic structure is that, for thin film resistors, if a resistive layer with a high sheet resistance is placed on a resistive layer with a low sheet resistance, a parallel resistance is created and the desired low resistance is determined by the former resistive layer. On the other hand, for thin film high/low resistance elements, if the resistance layer itself with high sheet resistance is used, not only will the desired resistance value be obtained, but when the entire resistor is exposed, the high resistance layer will remain on the chip. Since the low resistance layer is exposed on the top surface and is masked, the entire top surface of the chip can be etched with one mask pattern and one type of etch lag agent in the same etching time, which has the advantage of avoiding an increase in the number of steps. occurs.

If the above basic configuration is realized by changing the film thickness, the film thickness will be thinner in the high resistance part and thicker in the low resistance part, so the shape of the resistor pattern can be made smaller in both cases, and the shape of the resistor pattern can be made smaller in both areas. Since it has a structure in which only films and thin films are successively stacked, there is no additional processing step such as forming an interlayer insulating layer, and the process can be greatly simplified.

Furthermore, if the above basic configuration is realized by using different materials, the thickness of the high sheet resistance layer stacked on the low sheet resistance layer can be arbitrary.

Furthermore, the basic configuration of the present invention can be realized by simultaneously changing the material and film thickness. An example is shown in FIG.

That is, an insulating film 2 is formed on the main surface of a semiconductor substrate 1 on which an active element region etc. are formed, a first resistance layer 3 of Ta2N or the like is formed thereon with a large thickness in a low resistance formation region, and then A second resistance layer 4 made of 5iCr or the like having a composition different from that of the first resistance layer 3 is formed on the entire surface with a thin film thickness, and then a second resistance layer 4 is formed on the entire surface except for the high resistance formation area and the low resistance formation area. The layer 4 is removed by etching, and necessary wiring/electrodes 5 are formed using A1 or the like.

In the above, an example of a high-resistance material with one layer of (al) and a low-resistance material with two layers was explained;
A configuration with more than one layer is also possible. Such a configuration (bl is the configuration (
Although the process is longer than Al, it has the advantage of making the resistor pattern area extremely small. In addition, on the same chip (
By implementing the configuration of at, (bl in different locations, it would be possible to orderly arrange a large number of thin film resistors with different resistance values, but with extremely small areas and approximately the same size, on a chip.

The present invention will be described below with reference to more preferred embodiments.

〔Example〕

Examples in which a thin film resistor is formed on a MOSLSI using this configuration are shown in FIGS. 2 to 6. As shown in Figure 2,
P-type silicon substrate 1, P-type channel stopper 2, L
After forming an OCO5 oxide film 3, a gate oxide film 4, a PolySi wiring 5, a source and drain N-type diffusion layer 6, and a BPSG reflow film 7 by a normal MO5LSI process, using Ta2N, the sheet resistance is, for example, 110Ω/hole. A low resistance layer 8 is formed on the BPSG reflow film 7. Next, as shown in FIG. Using photoetch technology, thin film low resistance A and thin film high resistance B are formed as shown in FIG.
form.

Note that when forming this thin film low resistance A, the low resistance layer 8 which is wider than the pattern of the high resistance layer 9 is formed in advance in the step shown in FIG. 2, and the pattern of the high resistance layer 9 is changed in the step shown in FIG. After coating, the exposed portion of the low resistance layer 80 is removed by machining and notching using the resistance layer 9 as a mask, thereby obtaining a thin film low resistance element A in which the upper and lower resistance layers 8.9 are completely overlapped. However, the effects of the present invention can be obtained even if the thin film low resistance element A is wide at the bottom and narrow at the top, or vice versa.

Further, a lift-off process as shown in FIG. 7 can also be employed at the stage of FIG. 3. That is, the mask 14 has etching selectivity with respect to the resistive layer 9.
After forming resistor N9 to be thicker than resistor N9 in the area where resistor 9 is not formed, the material of resistor layer 9 is deposited on the entire surface and the mask is removed by etching to obtain the structure shown in FIG.

Next, source drain contact holes 11.11
' is formed as shown in Fig. 5, and by forming the A/wiring 12, two types (100 Ω/hole,
An MO3LSI can be formed in which thin film resistors A and B with a sheet resistance of 1000Ω/unit are integrated.

According to the above embodiment, the high resistance part (8) is made of a thin film material with a high sheet resistance, so the pattern shape can be made small, and the low resistance part (8) is made of a film with a high sheet resistance and a thin film with a high sheet resistance. Since it is composed of a parallel resistor consisting of a film with a low sheet resistance, if there is a large difference in the sheet resistance values of each, the sheet resistance value will be the same as that of the film with a low sheet resistance.

For example, if R,=110Ω/portion and R,=1 are set to Ω/portion, the combined sheet resistance of the low resistance part will be about 100Ω/portion, and a small pattern shape can be obtained like the high resistance part.

〔Effect of the invention〕

According to the present invention, the area of the thin film resistor is reduced, thereby reducing the area of the chip, and the process of forming the thin film resistor is simple, so that the size and cost of the thin film resistor device can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the thin film resistor device of the present invention, and FIGS. 2 to 7 are manufacturing process diagrams of the thin film resistor device. l...P-type silicon substrate, 8...low resistance layer, 9
...High resistance layer. Figure 2 Figure 4 Figure 6

Claims (1)

[Claims] 1. In a thin film resistor device in which thin film resistive elements having different resistance values are formed on an insulating film formed on the main surface of a semiconductor substrate in which an active element region is formed, sheet resistance is low. The resistance element is formed by a thin film resistor formed by disposing a high resistance layer having a high sheet resistance on a resistance layer, and a thin film high resistance object formed by the high resistance layer having a high sheet resistance. Thin film resistor device.