JP2524049B2 - Semiconductor integrated circuit and manufacturing method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Po whose resistance value is controlled.
The present invention relates to a semiconductor integrated circuit having a ly-Si resistor and a manufacturing method thereof. 2. Description of the Related Art In recent years, semiconductor integrated circuits have been highly integrated and have high performance. Therefore, a method of adjusting the resistance value of the resistor formed in the semiconductor integrated circuit while measuring the entire characteristics after the completion of the semiconductor integrated circuit has come to be used. A laser is used to adjust the resistance value. This method is similar to the method generally used for adjusting a thick film or thin film resistor formed on a ceramic substrate. That is, as shown in FIG. 1, a resistor 3 formed of tantalum nitride, chromium silicon, nichrome, polysilicon, or the like, which is insulated by a SiO ₂ film 2 or the like on a Si substrate 1, is irradiated with laser light 4 By removing a part of the resistor 3, the resistance value between the electrodes 5 and 5'at both ends of the resistor 3 is adjusted. Alternatively, as shown in FIG. 2, the resistor 3 is subjected to spot processing (processing trace 6), or, as shown in FIG.
A method of adjusting the resistance value between 5'has been used. However, in all of these methods, a part of the formed resistor is removed and adjustment is performed by increasing the resistance value from the initial value. When high, it was impossible to adjust it low. Further, since the resistance value is adjusted after the semiconductor integrated circuit is completed, the entire circuit is coated with a passivation film, and if a part of the resistor is removed, the passivation film is also removed, and the reliability is improved. From the viewpoint, it was necessary to coat the passivation film again. The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to increase and decrease the resistance value, and to prevent the passivation film from being damaged, which is a semiconductor integrated circuit. It is to provide a resistor inside and a method of adjusting its resistance value. According to the present invention, polysilicon doped with impurities is used as a resistor, and impurities of the same type as the impurities doped in the polysilicon resistor are polysilicon-heated by laser heating. By diffusing into the resistor to reduce the resistance value, or by diffusing different types of impurities to increase the resistance value, the resistance value is reduced / increased and adjusted to the necessary (optimal) resistance value. It is a thing. The present invention will be described below with reference to the drawings. FIG.
FIG. 7 shows a resistor formed in the semiconductor integrated circuit according to the present invention. 4A is a plan view and FIG. 4B is a cross-sectional view thereof, a Poly-Si resistor 11 in which an n-type impurity is doped is formed on the Si substrate 1 through the SiO ₂ film 2. Both ends thereof are connected to other elements (diodes, transistors, etc.) through Al wirings 12 and 12 '. An SiO ₂ film 13 is formed on the Poly-Si resistor 11.
Poly-S doped with n-type impurities via
i layer 14 and Po doped with p-type impurities
The ly-Si layer 15 is formed in an island shape, and SiO ₂ is formed thereon.
S as layer 16 and final passivation film 17
A film composed of an iO ₂ layer, a Si ₃ N ₄ layer, or both is formed. Generally, the Poly-Si resistor 11 includes 500 to 500 doped with phosphorus as an n-type impurity.
A sheet resistance value of several tens of Ω / □ to several hundreds of K with a thickness of 0Å
Ω / □ is formed. The SiO ₂ layer 13 has a film thickness of 5
00-3000Å, P doped with n-type impurities
The poly-Si layer 14 has a thickness of 500 to 5000 Å and Po
The Poly-Si layer 15 having an impurity concentration higher than that of the poly-Si resistor by one digit or more, and having a thickness of 500 to 5000 Å doped with p-type impurities has the same impurity concentration as the Poly-Si resistor 11. I have it. Also,
The SiO ₂ layer 16 formed thereon has a thickness of 500 to 3
000Å, final passivation film 17 is 1000
The thickness is ~ 4000Å. Here, as a sample, the Poly-Si resistor 11 is phosphorus-doped Poly-Si and the film thickness is 3000 Å.
A sheet resistance value of 10 KΩ / □ formed with a width of 5 μm and a length of 45 μm was used. Poly-Si shown in FIG.
The resistor is irradiated with laser using the optical system shown in FIG. That is, the optical system shown in FIG. 5 uses the variable slit 2 capable of shaping the laser light 21 oscillated by the laser oscillator (not shown) into any size, and the resistor 11 and the Poly-Si layer formed thereon. The resistor 11 and the Poly-Si layer 1 formed on the resistor 11 which is formed in a rectangular shape that matches the irradiation shape of 14 or 15 and is placed at a position where the real image of the variable slit 22 is formed by the objective lens 23.
4 or 15 is transmitted through the insulating films 16 and 17 and is focused and irradiated at the reciprocal of the magnification of the objective lens 23. The insulating films 16 and 17 and the like are omitted in FIG. The laser oscillator uses an N ₂ laser pumped Dye laser, and the laser light has a wavelength of 510 n.
m, and the pulse width is 6 ns in half width. Here, the Poly-Si resistor shown in FIG. 4 is doped with an n-type impurity on the poly-Si resistor.
P is separately provided via the ly-Si layer 14 and the Poly-Si layer 15 doped with p-type impurities.
A laser was applied to the 15 μm-long portion of the oli-Si resistor 11. The relationship between the laser irradiation pulse number and the resistance value at this time is shown in FIG. The resistance value, which was about 90 KΩ before laser irradiation, decreases with the number of irradiation pulses as shown by ◯ when the n layer 14 is irradiated, and becomes constant at 61 KΩ after about 50 pulses, and when irradiating the P layer 15, it becomes ●. As shown, it became constant at 150 KΩ in about 70 pulses. (In FIG. 6, the resistance value for every 10 pulses is plotted.) From this, when the laser irradiation position is selected and the laser irradiation is performed while measuring the resistance value, the time point when the predetermined resistance value is obtained. By stopping the irradiation at, the resistance value which was initially 90 KΩ was changed to 61
It will be possible to adjust to any resistance value between KΩ and 150 KΩ (although it varies stepwise rather than continuously due to pulse irradiation). The irradiation laser power density at this time is 1 to 2 pulses, and the Poly-Si resistor 11 (on the upper Po
It was set to 1/3 of the power density at which the removal processing can be performed on the ly-Si layer 14 or 15).
Even after 100 pulses of irradiation, no damage or trace was found on the passivation film 17. In the embodiments described above, the resistance value adjustment range is -32% to + 66% with respect to the initial value. This adjustment range covers the n-type and Poly-Si resistor 11 covered type. Pol doped with p-type impurities
Obviously, it can be changed by changing the areas of the y-Si layers 14 and 15. That is, by increasing the area of the n-type Poly-Si layer 14 on the Poly-Si resistor 11, the resistance value lowering range is expanded, and by increasing the area of the p-type Poly-Si layer 15, the resistance value is increased. It is clear that the range will be expanded. Further, in this embodiment, as the Poly-Si resistor 11, a Poly-Si resistor 11 doped with an n-type impurity is used.
-Si was used, but P doped with p-type impurities was used.
It is also possible to use oli-Si as a resistor. When an n-type Poly-Si resistor is used, the n-type Poly-Si layer 1 above it is used.
Form a PSG (phosphorus glass) layer instead of 4 or p
In the case of using a type-type Poly-Si resistor, a BSG (pollon glass) layer may be formed instead of the p-type Poly-Si layer 15 to arbitrarily increase and decrease the resistance value. Is clear. Further, in this embodiment, the N ₂ laser pumped Dye laser is used as the laser beam 21, but the present invention is not limited to this, and the passivation film 1 is used.
It is obvious that any material that can heat Poly-Si at a wavelength that transmits 6, 17 is applicable regardless of continuous oscillation or pulse oscillation. Next, another embodiment will be described. As shown in FIG. 7, with respect to the Poly-Si resistor 11 shown in FIG. 4, the laser irradiation region 25 has a length of 2 μm, and the n-type Poly-Si layer 14 or p is formed under the laser irradiation conditions described above. 70 pulses are irradiated through the type Poly-Si layer 15 and then moved by 2 μm to make a laser irradiation region 25 ′.
The irradiation of 70 pulses was repeated. This allows
When the irradiation is performed through the n-type Poly-Si layer 14, the resistance value is gradually reduced, and the p-type Poly-Si layer is irradiated.
When irradiated through layer 15, there was a gradual increase.
That is, as shown in FIG.
With pulse irradiation once), with an initial value of 9
What was 0 KΩ is the n-type Poly-Si layer 14
When it is radiated via γ, it decreases by about 4 KΩ as indicated by ◯, and when it is radiated to 62 KΩ with 7 times of irradiation (extension of the irradiation region is 14 μm), and when it is radiated through the p-type Poly-Si layer As indicated by ●, increases by about 8 KΩ,
146 in 7 times of irradiation (extension of irradiation area is 14 μm)
KΩ changed. From this, the Poly-S shown in FIG.
By selecting the irradiation position for the i-resistor, it is possible to arbitrarily increase or decrease the initial resistance value. Next, FIG. 9 shows another embodiment of a resistor which can increase / decrease the resistance value according to the present invention. A Poly-Si resistor 27 doped with n-type impurities is formed between the Al electrodes 12 and 12 '. The n-type Poly-Si resistor 27 has a so-called "ladder step" shape in which a plurality of resistors are arranged in parallel, and is a ladder step resistor except for a portion having the longest distance as a resistor. A high resistance portion 30 is formed in a part of the area. The high resistance portion 30 is a Poly-Si having a resistance value sufficiently larger than that of the Poly-Si resistor 27.
(It does not need to be doped with impurities). On the other hand, the lower half Poly-Si resistor 27 'in FIG.
Also has a ladder-like shape, and except for a portion having the longest distance as a resistor, the upper part of the ladder-like resistor has a Poly-Si doped with a p-type impurity.
The layer 31 is formed in an island shape via a SiO ₂ layer (not shown). The resistance value of this resistor is mainly p, which is the longest distance in the ladder step where the high resistance part 30 is provided.
In the ladder step portion having the Poly-Si layer 31 doped with the impurity of the type, it can be considered that the resistor is formed only in the portion having the shortest distance. (To be exact,
The ladder-shaped resistors are connected in parallel, and are calculated as the reciprocal of the sum of the reciprocals of the respective resistance values. ) Here, when the laser is irradiated so that the ladder portion where the high resistance portion 30 is provided is sufficiently overlapped with the high resistance portion 30 and the resistors 27 at both ends thereof, the ladder is formed on the resistors 27 and 30. Phosphorus is diffused into the high resistance portion 30 from the PSG film (not shown) formed, and the resistance value of the high resistance portion 30 is sufficiently reduced to be in a short circuit state. That is, by sequentially irradiating the laser from the high resistance portion 30 on the side where the distance of the resistor 27 is the longest, the resistance value between 12 and 12 'is reduced stepwise. In addition, P doped with p-type impurities
When the ladder step having the olly-Si layer 31 is irradiated with the laser so as to be sufficiently overlapped in the width direction of the resistor 27,
The p-type impurities diffuse and the resistance value of the laser irradiation portion increases. When the impurity concentration of the Poly-Si layer 31 is set to be in a balance with the impurity concentration of the resistor 27 after laser irradiation, an extremely high resistance value is obtained in the laser irradiation portion, and the laser irradiation portion is changed to an insulating layer. Can also be considered. That is, by irradiating the Poly-Si layer 31 doped with p-type impurities and the resistor 27 underneath the resistor 27 with a laser in order from the side with the shortest distance of the resistor 27, a gap between the electrodes 12 and 12 'is obtained. The resistance value of is gradually increased. From the above, by selecting the laser irradiation position, the resistance value between the electrodes 12 and 12 'can be arbitrarily increased / decreased. Next, FIG. 10 shows another embodiment of a resistor which can increase / decrease the resistance value according to the present invention. A Poly-Si resistor 32 doped with n-type impurities is formed between the Al electrodes 12 and 12 '. In the n-type Poly-Si resistor 32, the resistance value adjusting portion is rectangular, and a high resistance portion 33 having a constant width is formed in a direction perpendicular to the current flow path except for a part thereof. This high resistance portion 33 is a poly-Si resistor 3
Poly-Si (which may not be doped with impurities) has a resistance value sufficiently larger than 2. Further, at a position sufficiently distant from the high resistance portion 33, in parallel with the high resistance portion 33, the Poly-Si layer 34 in which the upper layer of the resistor 32 is doped with p-type impurities is formed in an island shape, and the SiO ₂ layer ( (Not shown in the drawing), but is partially removed. The resistance value of this resistor is mainly determined by the shape excluding the high resistance portion 33. Here, first, from the side where the resistor 32 remains, the high resistance portion 33 and the resistor 32 around it are sequentially overlapped with each other under certain conditions (for example, the resistor 32 is subjected to removal processing). The laser irradiation area is increased while irradiating the laser with a power density of 1/3 of the power density capable of producing SiO 2 on the resistor 32.
_Since phosphorus diffuses into the high resistance portion 33 from the PSG film (not shown) formed via the _two films and the high resistance portion has a low resistance, the resistance value between the Al electrodes 12 and 12 'is It will decrease. Further, P doped with p-type impurities
The resistor 32 is provided for the portion having the olly-Si layer 34.
From the side where the remains, and under the above conditions,
By increasing the laser irradiation area, p-type impurities diffuse into the resistor 32 and the resistance value of the laser irradiation portion increases, so that the resistance value between the Al electrodes 12 and 12 'increases. From the above, by selecting the laser irradiation position, the resistance value between the electrodes 12 and 12 'can be arbitrarily increased or decreased. Moreover, in the case of the resistor shown in FIG. 9, the resistance value changed stepwise, but in the case of the present embodiment, by making the movement pitch of the laser irradiation position sufficiently fine, almost continuously. The resistance value can be changed. In the embodiment shown in FIGS. 9 and 10, the resistor 2 is used.
7 and 32 show the case where n-type Poly-Si, the n-type impurity source is PSG, and the p-type impurity source is a p-type impurity-doped Poly-Si layer, the present invention is not limited to this. Not something. For an n-type Poly-Si resistor, a Si layer (Poly) doped with an n-type impurity as an n-type impurity source.
(Not limited to -Si), or a metal film that becomes an n-type impurity, or BSG as a p-type impurity source.
A film or a metal film that becomes a p-type impurity, and a poly-type doped with a p-type impurity as a resistor.
It is clear that the same effect can be obtained by using Si. Further, in this embodiment, the impurity source is formed in the upper layer of the resistor, but the present invention is not limited to this. For example, in the lower layer of the resistor (via the SiO ₂ film serving as a barrier).
It may be formed, and is particularly suitable when a metal film is used as an impurity source. In the present embodiment, the case of irradiating a laser using the optical system shown in FIG. 5 has been described.
The present invention is not limited to this, and the same effect can be obtained by irradiating a Gaussian focused spot with an optical system generally used for laser processing. As described above, according to the present invention, the resistance value of the resistor in the semiconductor integrated circuit can be arbitrarily increased / decreased without damaging the passivation film. There is an effect that a semiconductor integrated circuit having high performance and high reliability can be manufactured with high yield.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a conventional resistance value adjusting method. FIG. 2 is a diagram illustrating a conventional resistance value adjusting method. FIG. 3 is a diagram illustrating a conventional resistance value adjusting method. FIG. 4 is a diagram showing a structure of a resistor according to the present invention. FIG. 5 is an explanatory diagram of a laser optical system most suitable for adjusting the resistance value of the resistor according to the present invention. FIG. 6 is a diagram showing changes in the number of laser irradiation pulses and the resistance value. FIG. 7 is a diagram illustrating a laser irradiation method. FIG. 8 is a diagram showing changes in the number of laser irradiations and resistance values. FIG. 9 is a diagram showing another embodiment of the resistor of the present invention. FIG. 10 is a diagram showing another embodiment of the resistor of the present invention. [Description of Reference Signs] 1 ... Si substrate, 2 ... SiO ₂ film, 3, 11, 27, 32 ... Resistor, 5, 12 ... Electrode (pad), 13 ... SiO ₂ film, 14 ... N-type impurity doped Poly-Si, 15, 31 ... Poly-doped with p-type impurities
Si, 16, 17 ... Insulating film (passivation film), 30, 33 ... High resistance part.

Continued front page    (72) Inventor Takao Kawanabe               1450, Kamimizuhonmachi, Kodaira, Tokyo               Hitachi Musashi Factory (72) Inventor Morio Inoue               1450, Kamimizuhonmachi, Kodaira, Tokyo               Hitachi Musashi Factory                (56) References JP-A-60-9153 (JP, A)                 Japanese Patent Publication 5-12862 (JP, B2)

Claims (1)

(57) [Claims] 1. A film containing conductive impurities of the same conductivity type as the conductive impurities contained in the resistance wiring film at a higher concentration than the resistance wiring film, on the resistance wiring film containing conductive impurities connecting between the electrode pads; A semiconductor integrated circuit, wherein at least one of a film containing a conductive impurity having a conductivity type opposite to that of the conductive impurity in a concentration higher than that of the resistance wiring film is formed. 2. A film containing conductive impurities of the same conductivity type as the conductive impurities contained in the resistance wiring film at a higher concentration than the resistance wiring film, on the resistance wiring film containing conductive impurities connecting between the electrode pads; a conductive impurity opposite conductivity type conductive impurities a method of manufacturing a semiconductor integrated circuit formed at least one of the film containing a higher concentration than the resistance wiring layer, the semiconductor integrated circuit, the resistance wire The membrane has a structure in which multiple "ladder step" shaped portions are connected, and at least one of the ladder steps of at least one "ladder step" shaped portion is left with a high resistance part of all or part of the ladder steps. formed in the layer including the high-resistance portion between the impurity of the impurity of the same conductivity type which are doped to the resistor via the electrical insulating layer so as to overlap the resistor portion of both ends is formed, further reduced Also one of the other "Hashigodan" like
The shape part leaves at least one step of the ladder step part ,
A part or the whole of the ladder step is opposed to the impurity doped in the resistance wiring film through the electrically insulating layer.
The structure has a layer containing impurities of a conductivity type, by irradiating the ladder step where the high resistance portion is formed or the ladder step where the layer containing impurities of a different type is formed with laser light, A method of manufacturing a semiconductor integrated circuit, wherein a resistance value of a resistance wiring film can be arbitrarily increased or decreased.