JPS63136545A - Laser-trimming device - Google Patents

Abstract

PURPOSE:To melt a fuse positively by simultaneously irradiating the same position in one part of a circuit with two kinds of laser beams having different wavelengths and imparting a melting function. CONSTITUTION:A YAG;Nd laser 104 and a YAG;Nd laser 114 are used in order to acquire two kinds of laser beams having a 1.064mum wavelength and a 0.532mum wavelength. The wavelength of laser beams output from the YAG;Nd laser 104 are converted into 0.532mum from 1.064mum by an SHG 105, the laser beams are condensed by an optical system 106, and the direction of the condensed laser beams is changed so as to be directed to a section just under a mirror 107 by the mirror 107 and the laser beams are projected to a fuse to be trimmed for a wafer 103. Laser beams oscillated from the laser 104 and the laser 114 are controlled by a control circuit 108 in order to simultaneously reach the wafer 103.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to internal fuses, wiring,
This invention relates to a laser trimming device for trimming resistors and the like.

[Conventional technology]

In recent years, in the production of semiconductor integrated circuits, circuits with redundant bits have been devised in order to increase the yield of semiconductor integrated circuit devices and produce them at lower costs. This is a circuit H11 with a larger number of pits than the desired number of memory bits.
This is a method of making a redundant bit in advance, and when the original bit is defective, a fuse prepared in advance is blown to make use of this redundant bit.

FIG. 4 is a membrane diagram of an example of a conventional laser trimming device.

A wafer 403 that requires trimming is placed on a single wafer 402 placed on a stage 401 of the laser trimming HfZ. A laser beam 405 with a wave Lc of 1.08 μm outputted from a YAG; Fuse to trim
incident on . The chip position within the wafer is determined by moving a stage 401 that moves in the X-Y directions.

Unlike the device of this example, a wavelength conversion element SHG is arranged inside the YAG laser 404, between the YAG laser 404 and the optical system 406, or inside the optical system 406, and the wavelength is changed from 1.064 μm to 0.532! There is also an apparatus that converts the shim into a shim and performs trimming using a laser beam having a wavelength of 0.532 μm.

In either case, polycrystalline silicon, polycide, silicide, A1, or the like is used as the fuse.

[Learning points while trying to solve the invention]

In the above-mentioned conventional laser trimming device that performs trimming using a laser beam with a wavelength of 1.064 μm, because the wavelength is long, the energy absorption coefficient of the fuse material for the wavelength of 1.064 μm is small, and it is difficult to cut the fuse. In order to do this, it is necessary to increase the energy of the laser beam to the fuse. Normally, when the laser energy is increased with a YAG laser, the variation in energy between pulses also becomes wide (becomes large), and although some fuses were definitely cut during trimming, other fuses destroyed even the base of the FuSe, causing accumulation. The circuit device itself may be destroyed.For this reason, the output of the YAG laser cannot be increased very much, which is a drawback.

On the other hand, in conventional Hl, which performs trimming using a laser beam with a wavelength of 0.532 μm, the wavelength is 0.5'3
Since the energy absorption coefficient of the fuse material at 2 μm is high, lower laser energy is required to cut the fuse than in the case of a wavelength of 1.064 μm. However, when FuSe is cut, there is usually an integrated circuit device on the FuSe.
A protective film is encased in the tube, and it is difficult to accurately control the thickness of this protective film, which is 0.1 μm (there is a difference in the thickness of the protective film).FuS When e is irradiated with laser light, if there is a film thickness error of about 0.1 μm due to reflection and interference of the laser light from the fuse material and protective film, the energy that can be absorbed by the fuse part will change greatly. The shorter the wavelength of the laser beam, the greater the effect; when trimming with a laser beam with a wavelength of 532 μm, some fuses were completely cut, but other fuses were not completely cut and only partially melted. There is a problem that the cut portions may be connected, and the integrated circuit device that should be repaired cannot be repaired.

The conventional single wavelength 1.064μm or 0.5μm mentioned above
In contrast to laser trimming (He) in which trimming is performed using a laser beam with a wavelength of 32 μm, the present invention uses two laser beams with different wavelengths, for example, a wavelength of 1.064 μm.
Simultaneously irradiates the fuse with a laser beam having a wavelength of 0.532 μm and a wavelength of 0.532 μm, effectively adding energy to the fuse, and not being affected by variations in the thickness of the integrated circuit device protective film on the fuse. It has the original content of being able to cut the fuse reliably.

[Means for solving the problem] The laser trimming device of the present invention performs laser trimming HH for cutting a part of a predetermined circuit with a laser beam, for example, at a wavelength of 1.064 μm and a wavelength of 0.532 μm.
Grooves are formed by simultaneously irradiating two types of laser beams emitting different wavelengths of μm to the same position on a part of the circuit and cutting the circuit.

〔Example〕

Next, embodiments of the present invention will be described using the drawings.

FIG. 1 is a schematic diagram for explaining the present invention in detail.

A stage 101 movable in two directions of X-Y is installed on a seismic stand 100. A wafer 102 for placing a wafer 103 that requires trimming is placed on a stage 101, and an optical f system 110 for wafer alignment is installed. Mirror 127. A television monitor camera 109 is installed. Wavelength 1.064μm and wavelength 0.5
In order to obtain a 32 μm two-plate laser beam, YAG:N
d laser 104 and YAG;? , Jd laser 114 are used. YAG; Nd laser 104
The wavelength of the laser beam output from the 5HG105 is converted from 1.064 μm to 0.532 μm,
The optical system 106 focuses the focused laser beam, and the mirror 107 changes the direction of the focused laser beam so that it goes directly below, and the wafer 1
03 enters the fuse to be trimmed. Also, Y
The laser beam output from the AG:Nd laser 114 is focused by an optical system 116, and the direction of the focused laser beam is changed by a mirror 117 so that it goes directly below, and then the IC/
The signal is input to the fuse 1103 to be trimmed. Mirror 117 is selected to be suitable for transmitting 0.532 μm wavelength laser light, and mirror 127 is selected to transmit 0.532 μm wavelength laser light.
An appropriate material is selected to transmit laser light with wavelengths of /1 μm and 0.532 μm. The laser beams emitted from the laser 104 and the laser 1111 should reach the wafer 103 at the same time (they are controlled by a control circuit 108).

Figure 2 shows PS as a protective film on polycrystalline silicon fuse.
The absorption rate of polycrystalline silicon for laser light when looking at the G film is shown in relation to the psGIU thickness.
Curve a is curve i when the laser beam wavelength is 0.532 μm.
b is a case where the laser beam wavelength is 1.084 μm. For example, when the PSG film thickness changes to 0.1 am, it is 1.06
It can be seen that the change in absorbance is suppressed smaller in the case of the 4 tt m wavelength than in the case of the 0.532 μm wavelength.

The energy absorption coefficient of polycrystalline silicon for 1.0 G 4 μm wavelength laser light and 0.532 μm wavelength laser light is 0.532 μm wave absorption coefficient, which is larger for 0.532 μm wavelength laser light than for 1.064 μm wavelength laser light, and the output is same[
When these laser beams are irradiated to the fuse part at once, the 0.532 μm wavelength light is more efficient for the fuse (
It is easily absorbed and the fuse is cut off.

Therefore, the laser trimming device of the present invention is different from the conventional device which performs trimming using a single wavelength light.
Force l on e<-1.064μ for film thickness variation
m laser beam is not affected by it, and 0.532μ
Since the m laser beam efficiently adds energy to the Fuse, the Fuse can be reliably cut. Here, the design of the laser, SHG, and laser optical system is not limited to this example.In short, it is sufficient to obtain two types of laser beams of 1.064 μm and 0.532 μm, and the mirror The presence or absence of this does not affect the essence of this embodiment. Also, 1.
The intensity of the 0.064 μm and 0.532 μm laser beams is Fu
The se material, the protective film on the fuse, etc. are appropriately selected.

FIG. 3 is a schematic diagram for explaining Example 2 of the present invention. A stage 301 movable in two X-Y directions is installed on a seismic stand 300. A wafer 302 for cutting a wafer 303 that requires trimming is installed on a stage 301, and an optical system 309 for wafer alignment is installed. E-Chief 30 and TV monitor camera 308 are installed. YAG: Nd laser 3
The wavelength of the laser beam 310 emitted from the laser beam 310 is converted from 1.064 am to 0°532 μm by the SHG 305. However, the laser beam with a wavelength of 1.064 μm is not 100% converted to 0.532 μm, and the laser beam 311 after passing through SHG 305 is a laser beam with a wavelength of 1.064 μm and a laser beam with a wavelength of 0.532 μm. It's mixed. These laser beams 311
is focused by an optical system 306, and the focused laser light is incident on the fuse of the wafer 303 to be trimmed. The optical system 306 is designed to be able to focus laser beams with wavelengths of 1.064 μm and 0.532 μm. In this example, laser beams of two different wavelengths can be obtained from one laser and irradiated to the fuse on the wafer at the same time, so energy can be effectively added to the fuse and the fuse can be
There is an advantage that the fuse can be reliably cut without being affected by variations in the thickness of the upper integrated circuit device protective film. Here, 5HG305 includes a laser 304 and an optical system 30.
It may be located not only between G but also within the laser 304 or the optical system 306. Also, 1.064 um
An appropriate ratio of the intensity of the laser beams of 0.532 μm and 0.532 μm is selected depending on the FusC material, the protective film on the fuse, etc.

〔Effect of the invention〕

As explained above, the present invention is applicable to 1.064 μm and 0.06 μm.
Fuse two laser beams of 532μm wavelength at the same time
By irradiating with This has the effect of increasing the yield in manufacturing circuit devices and providing them at low prices.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the first embodiment of the present invention, and FIG. 2 is an integrated circuit device protection device on polycrystalline silicon fuse.
A diagram showing the relationship between PSG film thickness and absorption rate when PSG is deposited. Figure 3 is a schematic diagram showing the second embodiment of the present invention. Figure 4 is a diagram showing conventional laser trimming. It is a schematic diagram of an example of a device. +00...Earthquake prevention stand, 300...Earthquake prevention stand, 4 old...
stage. 101... stage, 301... stage. 402...One wafer, 102...One wafer. 302...One wafer, 403...Wafer. 103...Wafer, 303...Wafer. ↓04...YAG; Nd laser. 104, 114...YAG: Nd laser. 304...YAG; Nd laser. ↓05・°°laser beam J105...S HG,
305...SHG. 406...Laser optical system. 106, 116... Laser optical system. 306... Laser optical system, ↓07... Mirror. 107, 117. 127... Mira
-, 307... Mira -. 108...Control circuit. 308...TV monitor camera. 109... Katamera for TV monitor. 309... Alignment optical system. 110... Alignment optical system. 310, 311...Laser light. Potato / Zubetsu Pu Junya Figure 3

Claims (2)

[Claims] (1) In a laser trimming device that cuts a part of a predetermined circuit with laser light, the function of cutting the part of the circuit by simultaneously irradiating two types of laser light with different wavelengths to the same position A laser trimming device characterized by having: (2) The wavelength of each of the two types of laser light is 1.064 μm
and 0.532 μm, the laser trimming device according to claim 1.