JPS61273283A - Laser marking method for sos - Google Patents

Abstract

PURPOSE:To execute laser marking to Si without damaging and contaminating on Si surface of an IC forming surface by making an ultraviolet ray emitted from an excimer laser transmit through a sapphire from a sapphire surface side of an SOS, and irradiating it to the Si. CONSTITUTION:A silicon-on-sapphire (SOS) 9 is installed so that a sapphire 7 faces a condensing lens 5 side. An ultraviolet ray 2 emitted from an excimer laser 1 is bent by a bender 3, made to pass through a stencil 4, also condensed by the condensing lens 5, and irradiated to the surface of the sapphire 7 of the SOS 9. The ultraviolet ray 2 transmits through the sapphire 7, and an Si 8 is brought to marking. The Si whose thickness is about 1mum is transparent against a visible light, therefore, printing which has been brought to marking can be seen from both the sapphire 7 side and the Si 8 side, and a classification of a wafer can be executed. Since the surface of the sapphire 7 is a laser beam irradiating surface, there is no possibility that the Si surface bein an IC forming surface is damaged and contaminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for laser marking 5O8 (silicon on sapphire) used for substrates such as high frequency ICs.

[Prior art and its problems]

Si has conventionally been used as a substrate material for ICs, but recently SOS is expected to be used as a substrate for high frequency ICs. As shown in FIG. 2, the SOS is a wafer in which a sapphire 818 of about 1 μm is placed on a sapphire 7 of several hundred μm.

By the way, when using a board, there is a print mark for classification.
markings). Laser marking methods are used for such marking, but conventionally,
The laser marking method for Si wafers is carried out as shown in Figure 4 [Hatani Kogyo Co., Ltd., Catalog 05]
83013000 (0')]. According to this method, the ultraviolet light 2 emitted from the excimer laser 1 is transferred to the bender 3.
and pass it through a stencil 4 having a laser beam transmitting part.
Furthermore, the ultraviolet light 2 transmitted through the stencil 4 is collected by a condensing lens 5.
The light is focused and marked on the Si wafer 6.

Although there have been no reports of laser marking SOS, it is possible to mark the 5oSO3i surface by using the above-described laser marking method for Si wafers. However, in this case, since the Si surface becomes the laser beam irradiation surface, there is a very high risk that the Si surface will become dirty or scratched. Since the Si surface is the IC forming surface, it is a big problem that it gets dirty or scratched.

[Purpose of the invention]

The purpose of the present invention is to prevent the Si surface of SOS from becoming dirty.

An object of the present invention is to provide an SOS laser marking method that allows laser marking without causing scratches.

[Structure of the invention]

The present invention is an SO
In laser marking S, ultraviolet light emitted from an excimer laser is irradiated from the sapphire surface side of the SOS, and silicon is laser marked with the ultraviolet light that has passed through the sapphire.

[Effect]

Excimer laser is a high peak output pulsed ultraviolet laser, and as an excimer laser used in laser marking method, XeCf! Excimer laser (oscillation wavelength 308nm)
), KrF x, ximer laser (oscillation wavelength 249 nm)
, ArF x ximer laser (oscillation wavelength: 1931 m).

FIG. 3 shows the transmittance curve of sapphire in the ultraviolet region. As can be seen from this figure, the laser beam of the excimer laser described above passes through sapphire with a transmittance of nearly 100%. Therefore, even if the laser is irradiated from the sapphire surface of the SOS, it is possible to mark 81 through the sapphire.

In this way, when the SOS laser marking is performed from the sapphire surface, there is no risk of staining or scratching the S1 surface, which is the IC forming surface, so that laser marking can be performed without any problem.

〔Example〕

Next, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram for explaining one embodiment of the present invention, in which a laser marking device similar to that used for the conventional laser marking of a Si wafer in FIG. 4 is used.

According to this embodiment, after installing the 5O89 so that the sapphire 7 faces the condenser lens 5 side, the ultraviolet light 2 emitted from the excimer laser 1 is bent by the pengu 3, passed through the stencil 4, and then transmitted through the stencil. Ultraviolet light 2 is focused by a condensing lens 5 and irradiated onto the surface of 5039 sapphire 7. The ultraviolet light 2 passes through the sapphire 7 and marks Si8. Note that since Si with a thickness of ~1 μm is transparent to visible light, the marked print can be seen from both the sapphire 7 side and the Si 8 side, making it possible to classify Weno\.

According to this embodiment, since the surface of the sapphire 7 is the laser beam irradiation surface, the Si surface, which is the IC forming surface, may be scratched.
There is no fear of getting it dirty.

In the above example, a laser marking method using a stencil having a laser beam transmitting part was explained, but by sweeping ultraviolet light and irradiating the laser beam from the sapphire surface of the SOS,
Si may be marked.

〔Effect of the invention〕

As described above, according to the present invention, laser light is irradiated from the sapphire surface of SO3 to mark Si, so the SO3 laser does not scratch or stain the S1 surface, which is the IC forming surface. A marking method is obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining one embodiment of the present invention, Fig. 2 is a cross-sectional view of SOS, Fig. 3 is a diagram showing the transmission curve of sapphire in the ultraviolet region, and Fig. 4 is a diagram showing the transmission curve of conventional Si. FIG. 3 is a diagram for explaining a laser marking method. ■・・・Excimer laser 2・・・・・・Ultraviolet ray 3・・・Pengu 4・・・Stencil 5・・・Condensing lens 6・・・・・・Si wafer 7... Sapphire 8... Si 9... SOS Agent Patent attorney Yoshiyuki Iwasa Figure 1 Figure 2 511 & nm Figure 3 Figure 4

Claims (1)

[Claims] (1) SOS (silicon placed on top of sapphire)
A method for laser marking SOS, which is characterized by irradiating ultraviolet light emitted from an excimer laser from the sapphire surface side of the SOS, and marking silicon with the ultraviolet light that has passed through the sapphire. .