JPH0831644B2 - Semiconductor manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a semiconductor manufacturing apparatus using laser light.

(Conventional Technology) Conventionally, energy beam irradiation technology capable of locally supplying high-density power in a short time has been researched and developed as an alternative method for semiconductor manufacturing equipment using an electric furnace, etc. It is developing to the research of the element aiming at the original integrated circuit. This energy beam irradiation technology includes a method using a laser beam and a method using an electron beam. Especially, the laser beam is used for processing various semiconductors because it has little damage to the semiconductor wafer and thermal distortion. There is.

As processing using this laser beam, irradiation damage due to ion implantation, activation of implanted impurities, and recrystallization of polycrystalline silicon are performed to produce single crystal silicon.
There is an annealing treatment device such as SOI (Silicon on Insulator) technology, which is disclosed in Japanese Patent Publication No. 62-27532 and Japanese Patent Laid-Open No. 61-289617. Further, there is a CVD processing apparatus for selectively forming a film on a semiconductor substrate using a laser beam, which is disclosed in JP-A-60-5.
No. 3017 etc.

(Problems to be Solved by the Invention) However, the conventional laser optical system such as the above device is
Since only aberration correction for monochromatic light was performed and correction for chromatic aberration over the entire wavelength range of laser light including multiple wavelengths such as Ar laser was not performed, differences in focal length for each wavelength occur, and ideal The laser light output was not used effectively and the loss of the laser light output was large.

Moreover, the laser optical system has a large laser light output because it uses a normal optical lens such as BK7 or F2, which is the most commonly used and most stable optical glass produced among optical glasses. When the optical path length is changed due to the thermal expansion of the lens due to the absorption of the laser light and the like, and the laser output is changed, the focal length is changed and the beam spot diameter is affected.

Therefore, due to the problems of aberration correction and change in optical path length, when performing processing using a laser beam, the beam spot diameter becomes large, so the laser light loss becomes large, and the desired laser beam output and power density at the surface to be processed are increased. If you increase the laser light output after adjusting the beam spot diameter, etc., the beam spot diameter will change and you will not be able to create a laser beam of the desired output with the desired size, and the laser beam will also become unstable. There was a problem of becoming.

The present invention has been made in consideration of the above points, enables correction of aberrations of laser light having a plurality of wavelengths, prevents optical path length change due to absorption of laser light, and ensures processing of semiconductors and the like by laser light. It is intended to provide a semiconductor manufacturing apparatus which can be stably performed.

[Structure of Invention]

(Means for Solving the Problems) The present invention is characterized in that the lens of the optical system uses two or more kinds of athermal lenses having different Abbe numbers.

(Operation) By constructing the lens of the optical system of the laser light with two or more kinds of materials having different Abbe numbers, it becomes possible to correct the aberration of the laser light having a plurality of wavelengths, for example, Ar laser, for example, the chromatic aberration. . Then, by using athermal glass as the material of this lens, it is possible to prevent thermal change of the lens due to absorption of laser light, and prevent occurrence of optical path length change due to change of laser light output.
This makes it possible to achieve desired optical performance.

(Embodiment) An embodiment in which the device of the present invention is applied to a laser annealing device for synthesizing and annealing two laser beams in a semiconductor manufacturing process will be described below with reference to the drawings.

An airtight chamber (1) made of Al that can be opened / closed by an opening / closing mechanism (not shown) is provided, and a semiconductor wafer (2) is held in the chamber (1) by pressing an edge of a substrate to be processed, for example, a semiconductor wafer (2). The semiconductor wafer (2) and the installation table (3) that holds the wafer so that the surface to be processed is facing down.
Multiple IRs with reflector (4) preheated to about 0 ° C
A lamp (infrared ray lamp) (5) is provided.

Further, below the semiconductor wafer (2) in the chamber (1), a window (6) made of a material that transmits laser light, for example, quartz glass is provided.

Two laser oscillators (7a, 7b), for example, 18 WAr ion lasers are provided so as to output a large output laser beam. A blocking unit (8a, 8b) capable of blocking the laser beam with a mirror, for example, a galvano scanner as a mirror rotation shutter is provided on each optical path of the output laser beam, and the mirror of the blocking unit is reflected. A cooling unit (9a, 9b) that absorbs laser light and cools with water cooling, forced air cooling or natural air cooling, for example, a black alumite treated Al heat sink is provided. Then, the laser beam that has passed through without being blocked by the blocking unit has a lens having an Abbe number so that the beam diameter at the time of processing can be converted and the beam diameter suitable for annealing processing can be narrowed down to the minimum, for example. The beam expander (10a, 10b) on the optical path is designed to expand the beam diameter by about 3 times with the beam expander (10a, 10b) using a lens showing two or more types of athermal properties different from each other. It is installed in.

From there, the total reflection type mirror (11a) and the polarizing prism (1
2) For example, a prism whose material is BK7A is provided.

Further, in order to adjust the beam profile and the like of the combined laser light, for example, two reflective optical attenuators (13a, 13b) capable of switching between 100% reflection and 1% reflection are set. Further, total reflection type mirrors (11b to 11f) are installed so that laser light can be transmitted to the lower part of the chamber (1).

A scanning unit (14) is provided so that the laser light sent to the lower part of the chamber (1) can be scanned on the semiconductor wafer (2) through the window (6). In the scanning unit (14),
An X-direction scanning mechanism (15), for example, a galvano-scanner which is a mirror rotation type scanning mechanism, is provided on a Y-direction scanning mechanism (16), for example, a uniaxial precision stage using a ball screw capable of high precision and minute feed. There is. And X-direction scanning mechanism (15)
The θ lens (17) that uses a lens that has two or more types of athermal properties with different Abbe numbers so that the scanning speed is constant in the center and periphery of the lens when scanning the laser beam scanned by It is provided on the Y-direction scanning mechanism (16).

The operation of the laser annealing apparatus having the above configuration is controlled and set by a control unit (not shown).

Next, a method of annealing the semiconductor wafer (2) by the above-described laser annealing device will be described.

The chamber (1) is opened by an opening / closing mechanism (not shown),
A hand arm semiconductor wafer (2) (not shown) is loaded into the chamber (1). Here, the semiconductor wafer (2) is
For example, center alignment and orientation flat alignment are performed in advance by detecting the edge of the wafer (2) at three or more points with a photodiode or the like and calculating it. And the wafer (2)
With the surface to be treated facing downward into the chamber (1),
Wafer (2) edge 5m on the installation table (3) in the chamber (1)
Hold about m and hold downward on the installation table (3).
At this time, if the semiconductor wafer (2) is preheated, damage to the wafer (2) due to thermal expansion can be prevented. Then, the chamber (1) is closed by an opening / closing mechanism (not shown).

Then, the semiconductor wafer (2) is heated by the reflection plate (4) and the IR lamp (5) to about 500 ° C., and then annealed by laser light. The uniform heating by the IR lamp (5) can prevent thermal strain and the like generated by local heat generation of the laser light. In addition, when the chamber (1) is purged with N ₂ gas during the annealing treatment, the temperature uniformity is further improved.

At this time, the two laser oscillators (7a, 7b) have already been stabilized in a high output state, and the laser light is reflected by the reflecting mirror (20) of the cutoff section (8) as shown in FIG. (9) For example, the heat of the laser light absorbed by the heat sink is cooled by natural cooling. When the laser light is annealed, the reflecting mirror (20) is rotated so as to be parallel to the laser light, and the laser light is emitted from the hole (21). This rotating mechanism is a galvano scanner which is a mirror rotating shutter,
Since it is a high-speed shutter of about 10 msec for rotating an angle of about 20 ° C., it does not adversely affect the annealing process on the semiconductor wafer (2). Further, as shown in FIG. 3, if an emergency cutoff mirror (22) is provided so that the laser light is cut off when the power is cut off, the accident due to the laser light is prevented even in the case of a power failure. be able to.
By providing the cutoff section (8) and the cooling section (9), the output of the laser oscillator (7a, 7b) is kept at a high output and the conversion of 0% and 100% of the laser output is ensured at high speed. It is possible to prevent the adverse effects of heat on the surroundings, and it is possible to turn on and off the high-power laser at low cost.

Then, the laser light that has passed through the blocking section (8a, 8b) for annealing treatment is converted into a beam expander (10a, 10b).
The beam diameter is once expanded to about 3 times. this is,
This is performed in order to narrow down the beam on the semiconductor wafer (2) to obtain a beam diameter suitable for the annealing process, which enables the wafer (2) to be annealed at a higher temperature, for example, 1000 ° C. or higher. This beam expander (10a, 10b) is made of, for example, material FK01 as shown in FIG.
With negative lens (25), material ATF4 with positive lens (26), material ATF4 with negative lens (27), material FK01 with positive lens (2
8). This FK01 is a crown glass system and has a refractive index n _d = 1.49700 indicating the degree of refraction of an object and an Abbe number indicating the degree of dispersion. Coefficient of linear expansion α = 127 × 10 ^-7 , temperature coefficient of length factor dn / dT = −5.
4 × 10 ⁻⁶ , optical path bending temperature coefficient ds / dT = 0.91 × 10 ⁻⁶ . Where the optical path length temperature coefficient ds / dT is And the temperature coefficient of refractive index is derived from the Lorentz-Lorenz equation. ATF4 is a flint glass system, and has a refractive index n _d = 1.65376, an Abbe number v _d = 44.7, a linear expansion coefficient α = 117 × 10 ⁻⁷ , and a temperature coefficient dn / dT = −6.5 × 1.
0 ^-6, the optical path length temperature coefficient ^{ds / dT = 1.15 × 10 -6} . And athermal glass is the temperature coefficient of refractive index dn / dT <0
Therefore, the optical path length temperature coefficient ds / dT is a glass material with almost 0,
In an optical system that changes with temperature, the optical path length does not change with temperature, and the focal length does not change. Therefore,
The above FK01 and ATF4 are athermal glasses exhibiting this athermal property. By the way, BK7, which is the most used optical glass, has ds / dT = 6.62 × 10 ^-6 and F2 has ds / dT = 8.7.
It is 9 × 10 ^-6 . Further, since it is composed of two or more kinds of lenses (25 to 28) having different Abbe numbers, it is possible to correct chromatic aberration in the entire wavelength range of 457.4 to 514.5 nm of laser light having a plurality of wavelengths, for example, Ar laser. That is, by using positive and negative lenses (25 to 28) of athermal glass whose optical path length change due to a change in laser light output is almost 0, aberrations of an optical system are corrected by combining materials with different Abbe numbers. Laser beam output loss due to beam spot change and focal length change due to output change can be prevented, a stable desired laser beam for processing can be realized, and annealing of the semiconductor wafer (2) by laser light can be surely stabilized. Can be done by

Next, the two laser beams are reflected by a mirror (11a) and a polarizing prism (1
Create a desired beam profile by combining in 2),
The laser light is sent to the scanning section (14) using mirrors (11b to 11f). At this time, when the beam profile or the like is adjusted, the laser light output is attenuated by using the optical attenuators (13a, 13b). The mechanism of the optical attenuator (13a, 13b) is, as shown in FIG. 5, a plurality of mirrors having different reflectances, for example, a 100% reflecting mirror (30) that reflects 100% of laser light and 1% of 99% after reflecting it. A 1% reflecting mirror (31) that transmits and absorbs, for example, a linear guide (3
2) and the parallel movement mechanism that uses the air cylinder (33) to change the parallel movement to achieve 100% laser output.
And decays to 1%. Further, this switching may be performed by rotational movement. And in this embodiment, by using two optical attenuators (13a, 13b), 100%, 1%, 0.01
% Laser output attenuation is possible. As a result, the desired attenuation rate required for each adjustment is realized. Also, 1%
Since the reflector (31) transmits and absorbs 99% of the laser light,
A heat sink (not shown) for cooling is provided on the back surface to prevent thermal influence on the surroundings. And this 100% reflector (3
Reflective optical attenuator (13) using 0) and 1% reflector (31)
By using a, 13b), it is possible to prevent interference of laser light, optical path bending, diffusion of laser light, disturbance of wavefront, etc., which occur due to a transmission type optical attenuation mechanism or the like. Further, in the case of performing light attenuation in two or more steps as in the present embodiment, a transmission type light attenuation must make a parallel plane plate that is precise and parallel and allows laser light to pass therethrough.
It is difficult to manufacture and adjust this parallel flat plate,
For example, an optical path correction plate was required to correct the optical path, but the reflection type solves the above problems, and a highly accurate optical attenuation mechanism can be easily realized.

Then, the adjusted laser light such as the beam profile and the optical axis is sent to the scanning unit (14) using the mirrors (11b to 11f). Here, the laser light has a desired constant speed by an X-direction scanning mechanism (15), for example, a galvano scanner and a θ lens (17), and passes through a window (6) onto the semiconductor wafer (2) in X-direction.
Similarly, the Y-direction scanning mechanism (16), for example, 1
The axial precision stage scans the semiconductor wafer (2) in the Y direction by desired scanning such as continuous scanning or step scanning.
The laser beam narrowed down by the θ lens (17) has a beam diameter of about 60 μm to 300 μm on the semiconductor wafer (2), and the temperature of the surface to be processed of the semiconductor wafer (2) becomes 1000 ° C. or higher, for example. This heat causes the wafer (2) to be annealed, and the X direction scanning mechanism (15) and the Y direction scanning mechanism (16) scan the desired portion or the entire surface of the wafer (2) to perform the annealing process. finish.

Here, the θ lens (17) for condensing the laser light on the semiconductor wafer (2) is made of, for example, a material as shown in FIG.
ATF4 positive lens (40), material FK01 negative lens (4
1), material ATF4 positive lens (42), material ATF4 negative lens (43), material ATF4 negative lens (44), material FK01 positive lens (45), material ATF4 negative lens ( 46), material
FK01 consists of a positive lens (47). Like the beam expanders (10a, 10b), this θ lens (17) is also a lens (40 to 47) that exhibits an athermal property in which the change in optical path length due to the change in laser light output is almost zero, and is made of materials with different Abbe numbers. Are combined.

Next, after blocking the laser light by the blocking sections (8a, 8b), the chamber (1) is opened by an opening / closing mechanism (not shown), and the semiconductor wafer (2) is carried out of the chamber (1) by a hand arm (not shown). , Processing is completed.

The blocking unit (8a, 8b) in the above embodiment has been described using the galvano scanner as the mirror rotary shutter, but it is sufficient if the optical path can be blocked by the mirror, and the rotary cylinder or the rotary solenoid may be equipped with the mirror. Needless to say, the mirror may be moved linearly at a high speed to block the optical path, and an AO modulator or an EO modulator may be used.

Further, the cooling unit (9a, 9b) of the above-described embodiment is described using the air-cooling black heat-treated alumite heat sink made of Al, but if it can cool by absorbing the laser light reflected from the blocking unit (8a, 8b). Any method may be used, such as a water cooling method using cooling water or forced air cooling using a fan, and is not limited to the above embodiment.

In the above embodiment, the beam expander (10a,
The beam diameter was once expanded in 10b) and narrowed down by the θ lens (17), but it is sufficient if the desired beam diameter and beam output can be obtained on the semiconductor wafer (2), and the laser oscillator (7a, 7b)
It is also possible to use the laser light emitted from the laser as it is and narrow it down onto the wafer (2) using a lens.

Further, in the above-mentioned embodiment, the description has been made by setting the parallel movement switching type optical attenuators (13a, 13b) of 100% reflection and 1% reflection in two places, but the reflectance, the switching method and the set number are the same as in the above embodiment. It goes without saying that it is not limited.

Then, in the scanning unit (14) of the above-mentioned embodiment, the X-direction scanning mechanism (15) and the Y-direction scanning mechanism (16) are explained using the galvano scanner and the one-axis precision stage, but the scanning which can realize the desired processing is performed. Any method may be used, either a raster scan method or a vector scan method, an XY stage may be used, a polygon mirror and a uniaxial stage may be used in combination, and two galvano scanners may be used. However, the present invention is not limited to the above embodiment.

In the above-described embodiment, the laser annealing apparatus that combines the two laser beams and performs the annealing process has been described, but any semiconductor manufacturing apparatus that processes the substrate to be processed using the laser beam may be used. It is needless to say that the laser beam to be used may be one or plural, and the treatment may be a CVD treatment or a mask repair treatment, and is not limited to the above embodiment.

Further, in the above-described embodiment, the lenses (40 to 47) forming the θ lens (17) of the optical system and the beam expander (10a,
The materials of the lenses (25 to 28) that compose 10b) are FK01 and ATF4.
As explained above, it is a glass that exhibits an athermal property in which the change in optical path length due to temperature change is almost zero, and it is sufficient if it is made of two or more materials with different Abbe numbers.
It may be used as a lens forming a sin θ lens or an ordinary lens, and is not limited to the above embodiment.

As described above, according to this embodiment, the semiconductor wafer (2) is preheated by the IR lamp (5) in the airtight chamber (1) and annealed by using laser light through the window (6). The beam expander (10a, 10b) of the optical system that guides the laser light and the lenses (25 to 28, 40 to 47) forming the θ lens (17) are connected to two or more types of athermal with different Abbe numbers. By using a lens exhibiting properties, it is possible to correct aberrations, prevent changes in optical path length, and obtain a desired stable laser beam during processing.

〔The invention's effect〕

As described above, according to the present invention, aberration correction of laser light having a plurality of wavelengths is realized by using, as the lens of the optical system, two or more kinds of athermal lenses having different Abbe numbers. Prevents loss of laser light output,
It is possible to prevent the change of the beam spot diameter due to the change of the optical path length caused by the thermal expansion of the lens and surely realize the processing of the semiconductor or the like by the laser light under desired stable conditions.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment in which a semiconductor manufacturing apparatus of the present invention is applied to an annealing treatment, FIG. 2 is a cross-sectional view for explaining a cutoff portion and a cooling portion of FIG. 1, and FIG. 3 is FIG. FIG. 4 is a longitudinal sectional view of FIG. 4, FIG. 4 is a configuration diagram of the beam expander of FIG. 1, FIG. 5 is a view for explaining the optical attenuator of FIG. 1, and FIG. 6 is θ of FIG.
FIG. 7 is a flow chart showing the annealing process of FIG. 1 in a simple manner. In the figure, 1 ... Chamber, 2 ... Semiconductor wafer 5 ... IR lamp, 6 ... Window 10a, 10b ... Beam expander 14 ... Scanning unit, 17 ... θ lens 25-28, 40-47 ... …lens

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirohiro Kumagai 1-226 Nishi Shinjuku, Shinjuku-ku, Tokyo Tokyo Electron Ltd. (72) Inventor Shimao Yoneyama 1-26 Nishishinjuku, Shinjuku-ku, Tokyo No. 2 inside Tokyo Electron Limited (72) Inventor Masao Shinno 3-4-14 Nihonbashihonmachi, Chuo-ku, Tokyo Inside Kowa Co., Ltd.

Claims (8)

[Claims] 1. A semiconductor manufacturing apparatus for irradiating a surface to be processed of a substrate to be processed with a laser beam guided by an optical system for processing, wherein the lens of the optical system has two or more types of athermal properties different in Abbe number. A semiconductor manufacturing apparatus characterized by using a lens showing 2. The semiconductor manufacturing apparatus according to claim 1, wherein the laser light is an Ar laser. 3. The semiconductor manufacturing apparatus according to claim 1, wherein the lens is a lens for condensing the laser light and a lens for enlarging the laser light. 4. The lens for condensing laser light is a lens that forms a θ lens whose scanning speed is constant at the center and periphery of the lens when scanning the laser light. The semiconductor manufacturing apparatus described. 5. The semiconductor manufacturing apparatus according to claim 3, wherein the lens for expanding the laser beam is a lens constituting a beam expander for converting the beam diameter. 6. The semiconductor manufacturing apparatus according to claim 1, wherein the lens exhibiting athermal property is constituted by a combination of a positive lens and a negative lens. 7. The semiconductor manufacturing apparatus according to claim 1, wherein the treatment is an annealing treatment. 8. The semiconductor manufacturing apparatus according to claim 1, wherein the substrate to be processed is a semiconductor wafer.