JP3488724B2 - Semiconductor wafer heating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer heating apparatus used for baking and heating a silicon wafer in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus, it is necessary to heat a semiconductor wafer such as silicon by using a heating device such as a heater in an exposure device, an etching device and the like. In this case, the purity of the heating device is higher than room temperature. Becomes important. This is because impurities are more likely to diffuse into the semiconductor wafer as the temperature rises, and therefore the material of the heating device for the semiconductor wafer is severely limited.

Generally, regarding the purity of the surface in contact with a semiconductor wafer, elements such as alkali metals, alkaline earth metals, and heavy metals that adversely affect the semiconductor element are used as impurities, and Si, Al, and C are excluded. , N, O as main components, and the purity is preferably 99.9% or more. Therefore, Fe (iron) type stainless steel material and Ni (nickel)
Heat-resistant alloys containing, etc. cannot be used.

Therefore, as a conventional semiconductor heating device,
A method of indirectly heating the lamp by light, or placing a semiconductor wafer on a low-purity heater via a high-purity aluminum plate and heating the semiconductor wafer is used.

[0005]

However, conventional indirect lamp heating by light is heating by radiation and is not an efficient heating method, so that heating at 300 ° C. or higher is difficult. Also, there should be no obstacles that block light rays between the lamp and the semiconductor wafer, and the design route was often restricted. Furthermore, when the temperature distribution occurs on the semiconductor wafer, it is impossible to control the temperature distribution to be narrowed.

Further, in the method of placing a semiconductor wafer on a low-purity heater via a high-purity aluminum plate and heating it, since the heating is performed via the aluminum plate, there is a time lag in heating or heat dissipation occurs. However, it was difficult to control the soaking. Further, due to the deformation of the aluminum plate due to heating, the contact pressure between the aluminum plate and the semiconductor wafer changes, and temperature unevenness and warp of the semiconductor wafer are likely to occur. Further, due to the difference in coefficient of thermal expansion between the aluminum plate and the semiconductor wafer, the aluminum plate and the semiconductor wafer slide with each other as the temperature rises, which causes the generation of particles. Further, these parts are often exposed to corrosive gases such as plasma and hydrofluoric acid, and aluminum plates are easily corroded.

As described above, conventionally, there is no suitable semiconductor wafer heating device.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention provides a semiconductor wafer heating apparatus comprising a single crystal sapphire plate-shaped body having a heating resistor on its back surface and a semiconductor wafer mounting surface formed on the front surface thereof. The mounting surface of the semiconductor wafer has a flatness of 1 μm or less, the single crystal sapphire plate is directly provided with a heating resistor, and the single crystal sapphire plate is provided so as to cover the heating resistor. It is characterized in that it is attached to a base plate or a pedestal made of alumina or single crystal sapphire, and a plurality of electrode lead-out portions for energizing the heating resistor are provided on the base plate or the pedestal. Furthermore, the present invention is characterized in that the single crystal sapphire plate-shaped body is attached to the base plate or the pedestal using an organic adhesive.

[0009]

[0010]

According to the present invention, the surface of the heater in contact with the semiconductor wafer is made of single crystal sapphire, and it is easy to obtain high purity single crystal sapphire of 99.99% or more. Even if the semiconductor wafer is directly contacted and heated, it does not contaminate the wafer at a high temperature.

Also, single crystal sapphire is from room temperature to 800
Since it has a high insulating property even at a high temperature of ℃, a heater having an extremely small leakage current can be obtained. For these reasons, it is possible to freely design the shape of the heating resistor of the heater and control the soaking.

Also, single crystal sapphire has a temperature of 100 to 100
Maintains its strength up to 0 ° C and Young's modulus is 4.7 x
It shows a high value of 10 ⁵ MPa and is stable against temperature changes so that warpage is unlikely to occur and the wafer can always be contacted uniformly. Further, single crystal sapphire is also excellent in chemical resistance and plasma resistance, and can be suitably used in etching devices, film forming devices and the like.

[0013]

EXAMPLES Examples of the present invention will be described below.

As shown in the perspective view of FIG. 1 and the sectional view of FIG. 2, the heater for heating a semiconductor wafer of the present invention comprises a plate-shaped body 1 made of single crystal sapphire and a heating resistor 2 on the back surface thereof.
The plate-shaped body 1 and the base plate 4 are arranged so as to cover the heating resistor 2.
It is made by joining.

Here, the joining of the plate 1 and the base plate 4 is
A bonding agent 3 as shown in FIG. 3 can be used, and as this bonding material 3, an organic adhesive, an inorganic adhesive, glass attachment, metallization, brazing, an active metal method, plating or the like can be used. Since the use temperature and the like are limited depending on the selection of the bonding agent 3, a bonding method suitable for the application may be used.

Further, the plate-shaped body 1 and the base plate 4 can be joined without using the joining agent 3. In this case, if the base plate 4 is made of single crystal sapphire or polycrystalline alumina ceramics, the joint surface of the plate body 1 and the base plate 4 is mirror-finished, and both are pressure-bonded at high temperature, the single crystal sapphires or the single crystal sapphire are bonded together. Direct fusion bonding between crystalline sapphire and polycrystalline alumina ceramics is possible.

Further, the base plate 4 is used by being fixed to a pedestal 5 formed of single crystal sapphire or polycrystalline alumina ceramics, but the pedestal 5 is not always necessary.

A plurality of electrode lead-out portions 4a for energizing the heating resistor 2 are formed in the base material 4, and a voltage is applied from the power supply 7 to the heating resistor 2 through these electrode lead-out portions 4a. As a result, the heating resistor 2 generates heat, and the mounting surface 1a is inserted through the plate-shaped body 1 made of single crystal sapphire.
The semiconductor wafer 6 placed on the can be heated.

The mounting surface 1a of the plate-shaped body 1 can be a highly accurate surface having a flatness of 1 μm or less, and therefore the semiconductor wafer 6 can be heated uniformly and uniformly. .

The material of the heating resistor 2 is as follows.
Tungsten (W), platinum (Pt), nickel (N
i), chromium (Cr), titanium nitride (TiN), and the like, and mixtures thereof. Any material can be used as long as it is a heating resistor, and these heating resistors 2 can be formed into a predetermined pattern by a metallizing method or the like. Good.

Next, another embodiment of the present invention will be described.

In the heater for heating a semiconductor shown in FIG. 4, the plate-shaped body 1 made of single crystal sapphire and the base material 4 made of polycrystalline alumina ceramics are directly joined by high temperature fusion, and the base plate 4 is preliminarily formed into a pattern shape. The paste is poured from the electrode extraction portion 4a into the formed gap 8 and baked,
The heating resistor 2 is formed by applying electroless plating. This semiconductor heating heater is easy to form the heating resistor 2 and is excellent in mass productivity.

Further, as still another embodiment, as shown in FIG. 5, the plate-like body 1 and the base plate 4 made of single crystal sapphire are prepared by metallization by the Mo--Mn method or by using an active metal made of Ti alloy. It is also possible to bond them and use this metallized layer or active metal layer as the heating resistor 2.

Further, in the present invention, the heating resistor 2 does not necessarily have to be embedded between the plate-shaped body 1 made of single crystal sapphire and the base plate 4. That is, as shown in FIG. 6 as another embodiment, the mounting surface 1a of the plate-shaped body 1 made of single crystal sapphire.
It is also possible to form the heat generating resistor 2 on the surface opposite to the above and to fix the insulating pedestal 5 thereunder via the bonding agent 9. In this case, as the bonding agent 9, an adhesive, glass, silicone resin, or the like is used. Further, as the pedestal 5, a polycrystalline ceramic material of alumina or single crystal sapphire is used.

[0025]

Further, in the above-mentioned embodiments, only the plate-shaped body 1 made of single crystal sapphire is directly provided with the heating resistor 2, but the present invention is not limited to this, and for example, a heater having a heating resistor is plate-shaped. It goes without saying that it may be provided on the back side of the body 1.

Example 1 As an example of the present invention, a heater shown in FIG. As the plate-shaped body 1 made of single crystal sapphire, EFG (Edge) is used.
-Defined Film-fed Growth)
Using the method, a 6-inch-wide single crystal sapphire was pulled up to prepare a plate-like body 1 having a diameter of 6 inches and a thickness of 0.2 mm. The physical properties of the single crystal sapphire produced at this time are shown in Table 1, and the purity is shown in Table 2.

Similarly, a single crystal sapphire base plate 4 having a diameter of 6 inches and a thickness of 3 mm was produced by the EFG method. The electrode lead-out portion 4a is opened in the base plate 4, a groove 8 is formed with a depth of 0.1 mm so as to have a desired heating resistor shape, and then the bonding surface between the plate-shaped body 1 and the base plate 4 is mirror-polished. After fusing, they were fused at 1800 ° C.

Then, a tungsten (W) paste was injected into the inside from the electrode extraction portion 4a and baked in a reducing atmosphere to form the heating resistor 2. The internal resistance 2 may be formed by electroless plating or the like.

[0030]

[Table 1]

[0031]

[Table 2]

Example 2 As an example of the present invention, a heater shown in FIG. 5 was prototyped. A single crystal sapphire plate 1 and a single crystal sapphire base plate 4 similar to those in Example 1 were formed, and metallized joining was performed by the Mo—Mn method. In this case, Mo-Mn
Titanium nitride (TiN) or the like is mixed with the metallization to adjust the resistance value, and the metallized layer itself becomes the heating resistor 2.

Example 3 As the heater shown in FIG. 5, a plate-like body 1 made of single crystal sapphire and a base plate 4 made of polycrystalline alumina ceramics were formed as in Example 1, and metallized joining was carried out by the Mo-Mn method. went. Also in this case, the Mo—Mn metallized layer itself whose resistance is adjusted by another compound such as titanium nitride (TiN) becomes the heating resistor 2.

[0034]

Reference Example As a reference example, the heater shown in FIG. 6 was manufactured as a prototype. Example 1
A plate-like body 1 made of single crystal sapphire similar to the above is electrolessly plated as a heating resistor 2 on the back surface, and then the plate-like body 1 is placed on a pedestal 5 of high-purity aluminum whose surface is anodized (aluminum oxide film). 2 with epoxy resin
A low temperature type heater having a temperature of 00 ° C. or lower was manufactured.

Experimental Example A silicon wafer heating test was conducted using the heaters of Examples 1 to 3 and the reference example. As the conditions, the degree of vacuum was set to 10 ⁻³ Torr, heating was performed up to 200 ° C. and 500 ° C., and the temperature variation at that time was evaluated. As a control experiment, lamp heating and indirect heating using an aluminum plate were evaluated.

Regarding the purity of the surface in contact with the wafer, the purity of the alkali metal, alkaline earth metal, heavy metal, etc.
An element that adversely affects the semiconductor element was used as an impurity, and Si, Al, C, N, and O, excluding these elements, were used as the main components, and the purity was evaluated based on whether they were 99.9% or more.

The temperature variation was defined as the difference between the maximum and minimum values of the temperature on a heated 6-inch wafer measured radially at 17 points using a thermocouple. The temperature variation must be at least 20 ° C or less, and preferably 10 ° C or less.

[0039]

[Table 3]

As can be seen from Table 3, in the comparative example, the temperature variation was as large as 20 ° C. or more, while in the case of using the heater of the present invention made of single crystal sapphire, all of them were of high purity and sufficiently high. It was found that excellent soaking characteristics were obtained, and it could withstand use in semiconductor manufacturing equipment.

Further, in the heater of the present invention, when the current flowing between the heating resistor 2 and the semiconductor wafer 6 was measured, this leakage current had a current value of several tens to several μA and was at a problematic level. It was confirmed that there was not.

[0042]

As described above, according to the present invention, there is provided a semiconductor wafer heating apparatus comprising a single crystal sapphire plate-shaped body having a heating resistor on the back surface and a semiconductor wafer mounting surface formed on the front surface thereof. The mounting surface of the semiconductor wafer has a flatness of 1
and a base plate made of alumina or single crystal sapphire so that the single crystal sapphire plate is provided with a heating resistor directly on the single crystal sapphire plate and covers the heating resistor. By being attached to a pedestal, the base plate or the pedestal is provided with a plurality of electrode lead-out portions for energizing the heating resistor,
It is possible to obtain a heater having a feature that sufficient soaking required when heating a semiconductor wafer is obtained and that the semiconductor wafer is less likely to be contaminated.

Since the leakage current is extremely small,
It is preferably used as a heater used in an exposure device, an etching device, and the like. In addition, the mechanical properties and sliding characteristics are particularly excellent, and the coefficient of thermal expansion of the heater surface can be made small, so the heater that has been processed with high accuracy can maintain the initial accuracy in a wide temperature range, and the high accuracy of the processing pattern. It is possible to provide a heater for heating a semiconductor wafer, which has various features such as being made possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing a semiconductor heating heater of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is an enlarged view of part A in FIG.

FIG. 4 is a vertical cross-sectional view showing another embodiment of the semiconductor heating heater of the present invention.

FIG. 5 is a vertical cross-sectional view showing another embodiment of the semiconductor heating heater of the present invention.

FIG. 6 is a vertical sectional view showing another embodiment of the semiconductor heating heater of the present invention.

[Explanation of symbols]

1 ... plate-shaped body 1a ... Mounting surface 2 ... Heating resistor 3 ... Bonding agent 4 ... Base plate 4a ... Electrode extraction part 5 ... Pedestal 6 ... Semiconductor wafer 7 ... power supply 8 ... Groove 9 ... Bonding agent

─────────────────────────────────────────────────── --- Continued from the front page (56) References JP-A-4-181725 (JP, A) JP-A-59-39348 (JP, A) JP-A-5-93275 (JP, A) JP-A-58- 150288 (JP, A) JP 58-199047 (JP, A) JP 59-99715 (JP, A) JP 1-289089 (JP, A) JP 3-226986 (JP, A) JP-A-3-236186 (JP, A) JP-A-6-291175 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/31 H01L 21/324 H01L 21/68 C23C 14/50

Claims (2)

(57) [Claims] 1. A semiconductor wafer heating apparatus comprising a single crystal sapphire plate-shaped body having a heating resistor on the back surface and a semiconductor wafer mounting surface formed on the front surface, wherein the mounting surface of the semiconductor wafer is a flat surface. 1 μm or less, the single crystal sapphire plate is directly provided with a heating resistor, and the single crystal sapphire plate is made of alumina or single crystal sapphire so as to cover the heating resistor. A semiconductor wafer heating apparatus mounted on a base plate or a pedestal, wherein the base plate or the pedestal is provided with a plurality of electrode lead-out portions for energizing the heating resistors. 2. The single crystal sapphire plate-shaped body is the base.
It is attached to the board or pedestal using an organic adhesive.
The semiconductor wafer heating according to claim 1, wherein
apparatus.