JPH0659623B2 - Wafer mechanochemical polishing method and apparatus - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method and an apparatus for polishing a wafer, and more particularly to S
The present invention relates to a wafer polishing method and apparatus for holding one side of a wafer such as i, GGG, GaAs and the like and polishing the other side, aiming to improve the flatness of a processed surface.

[Background of the Invention]

First, a conventional wafer polishing apparatus and a polishing method using the same will be described.

FIG. 1 is a schematic side view showing a conventional wafer polishing apparatus,
2 is a detailed side view of the holder shown in FIG. 1, and FIG. 3 is a partial sectional view showing another example of the holder.

In FIG. 1, reference numeral 5 is a rotary platen having a polishing cloth 4 adhered to the surface thereof, and the rotary platen 5 is rotationally driven around its rotary drive shaft 5a. Reference numeral 1 denotes a holder made of a corrosion-resistant material such as a stainless steel material or a ceramic material in which the wafer 2 is adhered (for example, four pieces are adhered) to the surface facing the polishing cloth 4. 7 is an abrasive.

1A is another example of the holder, and the holder 1A is one in which the wafer 2 is sucked by the vacuum means 6.

Using the polishing apparatus thus configured, the holder 1 (or 1A) is pressed against the polishing cloth 4 by a pressure support plate (not shown), and the polishing agent 7 is supplied to the wafer 2
When polished, the processed surface of the wafer 2 has a concave shape, resulting in poor flatness.

[Object of the Invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a method for polishing a wafer having an excellent flatness of a processed surface and a polishing apparatus used directly for this purpose.

[Outline of Invention]

The structure of the method for polishing a wafer according to the present invention is such that the polishing agent is supplied while pressing the wafer held by the holder onto the polishing cloth of the rotary platen that is driven to rotate by bonding the polishing cloth to the surface. In the mechanochemical polishing method of polishing the wafer by, by detecting the temperature of at least the central portion and the peripheral portion of the wafer during polishing, and compare the detected temperature with a preset temperature,
Based on the result of the comparison, the temperature of the holder is controlled so that the wafer has a predetermined temperature and a uniform temperature distribution.

Further, the temperature of the holder is controlled by a fluid flowing through a flow path formed inside the holder, and based on the detected result, the detected temperature of at least the central portion and the peripheral portion and the detection of each temperature. The difference in temperature is compared with a preset temperature and preset temperature difference, and the temperature and flow rate of the fluid are increased by increasing the flow rate when the difference in detected temperature is larger than the preset temperature difference. Is smaller than the set temperature difference, the flow rate is kept as it is, and when the detected temperature is higher than the set temperature, the temperature is lowered, and the detected temperature is lower than the set temperature and the difference between the detected temperatures is the set temperature. When the difference is larger than the difference, the temperature is kept as it is, and when the detected temperature is lower than the set temperature and the difference in the detected temperature is smaller than the set temperature difference, the temperature is raised. Ri is obtained by the wafer so that a uniform predetermined temperature and the temperature distribution.

Further, the structure of the wafer polishing apparatus according to the present invention comprises a holding means for holding a wafer, a rotary platen means having a polishing cloth adhered to the surface thereof, a rotary drive means for rotationally driving the rotary platen means, and a polisher. A polishing agent supply means, and the polishing cloth is supplied from the polishing agent supply means while pressing the wafer against the polishing cloth of the rotary platen means which is rotationally driven by the rotation drive means. In a mechanochemical polishing apparatus for polishing a wafer, the holding means embeds temperature detecting means for detecting the temperature of at least the central portion and the peripheral portion of the wafer, and the holding means is a fluid for adjusting the temperature of the wafer. Comparing the result detected by the fluid supply means connected to the flow passage means and the temperature detection means with a preset temperature Serial it from the fluid supply means those to and control means for controlling the temperature and flow rate of the fluid supplied to the passage means.

Further, the structure of the wafer polishing apparatus according to the present invention is such that a rotating platen having a polishing cloth adhered to its surface is rotated around its rotation drive shaft to hold the wafer on the surface facing the polishing cloth. In the wafer polishing apparatus for pressing the polishing cloth by the pressure supporting plate to polish the wafer while supplying the polishing agent, the temperature sensor for detecting the temperature distribution of the processed surface of the wafer in the holder,
A slip ring for extracting the temperature detected by the temperature sensor to the outside is attached, and a fluid supply hole for supplying water to the vicinity of the processed surface of the wafer is bored,
Control for comparing the detected temperature and the detected temperature difference taken out from the slip ring with the preset absolute temperature and the temperature difference, and calculating the temperature and flow rate of the supply water for making the temperature of the processing surface substantially uniform. An apparatus and a constant temperature water supply apparatus capable of supplying water having a temperature and a flow rate instructed by the control apparatus to the fluid supply hole are provided.

Example of Invention

Before starting the description of the embodiments, the basic matters according to the present invention will be described with reference to FIGS.

FIG. 4 is a cross-sectional view of an essential part showing a holder for measuring the temperature distribution of the processed surface of the wafer during polishing, and FIG. 5 shows the temperature of the processed surface of the wafer measured by the holder according to FIG. It is a processing time-temperature diagram.

The present inventors manufactured the holder 1B shown in FIG. 4 and measured the temperature distribution of the processed surface of the wafer 2 during polishing using the holder 1B.

In FIG. 4, 8 is a temperature sensor for detecting the temperature of the processed surface of the wafer 2 buried in the measurement holes formed at various positions in the radial direction of the holder 1B, and 9 is these temperature sensors. A slip ring for taking out the temperature detected by 8 to the outside, and 10 is a wiring connecting the slip ring 9 and each of the temperature sensors 8.

Further, a is a central portion of the wafer 2 and b and c are peripheral portions of the wafer 2.

The temperature change of the processed surface of the wafer 2 is as shown in FIG. 5, and it was found that the temperature of the central portion a was higher by about 1 ° C. than that of the peripheral portions b and c. This temperature distribution is due to the chemical action in the mechanochemical polishing of the wafer 2 (here, the mechanochemical polishing indicates a processing method of polishing with an abrasive having a combined mechanical action and chemical action in which fine abrasive grains are dispersed). It was found that the polishing efficiency of the central portion a having a high temperature is increased, the polishing amount of the central portion a of the wafer 2 is larger than that of the peripheral portions b and c, and the processed surface has a concave shape.

Therefore, in order to uniformly polish the wafer 2 and obtain a processed surface having excellent flatness, it is necessary to make the temperature distribution of the processed surface of the wafer 2 uniform.

Hereinafter, the present invention will be described with reference to examples.

FIG. 6 is a schematic side view showing an example of a polishing apparatus used for carrying out a method for polishing a wafer according to an embodiment of the present invention, and FIG. 7 is a diagram showing details of the holder shown in FIG. 8 is a sectional view taken along the line VIII-VIII in FIG.
In FIG. 6, the same reference numerals as those in FIG. 1 denote the same parts.

Explaining the outline of this polishing apparatus, 1C is equipped with a temperature sensor 8 for detecting the temperature distribution of the processed surface of the wafer 2 and a slip ring 9 for taking out the temperature detected by the temperature sensor 8 to the outside. The holder is provided with a fluid supply hole 11 for supplying the cooling water 16 to the vicinity of the processed surface of the wafer 2. Reference numeral 12 denotes the cooling water 16 for comparing the detected temperature and the detected temperature difference taken out from the slip ring 9 of the holder 1C with the preset absolute temperature and the temperature difference to make the temperature of the machined surface substantially uniform. This is a control device that calculates the supply temperature and flow rate of. Reference numeral 13 is a constant temperature water supply device having a built-in water storage tank capable of supplying the cooling water 16 at the temperature and flow rate commanded by the control device 12 to the fluid supply hole 11.

The holder 1C will be described in detail. The holder 1C includes a rotating portion 19 and a fixed portion 18, both of which are mechanical seals.
They are connected by means of 17, and are fixed to a base 15 by a fixing portion 18 via a pressure support plate 14. Four wafers 2 are adhered to the surface of the rotating part 19 facing the polishing cloth of the rotary platen 5, and the four wafers 2 are bonded to the central part a and the peripheral parts b and c of the wafer 2 to face the polishing cloth. A temperature sensor 8 for detecting the temperature of the processed surface is embedded. Also, the rotating unit 19
Has a fluid supply hole 11 formed concentrically with the wafer 2, and these fluid supply holes 11 communicate with each other through a radial flow path. Then, the cooling water 16 flows in the forward flow path 20.
Is supplied to the fluid supply hole 11 in the central portion of the wafer 2 and gradually flows to the peripheral side, and then the constant temperature water supply device 13 via the return flow path 21.
Return to.

The polishing operation of the wafer by the polishing apparatus thus configured will be described.

The wafer 2 is adhered to the holder 1C, which is set on the rotary platen 5, and the holder 1C is supported by the pressing support plate 14 while being pressed against the polishing cloth 4. Controller 12
Set the absolute temperature, temperature difference and polishing time in advance.

Here, when the polishing device is turned on, the rotary platen 5 is rotated in the direction of the arrow by the rotary drive shaft 5a, and the polishing cloth 4 is rotated.
Abrasive 7 is supplied upward. Cooling water 16 is supplied from the constant temperature water supply device 13 to the fluid supply hole 11 via the forward circuit 20 of the holder 1C, and returns to the constant temperature water supply device 13 via the return flow path 21 and circulates. The temperatures of the central portion a and the peripheral portions b and c of the wafer 2 are detected by the temperature sensor 8 and input to the control device 12 via the slip ring 9. In the control device 12, the detected temperature and the detected temperature difference are compared with the set absolute temperature and the temperature difference (intermittently, for example, every minute). Then, when the detected temperature difference is larger than the set temperature difference and the detected temperature is higher than the set absolute temperature, the temperature of the cooling water is lowered and the flow rate is increased from the current state. Is too large and the detected temperature is lower than the set absolute temperature, maintain the temperature of the cooling water and increase the flow rate from the current value.The detected temperature difference is within the set temperature difference and the detected temperature is higher than the set absolute temperature. If it is higher, lower the temperature of the cooling water and maintain the flow rate.If the detected temperature difference is within the set temperature difference and if the detected temperature is lower than the set absolute temperature, raise the temperature of the cooling water and maintain the flow rate. Is calculated,
This calculation result is instructed to the constant temperature water supply device 13. From this constant temperature water supply device 13, cooling water of the commanded temperature and flow rate is supplied.
16 is supplied to the fluid supply hole 11 of the holder 1C and the temperature distribution of the processed surface of the wafer 2 becomes uniform, so that the processed surface is uniformly polished. Then, after the lapse of the set time, the polishing apparatus is turned off, and the polishing of the wafer 2 is completed.

According to the embodiment described above, the wafer 2 under polishing
Since the surface temperature of the processed surface can be kept uniform, the polishing efficiency of mechanochemical polishing can be made uniform within the processed surface, and the flatness can be greatly improved.

In the present embodiment, the cooling water 16 was supplied from the start of the polishing apparatus, but in the initial stage of polishing, high temperature water (for example, from the constant temperature water supply apparatus 13 to the fluid supply hole 11 of the holder 1C) (for example, If high temperature water of 40 to 60 ° C.) is supplied, the surface temperature of the processed surface of the wafer 2 rises, and the polishing efficiency of mechanochemical polishing is improved about twice as compared with the case of supplying cooling water. There is.

〔The invention's effect〕

As described in detail above, according to the present invention, the temperature distribution in the wafer surface during polishing, which greatly affects the flatness of the wafer polishing surface, is measured during polishing to adjust the temperature of the wafer. By controlling the temperature and flow rate of the fluid, the temperature difference between the central portion and the peripheral portion of the wafer being polished can be adjusted to 1 ° C. or less, so that a wafer having a superior flatness of the processed surface can be obtained. It became so.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a conventional wafer polishing apparatus,
FIG. 2 is a detailed side view of the holder shown in FIG. 1, FIG. 3 is a partial cross-sectional view showing another example of the holder, and FIG. 4 is for measuring the temperature distribution of the processed surface of the wafer during polishing. FIG. 5 is a sectional view showing the main part of the holder of FIG. 5, FIG. 5 is a processing time-temperature diagram showing the temperature of the processed surface of the wafer measured by the holder of FIG. 4, and FIG. 6 is one embodiment of the present invention. FIG. 7 is a schematic side view showing an example of a polishing apparatus used for carrying out the method for polishing a wafer according to FIG. 7, FIG. 7 is a longitudinal sectional view of an essential part showing details of the holder in FIG. 6, and FIG. FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7. 1C ... Holder, 2 ... Wafer 4 ... Polishing cloth, 5 ... Rotating surface plate, 5a ... Rotation drive shaft, 7 ... Abrasive agent, 8 ... Temperature sensor, 9 ... Slip ring, 11 ... ... Fluid supply hole, 12 ... Control device, 13 ... Constant temperature water supply device, 14 ... Pressurizing support plate, 16 ... Cooling water, a ... Central part, b, c ... Peripheral part.

Claims (3)

[Claims] 1. A mechanism for polishing a wafer held by a holder by polishing the wafer by adhering a polishing cloth to the surface of the wafer and pressing the polishing cloth of a rotary platen which is rotationally driven to supply an abrasive. In the chemical polishing method, the temperature of at least the central portion and the peripheral portion of the wafer is detected during polishing, the detected temperature is compared with a preset temperature, and the temperature of the holder is based on the comparison result. Is controlled to maintain a predetermined temperature and temperature distribution of the wafer uniformly, and a mechanochemical polishing processing method for the wafer. 2. The temperature of the holder is controlled by a fluid flowing through a flow path formed inside the holder, and based on the detected result, the temperature detected in at least the central portion and the peripheral portion and The difference between the respective detected temperatures is compared with a preset temperature and a preset temperature difference, and the temperature and the flow rate of the fluid are increased by increasing the flow rate when the difference between the detected temperatures is larger than the preset temperature difference. When the temperature difference is smaller than the set temperature difference, the flow rate is kept as it is, when the detected temperature is higher than the set temperature, the temperature is lowered, and the detected temperature is lower than the set temperature and the detected temperature difference is If it is larger than the set temperature difference, the temperature is kept as it is, and if the detected temperature is lower than the set temperature and the difference in the detected temperature is smaller than the set temperature difference, the temperature is raised. And, the mechanochemical polishing method of processing the claims claim 1 wherein the wafer, characterized by maintaining the wafer uniform predetermined temperature and the temperature distribution. 3. A rotating means comprising a holding means for holding a wafer, a rotary platen means having a polishing cloth adhered to the surface thereof, a rotary drive means for rotationally driving the rotary platen means, and an abrasive supplying means. A mechanochemical polishing apparatus for polishing the wafer by supplying the polishing agent from the polishing agent supply means while pressing the wafer against the polishing cloth of the rotary platen means driven by the drive means while the holding means presses the wafer. In the holding means, the temperature detecting means for detecting the temperature of at least the central portion and the peripheral portion of the wafer is embedded, and the holding means has a fluid passage means for adjusting the temperature of the wafer, The fluid supply means connected to the flow path means and the result detected by the temperature detection means are compared with a preset temperature, and the fluid supply means is connected to the flow path means. Mechanochemical polishing processing apparatus of a wafer, characterized in that a control means for controlling the temperature and flow rate of the fluid supplied.