WO2012119280A1

WO2012119280A1 - Guard electrode device for ultra-shallow junction deep-ultraviolet laser annealing apparatus

Info

Publication number: WO2012119280A1
Application number: PCT/CN2011/001192
Authority: WO
Inventors: 周卫; 严利人; 刘朋; 窦维治
Original assignee: 清华大学
Priority date: 2011-03-09
Filing date: 2011-07-21
Publication date: 2012-09-13
Also published as: CN102169816A; CN102169816B

Abstract

Provided is a guard electrode apparatus for a deep-ultraviolet laser annealing apparatus used for the manufacture of semiconductor components. In the present invention, a guard electrode (4) is provided above a processed wafer (7); said guard electrode is positioned above a wafer chuck (6) and the processed wafer, and is parallel to the surface of the processed wafer; the center of the electrode is provided with a small aperture (5), allowing for the passage of a deep-ultraviolet laser; the guard electrode faces the laser beam and remains static; the laser annealing apparatus emits a pulse laser beam (2) by means of a deep-ultraviolet laser device (1); the laser beam passes through an optical path (3) for beam expansion, beam homogenization, and edge processing, is then projected onto the wafer chuck, said chuck being capable of X-Y-plane, two-dimensional precision positioning and movement, and finally performs laser annealing on the processed wafer located on the chuck. The wafer chuck is capable providing two-dimensional uniform or step movement. The wafer chuck is grounded, the guard electrode faces the wafer chuck, and the wafer has negative potential. This allows for control of the external photoelectric effect produced by deep ultraviolet laser irradiation, and prevents damage to components caused by electrons escaping from the wafer.

Description

Shield electrode device in ultra-shallow junction deep ultraviolet laser annealing equipment

The present invention is in the field of semiconductor manufacturing equipment, and more particularly to a shield electrode assembly for a deep ultraviolet laser annealing apparatus used in semiconductor manufacturing.

Background technique

When the feature size of a semiconductor device represented by a CMOS integrated circuit and a large-capacity memory is continuously reduced, and the process node enters 32 nm and 22 nm, it is required to fabricate a device structure having a heavily doped, ultra-shallow MOS device source-drain extension region. That is, the requirements for making Ultra-Shallow Junction (US J) are proposed in the process. In order to meet the requirements of ultra-shallow PN junctions for 32nm nanometers and below generations on 300 awake wafers, in addition to the new technical measures to be used in impurity doping technology i, in the annealing process of impurity activation, it is necessary to Light-based rapid thermal annealing (RTA) methods make changes. The currently accepted ultra-shallow junction annealing process is a laser annealing technique with a deep ultraviolet wavelength.

The benefits of using deep UV laser annealing technology are:

1) The deep ultraviolet laser has a short wavelength and has a shallow depth of direct action on the material, which only affects the ultra-shallow surface area;

2) Since the annealing laser is pulsed, the laser pulse is on the order of tens of nanoseconds, and the annealing is performed. U is on the wafer scanning or field stepping mode. Therefore, the total annealing time is short and the annealing step can be 3⁄4 impurity. The re-diffusion control is at a level close to zero diffusion;

3) Obtaining impurity doping solubility of super-solubility, reducing the electrical attachment of the ultra-shallow PN junction source and drain extension region, and improving the ohmic contact of the source-drain electrodes.

The ultra-shallow, steep PN junction fabricated by deep-UV laser annealing technology can meet the needs of 32nm and below process node integrated circuit manufacturing.

It should be pointed out that the laser annealing equipment or laser annealing technology currently on the market can only process PN junctions with junction depths of several hundred nm or more. Using the traditional annealing technique, it is completely unsuitable for the 32nm technology node from the mechanism and mode of annealing. For the production of ultra-shallow knots. Therefore, the deep ultraviolet laser annealing referred to in the present invention specifically refers to a laser annealing technique for ultra-shallow junction fabrication. At present, laser annealing equipment and 13⁄4 process technology for ultra-shallow junctions are still in the experimental research stage.

For ultra-shallow junction laser annealing, since the single-pulse energy of currently available lasers is low, and the entire wafer cannot be simultaneously annealed, only the line scan or field stepping can be used to achieve annealing of the entire substrate wafer. At the same time, the substrate material needs to be heated, which not only reduces the influence of thermal stress generated on the substrate by the use of 'strength laser annealing, but also reduces the energy density threshold of laser annealing to the order of 350 mJ/cm ² .

Under the irradiation of deep ultraviolet laser, a phenomenon called external photoelectric effect occurs, that is, electrons on the substrate material are escaping from the surface of the processed circle due to the irradiation of the short-wavelength deep ultraviolet laser, which destroys The original electrical neutrality of the material makes it possible for the device to be defective during the manufacturing process, which affects the yield and reliability of the device.

The external photoelectric effect refers to the process by which a substance absorbs photon energy to emit free electrons. The resulting electron is called photoelectron, which is related to the wavelength of the incident light, that is, to the frequency of the light. No |nj's substance has a red limit frequency v. , only when the frequency V of the incident light is higher than the red limit frequency V of the irradiated substance. When, ie v > v. At this time, the electrons in the matter can absorb the photon energy and escape from the substance table. Otherwise, even if the light intensity is large, the external photoelectric effect of the electron escape does not occur; in addition, the initial energy of the photoelectron is related to the frequency of the incident light, and is incident. The intensity of light is irrelevant.

Based on the above principle, in order to reduce such defects generated during device fabrication, the present invention provides a solution for applying an electrode having a negative potential to a wafer above the surface of the wafer to be processed, specifically By placing a shield electrode with a negative potential above the processed wafer, electrons are prevented from escaping from the wafer, ensuring that the device is not damaged during the laser annealing process.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a shield electrode device for use in a deep ultraviolet laser annealing apparatus for a semiconductor device fabrication process, characterized in that a shield electrode is placed over a wafer to be processed, and the shield electrode is located on the carrier wafer and Above the processed wafer, parallel to the surface of the processed wafer, The center of the electrode has a small hole for the deep ultraviolet laser to pass through, the electrode is stationary with respect to the laser beam, and the distance from the processed wafer is in the range of l~10 mm, the electrode is opposite to the carrier sheet and is added: I The wafer is at a negative potential, and the applied reverse bias voltage is 5 to 100 V; the external photoelectric effect due to electron escaping generated by deep ultraviolet laser annealing can be effectively suppressed, and the device is not damaged by the deep ultraviolet laser annealing.

The deep ultraviolet laser has a wavelength of 193ηπ! ~ 350nm, pulsed laser beam single pulse energy M is 200mJ~1. 5J, pulse width is 10~: L000ns, repetition frequency 10~: L000Hz.

The carrier stage is a f-stage with heating device capable of two-dimensional precise positioning and movement, and the platform can perform uniform or stepwise movement in the XY direction, thereby achieving uniformity of the laser beam to the entire piece. Annealing, the temperature at which the wafer is heated by the wafer is in the range of 300 to 550 °C.

The small hole of the shielding electrode, when the deep ultraviolet laser annealing device uses a small circular spot, and the line is drawn to anneal the processed wafer, the small hole is a circular hole slightly larger than the laser spot; The laser annealing equipment adopts a wire harness, and when the surface of the processed wafer is fired by surface scanning, the small hole is a rectangular slit slightly larger than the laser spot; when the deep ultraviolet laser annealing device is processed by the field stepping method When the wafer is annealed, the small hole is a rectangular hole having a size slightly larger than that of the laser.

The processed wafer refers to a wafer containing a semiconductor material in a semiconductor wafer or other form, such as S0I, SGOI, G0I (here, S refers to Si material, G refers to Ge material, 0 is ^乂on). The prefix, I is the English Insulator prefix).

The invention has the beneficial effects of adding a shielding electrode above the processed wafer, the electrode is stationary with respect to the laser beam, and is negatively pressed with respect to the carrier sheet and the wafer, which can effectively prevent the deep ultraviolet laser from being applied to the wafer. The external photoelectric effect produced by the illumination causes damage to the device.

DRAWINGS

Figure 1 is a schematic diagram of a shield electrode device in a deep ultraviolet laser annealing apparatus. In the figure, 1- is: a deep ultraviolet pulse laser; a 2-laser beam, 3- is used to expand, converge, and rim the laser beam. Processed light path, 4-shielded electrode; 5-hole on the shield electrode, 6- can be XY dimension Precise positioning and movement, and can heat the wafer carrier, 7-processed wafer.

Figure 2 is a schematic view of a small hole in the shield electrode, wherein

a, when using line scan, the hole on the shield electrode is circular, 4-shield electrode, 5. 1-screen fc i i丄 hole on the pole, 6-bearing table, 7-processed wafer.

b, when the laser beam is a wire bundle, when the surface scanning mode is used, the small hole on the shielding electrode is a rectangular slit, 4-shield electrode, 5. 2-shaped rectangular slit on the shielding electrode, 6-bearing film table, 7 - Being processed into a circle J-.

c, when the laser beam is a rectangle, when the field stepping method is used for annealing, the small hole on the shielding electrode is a rectangular hole, the 4-shield electrode, 5. the rectangular hole on the 3-shield electrode, the 6-bearing film table, 7- is crowned with discs.

detailed description

The present invention provides a shielding electrode device for a deep ultraviolet laser annealing apparatus for a semiconductor device fabrication process. The present invention will be further described below in conjunction with specific embodiments.

Figure 1 is a schematic view of a shield electrode assembly in a deep ultraviolet laser annealing apparatus. A shield electrode 4 is placed over the wafer to be added: 1 and the shield electrode is located above the carrier sheet 6 and the processed circle Ί 7 Parallel to the surface of the processed wafer, there is a small hole in the center of the shield electrode 4. The laser beam 2 generated by the deep-outside laser 1 can be transmitted, and the shield electrode 4 is stationary with respect to the laser beam 2, in the laser 1 and shielded. Between the electrodes 4, an optical path 3 for expanding, averaging, and arranging the laser beam is provided, and the distance between the shield electrode 4 and the processed wafer 7 is in the range of 1 to 10 Torr. The shielding electrode ^1 has a negative potential with respect to the carrier sheet 6 and the processed wafer 7, and the applied reverse bias voltage is 5 to 100 V; the external photoelectric effect due to electron escape generated by deep ultraviolet laser annealing can be effectively suppressed. , to ensure that the device will not be damaged by deep ultraviolet laser annealing.

Embodiment 1

When using line scan, the small hole on the shield electrode is circular (as shown in Figure 2a). The structure and application of the shield electrode device:

1 直径1, 0 ram,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, The laser beam 2 can be transmitted; 2) the shielding electrode 4 is parallel to the wafer 7, and the distance from the wafer is 4 mm;

3) The shielding electrode 4 has a negative potential with respect to the carrier stage 6 and the wafer 7, and the voltage is 5-25V;

4) The carrier sheet 6 drives the wafer 7 to move relative to the laser beam 2, and it performs a reciprocating motion at a constant speed along the Y-axis, and a stepping motion of 0. 2 ram/step along the X-axis.

Embodiment 2

In the surface scanning mode, the laser beam is a wire bundle, and the small hole in the shielding electrode is a rectangular slit (as shown in FIG. 2b). The structure and application of the shielding electrode device include:

2, The size of the rectangular slit is 2. 0x11. 0 Sa, can make the laser Beam 2 through;

2) The shielding electrode 4 is parallel to the wafer 7, and the distance from the wafer is 6;

3) The shielding electrode 4 has a negative potential with respect to the carrier stage 6 and the wafer 7, and the voltage is 5-30V;

4) The carrier table 6 drives the wafer 7 to move relative to the laser beam 2, and performs a reciprocating motion along the Y-axis, and a stepping motion of 8. Omm/step along the X-axis.

Embodiment 3

When the field stepping method is used for annealing, the laser beam is a rectangular beam, and the small hole on the shielding electrode is a rectangular hole (as shown in Fig. 2c), and the shielding electrode device, the structure and application manner thereof include:

The laser beam 2 can be transmitted through the laser beam 2 through a rectangular hole 5. 3, a rectangular hole 5. 3 size is 9. 0x13. 0mm, the laser beam 2 can be transmitted through the laser beam 2 ;

2) The shielding electrode 4 is parallel to the wafer 7, and the distance from the wafer is 8 mm;

3) The shielding electrode 4 has a negative potential with respect to the carrier stage 6 and the wafer 7, and the voltage is 10-60V;

4) The carrier table 6 drives the wafer 7 to move relative to the laser beam 2, and performs stepwise movement along the X-axis and the Y-axis, and the step spacing along the X-axis is 7. Wstep stepping motion, along the Y-axis The stepping motion of the step spacing is 11.9 mm/step.

Claims

Claim

A shielding electrode device in a deep ultraviolet laser annealing apparatus, characterized in that a shielding electrode is disposed above a wafer to be added, the shielding electrode is located above the carrier wafer and the processed wafer, The surface of the processed wafer is parallel, and a small hole in the center of the electrode can transmit the deep ultraviolet laser. The electrode is stationary with respect to the laser beam, and the distance from the processed wafer is in the range of 1~: LOmm, and the electrode is opposite to the bearing. The wafer and the processed wafer are at a negative potential, and the applied reverse bias is 5~100V; the external photoelectric effect due to electron escape generated by deep ultraviolet laser annealing can be effectively suppressed, and the device is not prevented from adopting deep ultraviolet rays. Laser annealing and damage.

The singularity of the pulsed laser beam is 200 mJ~1. 5J, the pulsed laser beam has a wavelength of 193 nm to 350 nm, and the single pulse energy of the pulsed laser beam is 200 mJ~1. The pulse width is 10~: L000ns, and the repetition frequency is 10~: L000Hz.

3. The shield electrode assembly of the deep ultraviolet laser annealing apparatus according to claim 1, wherein the carrier stage is a platform with a heating device capable of two-dimensional precise positioning and movement, the platform can Uniform or stepping motion is performed along the χ-γ direction to achieve uniform annealing of the entire wafer by the laser beam. The temperature at which the wafer is heated by the wafer is 300~550 °C.

4. The shield electrode assembly of the deep ultraviolet laser annealing apparatus according to claim 1, wherein the small hole of the shielding electrode is processed by a deep circular laser spot annealing device using a small circular spot. When the wafer is annealed, the small hole is a hole slightly larger than the laser spot; when the deep ultraviolet laser annealing device uses a wire harness to anneal the processed wafer by surface scanning, the small hole is a small size A rectangular slit larger than the laser spot; when the deep ultraviolet laser annealing apparatus anneals the processed wafer by field stepping, the small hole is a rectangular hole slightly larger than the laser spot.

A shield electrode assembly in a deep ultraviolet laser annealing apparatus according to claim 1, wherein said processed wafer is a S0I, SG0I or G0I wafer containing a semiconductor material.