CN1495538A - Alignment method of array optical probe scanning integrated circuit photoetching system and its equipment - Google Patents

Abstract

The present invention relates to an aligning method in array type optical probe scanning integrated circuit photoetching system and its equipment. It includes the following steps: firstly, defining key point according to circuit diagram, coding difference characteristics of circuit diagram and etch-writing them on the silicon wafer, setting a pair of calibration graphs, making said calibration graph be positioned in circuit diagram place, and the calibration graph is formed from calibration subgraphs. According to the key point etch-writing calibration subgraph on the silicon wafer, when the etching is reached to graph key point, fetching calibration subgraph coordinate and comparing said coordinate with recorded calibration subgraph coordinate. The equipment includes the components of base sent, working table, servomotor, calibration optical head and optical probe array, etc.

Description

Alignment methods in the array type optical probe scanning IC photoetching system and device thereof

The application is that denomination of invention is that " alignment methods in the array type optical probe scanning IC photoetching system and device thereof ", application number are dividing an application of 01123501.2 application for a patent for invention.

Technical field the invention belongs to fine engineering and makes field, the aligning when being used for array type optical probe scanning IC photoetching system figure alignment.

Photoetching method is mainly adopted in the manufacturing of background technology large scale integrated circuit in modern age, on silicon chip, be coated with the last layer photo anti-corrosion agent material, utilization optics or electron exposure are delivered to circuitous pattern on the resist, and then by series of process such as development, etchings, finally obtain chip.At present, the live width of large scale integrated circuit has reached 0.18 μ m, and alignment precision is 0.03 μ m.

According to Rayleigh equation R=K * λ/NA, resolution R depends on the ratio of wavelength and numerical aperture.The traditional optical method is subjected to the restriction of principle and optical device, and resolution is difficult to can't satisfy the requirement of current large scale integrated circuit less than 0.1 μ m.Photoetching methods such as the X-ray that RECENT DEVELOPMENTS is got up, electron beam and the particle beams, electron beam and particle beams method can be made 0.1 μ m, but equipment is huge, and can only singly restraint scanning and inscribe, production efficiency is low.X smooth lithography also can be made the following live width of 0.1 μ m in theory, but has the mask manufacturing issue, fails to enter practicality.In order to improve inscription efficient, a plurality of light probes are formed array, inscribe a plurality of figures simultaneously.The alignment device of conventional lithography method adopts an alignment so, can't compensate inscribing error; Each circuitous pattern is aimed at respectively, and efficient is lower.

Summary of the invention the objective of the invention is to design a kind of alignment device, and technology such as that this device utilizes is optically read, servo driving can quick and precisely be located etching system, and in the alignment process, circuitous pattern is carried out proofreading and correct in real time synchronously.

Alignment methods in the array type optical probe scanning IC photoetching system of the present invention's design may further comprise the steps:

(1) according to treat on the silicon chip alignment be N capable * the precision height of the circuitous pattern of M row rectangular array, determine A key point of figure.

(2) distinguishing characteristics of circuitous pattern is encoded, and this coding is scribed on the silicon chip.

(3) top margin of the rectangular array that is made of circuitous pattern on above-mentioned silicon chip and base midpoint are provided with a pair of alignment pattern, make alignment pattern be positioned at the circuitous pattern place, and alignment pattern is made up of A the calibration spirte identical with above-mentioned key point number.

(4) the graphics critical point of determining according to the above-mentioned first step 1 is inscribed a calibration spirte correspondingly, and is write down this calibration spirte position coordinates on silicon chip.

(5) before the alignment, determine the coordinate parameters of this silicon chip according to the distinguishing characteristics of circuitous pattern.When alignment proceeds to graphics critical point, read calibration spirte coordinate, and the coordinate of the calibration spirte of this coordinate and above-mentioned record is compared, when two coordinates conform to, the continuation alignment; When two coordinates were not inconsistent, error in judgement was if temperature error then adopts homogenizing to handle, if stochastic error then continues alignment in calibration spirte position, and upgrades coordinate data.

(6) in alignment process repeatedly, the repeated using said process is until the inscription of finishing the entire circuit figure.

The alignment device that is used for array type optical probe scanning IC photoetching system of the present invention's design, this device comprises pedestal, worktable, silicon chip to be processed, light probe array, collimation optical head and reading device thereof.Worktable is placed on the pedestal, by the elaborate servo motor-driven, move along X, Y direction, silicon chip to be processed is fixed on the worktable by sucker, collimation optical head and light probe array are positioned at the silicon chip top, a pair of collimation optical head is positioned in the middle of the light probe array, along the Y-axis symmetry, and the rectangular arrangement of light probe array.The collimation optical headband has reading device, and this device comprises light source, diverging lens, polarization spectroscope, quarter-wave plate, condenser lens, photodetector.Light source reads signal by diverging lens, forms directional light, and this directional light is by polarization spectroscope, quarter-wave plate, condenser lens, at alignment pattern place flat focus, reflected light passes through condenser lens, quarter-wave plate and polarization spectroscope, and lens shine on the photodetector.

Characteristics of the present invention are:

1, inscribe for the first time before the circuitous pattern setting base, silicon chip information, circuitous pattern information are recorded on the silicon chip in the prealignment groove.

2, alignment pattern occupies a pair of circuitous pattern position, inscribes synchronously with circuitous pattern.Comprise manyly in the alignment pattern, be used for the positional information of writing circuit figure key point the calibration spirte.

3, during alignment,, the circuitous pattern coordinate is carried out proofreading and correct in real time synchronously and error compensation according to respectively calibrating spirte information in the alignment pattern.

4, in alignment process repeatedly, the absolute coordinates of circuitous pattern key point remains unchanged.

5, the collimation optical head is selected blue laser for use, for guaranteeing not destroy the calibration spirte in the calibration process, writes with high power, and weak power (Writing power 1/50th arrives one of percentage) reads.

Adopt the present invention to aim at, can once aim at all circuitous patterns, saved the aligning time, improved aligning efficient.And, in the alignment process, adopt multiple spot to proofread and correct, can in time compensate the error that causes by reasons such as temperature,, improve alignment precision the real-time synchronous correction of circuitous pattern, guarantee the quality of circuitous pattern, can effectively solve yield rate problem on the low side in the lithography industry.

Description of drawings

Fig. 1 for the present invention design array type optical probe scanning IC photoetching system in the alignment device structural drawing.

Fig. 2 is the vertical view of Fig. 1.

Fig. 3 is a silicon chip to be processed.

Fig. 4 is an alignment pattern enlarged drawing on the silicon chip.

Fig. 5 collimation optical reading device.

Fig. 6 calibrates extremely figure under four-quadrant photo detector of spirte.

Among Fig. 1-Fig. 6,1-pedestal, 2-worktable, 3-silicon chip, 4-collimation optical head, 5-light probe array, 6-elaborate servo motor, a 7-collimation optical reading device, 8-setting base coded message band, 9-alignment pattern, 10-circuitous pattern, 11-calibrates spirte, 51-light source, 52-diverging lens, the 53-polarization spectroscope, 54-quarter-wave plate, 55-condenser lens, the 56-condenser lens, the 57-photodetector, 61-calibrates spirte.

Embodiment

As shown in Figure 1, the alignment device that is used for array type optical probe scanning IC photoetching system of the present invention design comprises pedestal 1,2 of work, light probe array 5, collimation optical 4 and reading device 7 thereof.Worktable 2 is placed on the pedestal 1, drive by elaborate servo motor 6, move along X, Y direction, silicon chip 3 to be processed is fixed on the worktable 2 by sucker, collimation optical 4 and light probe array 5 are positioned at the silicon chip top, a pair of collimation optical 4 is positioned at the centre of light probe array 5, along the Y-axis symmetry, and the 5 rectangular arrangements of light probe array.Collimation optical 4 has reading device 7, and this device comprises light source 51, diverging lens 52, polarization spectroscope 53, quarter-wave plate 54, condenser lens 56 and photodetector 57.Light source 51 reads signal by diverging lens 52, form directional light, this directional light passes through polarization spectroscope 53, quarter-wave plate 54, condenser lens 55 backs at alignment pattern place flat focus, reflected light is by condenser lens 55, quarter-wave plate 54 and polarization spectroscope 53, and lens 56, shine on the photodetector 57.

This calibrating installation job step is as follows:

1, whole device as shown in Figure 1.Silicon chip is installed in the worktable position that is installed on the right side, carries out pre-determined bit by prealignment device, and travelling table enters the left side and inscribes the position then.

2, adjust two a collimation optical spacing, make the inscription position of two optical heads at silicon chip edge, to adapt to the silicon chip of different size.When inscribing first,, write alignment pattern next door blank position at first with codings such as setting base, silicon chip information, graphical informations.The light probe array is inscribed circuitous pattern then, and two collimation optical heads are inscribed a pair of calibration spirte respectively with high power.As shown in Figure 3.It is circular aiming at spirte, as shown in Figure 6.

3, Computer Analysis circuitous pattern is selected several Key Points.Inscribe in the circuitous pattern process at the light probe array, when running into selecteed key point, the collimation optical head writes a pair of calibration spirte again.

4, repeating step 3, finish until the inscription of entire circuit figure.Comprise N calibration spirte in the alignment pattern, the quantity of N is relevant with circuitous pattern, shown in calibration graphics sub enlarged drawing among Fig. 4.In partial enlarged drawing, a calibration of each circle 11 expression spirte.

5, for the second time or when inscribing for the N time, when locating for the first time, at first in the position that is installed the silicon chip on the worktable is carried out prealignment by prealignment device, travelling table is to the inscription position.By at X, Y directional trim worktable, at first find the coded message band, read basic point coordinate, silicon chip and circuitous pattern information, destroy alignment pattern when avoiding reading signal, should read with weak power (Writing power 1/50th arrives one of percentage), the reading device optical principle as shown in Figure 5.Find first pair of calibration spirte again, according to the deviation signal that photodetector is measured, the X-Y-Rz direction is adjusted worktable synchronously, finishes alignment work.The photodetector principle of work is as follows: the collimation optical head that is positioned at the X positive dirction adopts 4 quadrant detector, as (A+B) during with (C+D) figure balance, shows that directions X calibrates; As (A+C) during, show that the Y direction calibrates with (B+D) figure balance.The collimation optical head that is positioned at the X negative direction adopts four-quadrant photo detector equally, as (A+C) during with (B+D) figure balance, shows that the Rz direction calibrates, and this moment, this finished calibration to alignment pattern.Shown among Fig. 6 61.

6, for the second time or when inscribing for the N time,, then calibrate once more according to the calibration spirte of inscription in the 3rd step if inscribe the key point that proceeds to circuitous pattern.Calibration steps is identical with the 5th step once more.If finding error in the calibration process once more, after Computer Processing, adjust light probe array and silicon chip relative position, error is compensated.

7, adopting the Astigmatism methord focusing, utilize the astigmatism element, is the change transitions of object lens defocusing amount the luminous energy variation of different directions, detects through photodetector, obtains error signal.

This method key is aligning and Computer Processing are combined closely, and a plurality of calibration spirtes are arranged in a pair of alignment pattern, and the quantity of calibration spirte is relevant with circuitous pattern, can repeatedly calibrate in once inscribing, and can improve alignment precision greatly.

Introduce an embodiment of the present invention below.

Use the 407nm light source, numerical aperture is that 0.95 object lens are formed single light probe, and the array of 40 * 40 probe groups squarelys is inscribed.Distance can be adjusted between 8mm-20mm between each probe unit.

The physical dimension of worktable is roughly 700mm * 400mm, kinematic accuracy is 0.02 μ m, movement velocity is 1000mm/s during scanning, line width is adjustable, inscribe the circuit unit of a 20mm * 20mm size, only need about 10 minutes, so and this also is the time of finishing chip photoetching on the silicon chip simultaneously.

The collimation optical head adopts the 407nm laser instrument, Writing power 8mw, and readout power 0.1mw aims at time 50ms.

Claims (2)

1, a kind of alignment device that is used for array type optical probe scanning IC photoetching system is characterized in that this device comprises pedestal, worktable, light probe array and collimation optical head; Described worktable is placed on the pedestal, by the elaborate servo motor-driven, move along X, Y direction, silicon chip to be processed is fixed on the worktable by sucker, described collimation optical head and light probe array are positioned at the silicon chip top, a pair of collimation optical head is positioned in the middle of the light probe array, along the Y-axis symmetry, and the rectangular arrangement of light probe array.

2, alignment device as claimed in claim 1 is characterized in that wherein said collimation optical headband has reading device, and this device comprises light source, diverging lens, polarization spectroscope, quarter-wave plate, condenser lens and photodetector; Described light source reads becomes directional light after signal sees through diverging lens, and this directional light sees through behind polarization spectroscope, quarter-wave plate and the condenser lens flat focus at the alignment pattern place successively; Reflected light sees through condenser lens, quarter-wave plate and polarization spectroscope successively, and incides on the photodetector behind the lens.

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