CN103558740A - Double-surface stepping photo-etching method for micro electro mechanical system (MEMS) wafer - Google Patents

Abstract

The invention relates to a double-surface stepping photo-etching method for a micro electro mechanical system (MEMS) wafer. The method is characterized by comprising the following steps: (a) carrying out photo-etching on the front surface of a wafer in a projection stepping photo-etching machine to manufacture an alignment mark (a,a) and a device structure; (b) manufacturing a corresponding alignment mark (b,b) on the back surface of the wafer in a double-surface photo-etching machine; (c) aligning the alignment mark (b,b) on the back surface of the wafer in the projection stepping photo-etching machine, and carrying out photo-etching on the back surface of the wafer to manufacture a corresponding device structure. According to the method, by using a double-surface photo-etching technology, double-surface structures can be manufactured in a projection stepping photo-etching process; the alignment mark is manufactured on the back surface of a double-surface photo-etching machine; high-accuracy overlay manufacturing is performed on the front and back surfaces of the wafer through the projection stepping photo-etching machine.

Description

The two-sided stepping photoetching method of a kind of MEMS disk

Technical field

The present invention relates to microelectronics MEMS device making technics technical field, particularly a kind of MEMS device is realized the technique processing method that step projection photoetching machine carries out dual surface lithography.

Background technology

In the face of the development trend that more and more less, the integrated difficulty of chip minimum dimension is more and more higher, disk size is increasing, high-precision MEMS device making technics advantage is more obvious.Stepper lithography system is a kind of mixing apparatus, has merged projection mask aligner and Wafer Stepper technology, by using the field picture that exposes completely of reducing glass scanning to realize to wafer.The automatic alignment apparatus of step photo-etching machine can guarantee to make reticule figure resembling on slice, thin piece to overlap in 0.1 μ m, and resolution is high, reaches sub-micrometer scale; Meanwhile, in whole scanning process, there is the ability regulate focusing on, lens defect and wafer leveling degree are changed be compensated etc.In addition, step photo-etching machine also has can select exposure area as required, can on projection mask, place a plurality of figures, and single exposure is crossed the advantages such as a chip.Future development, chip density is high, accurate, and disk area is increasing, and large visual field optical system and electron beam scanning can be made the very complicated circuit that is less than micron figure.But general step photo-etching machine can not carry out dual surface lithography technique, can not meet MEMS structural manufacturing process and make.

Double face photoetching machine can carry out the making of dual surface lithography technique, meets MEMS structure fabrication.In the evolution of double face photoetching machine, its alignment principles has four kinds of modes: infrared ray double-sided alignment, four object lens alignings, two mask alignment and bottom alignment.Infrared ray double-sided alignment is to utilize the penetrative characteristic of infrared ray tool, figure with infraed microscope from top view substrate back, reach the object of aiming at mask plate patterns, its advantage is directly whether to observe aligning, but can only be for the good substrate of transmittance.It is to select four high resolving power object lens as special-purpose alignment image that four object lens are aimed at, up and down design in pairs.Its advantage is that alignment precision is high, but production efficiency is low.Two mask alignment have adopted double-exposure system to expose simultaneously, and its advantage is that production efficiency is high and be not subject to the impact of substrate material and thickness, but exposure resolution ratio low (5 microns).Bottom alignment is after mask loading is fixed, adjust respectively bottom alignment microscope left and right object lens, make alignment mark blur-free imaging on mask in monitor, preserve alignment mark image, insert substrate, adjust substrate and alignment mark, thereby reach the requirement of double-sided alignment, bottom alignment adopts ccd image treatment technology, greatly improve alignment precision (being less than 1.5 microns), 1.5 microns of its face exposure resolutions, but its precision is far below step projection photoetching machine, can not select as required exposure area, do not possess the function of offset lens defect and the variation of wafer leveling degree etc. yet.

Summary of the invention

Object of the present invention is exactly can not carry out in order to solve general step photo-etching machine the problem that MEMS dual surface lithography carries out body structure making.

The technical solution adopted for the present invention to solve the technical problems is:

The two-sided stepping photoetching method of disk, is characterized in that comprising the following steps:

A. wafer carries out positive photoetching at step projection photoetching machine, produces alignment mark (a, a) and device architecture;

B. in double face photoetching machine, corresponding alignment mark (b, b) is produced in the wafer back side;

C. in step projection photoetching machine, aim at the alignment mark (b, b) at the wafer back side, at the corresponding device architecture of wafer back side photoetching.

The present invention is in conjunction with dual surface lithography technology, realizes bilateral structure and make in the processing of projection stepping photoetching process.Adopt double face photoetching machine to make overleaf an alignment mark, disk tow sides are used step projection photoetching machine to carry out the making of degree of precision alignment process.

Beneficial effect of the present invention: carry out the processing of MEMS body structure with independent employing double face photoetching machine and compare, improved processes precision; Carry out processes with the general step projection photoetching machine of independent employing and compare, when guaranteeing high-precision processes, realized the ability of its two-sided processing.The inventive method is simple, and technology is all utilized known MEMS technology, applied widely, is particularly useful in the MEMS element manufacturing of volume production degree of precision.

Accompanying drawing explanation

Fig. 1 to Fig. 7 is specific embodiment of the invention step;

Fig. 5 is that the present invention makes signal schematic diagram in double face photoetching machine back side photoetching alignment mark, wherein exposure system 1 be placed in mask 2 and silicon chip 3 directly over, two cover CCD imaging devices 9, 10 and two cover imaging optical systems 7, 8 be placed in mask 2 and silicon chip 3 under, two cover CCD imaging devices 9, 10 by two cover imaging optical systems 7, 8 absorb respectively the left and right alignment mark a of mask 2 and silicon chip 3 bottom surfaces, a, by image pick-up card 11 acquisition of image data, input in computing machine 12, by the mask that shows on computer screen and the relative position error of silicon chip left and right alignment mark image, adjust again the position of silicon chip, finally realize the overlay alignment of silicon chip and mask.

Embodiment:

1. affine, the even glue in wafer front after cleaning as shown in Figure 1;

2. as shown in Figure 2, in step projection photoetching machine, with I mask to the exposure of wafer A face, develop, then etch wafer A in the face of accurate pictorial symbolization (a, a) and device architecture;

3. as shown in Figure 3, remove photomask surface glue, cleaning;

4. wafer is affine, the even glue of back surface B as shown in Figure 4;

5. as shown in Figure 5,

In double face photoetching machine, first by the alignment mark (b of II mask, b) by the storage of shooting acquisition system and computer, and in computer monitor 12, show alignment mark (b, b), the alignment mark (b, b) of II mask and the alignment mark of I mask plate (a, a) identical.

Then by wafer A placed face down on wafer-supporting platform 6, by the alignment mark (a of shooting acquisition system Real-time Collection wafer A face, a), by precision, adjust the position of wafer-supporting platform 6 and move wafer, make the alignment mark (a of the wafer A of demonstration in display 12, a) with the accurate alignment of the alignment mark (b, b) of II mask, completed the aligning of wafer A, B face.

Finally utilize double face photoetching machine to pass through II mask in the exposure of wafer back surface B, development, make corresponding alignment mark (b, b), as shown in Figure 6.

6. as shown in Figure 7, in wafer back surface B, etch corresponding alignment mark (b, b), alignment mark (a, a) overlay alignment of it and wafer A face.

7. utilize in step projection photoetching machine, by the alignment mark (b of wafer B face, b) with III mask alignment mark (alignment mark of III mask and II mask alignment mark are overlay alignment relations), to the exposure of wafer B face, development, then etch the device architecture of wafer B face.

Claims (1)

1. the two-sided stepping photoetching method of MEMS disk, is characterized in that comprising the following steps:

A. wafer carries out positive photoetching at step projection photoetching machine, produces alignment mark (a, a) and device architecture;

B. in double face photoetching machine, at the wafer back side, produce corresponding alignment mark (b, b);

C. in step projection photoetching machine, aim at the alignment mark (b, b) at the wafer back side, at wafer back light, carve corresponding device architecture.

Images