JPS6292315A - Correction method and correction circuit for position of projection of charged beam - Google Patents

Abstract

PURPOSE:To reduce the scale of a digital circuit by computing a deflection strain correction factor except secondary order or more of deflection strain correction of pattern-position data by height and obtaining input data for a positional pattern in which deflection strain is corrected. CONSTITUTION:The position of projection of charged beams is corrected by an arithmetic circuit for correcting deflection strain. The height of an irradiation region is measured regarding an upper surface and a low surface at that time, thus acquiring deflection strain. A deflection strain correction factor except secondary order or more of deflection strain correction of pattern-position data by height is computed. Consequently, input data for a positional pattern in which deflection strain is corrected are obtained. Accordingly, the scale of a digital circuit is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and a correction circuit for correcting the irradiation position of a charged beam irradiation device necessary for manufacturing semiconductor integrated circuits and the like.

[Conventional technology]

Exposure apparatuses using charged beams include ion beam exposure apparatuses and electron beam seismic apparatuses, but here, conventional techniques will be explained using an electron beam exposure apparatus as an example.

When exposing a pattern on a sample surface using an electron beam haze device, it is required to position the beam with high precision to the position where the pattern is to be reflected. Since there is a deflection distortion in , it is necessary to correct the 1-th deflection distortion. The conventional deflection distortion correction method is described by Baka Takagi, "High Precision Electron Beam Reflector - EB55 (Research and Practical Application Report, Vol. 30, No. 7,
p, 18: (: (, 1981) The height is above. When drawing a pattern directly on a silicon wafer using an electron beam haze optical device, the wafer indicated by - is deformed three-dimensionally. It is necessary to correct the deflection distortion according to the height of the deflection distortion.Standard marks for measuring the above deflection distortion are shown in Fig. 2.In Fig. 2, 1 is the top table of the XY stage, 2 is the wafer, and 3 is the top table of the XY stage. In the mirror for laser length measurement, 10 is a standard mark on the lower side, and 20 is a standard mark on the higher side.Standard marks 10 and 20 are fixed on the above-mentioned tiger and buttock pull 1.Standard mark 10 and standard mark The difference in height from 20 is about 200 m.

In the pattern data input to the electron beam haze device, data representing the position of the pattern to be exposed is (,X,Y).
shall be. Convert (X, Y) to (X /, y'), and (
When the beam is deflected using input data (X', Y') to the beam deflector, the irradiation position on the sample surface becomes (x, Y').
y). Therefore, (X, Y) becomes (X',
The deflection distortion correction formula to convert to Y') is: X'=X+Ao+A□X+A2Y+A3X20A4X,
Y+A5Y2+A, X3 +A, X"Y+A, X, Y"+A, Y3Y'=Y+Bo
+B1X+R2Y+B3X”+114XY +115Y
2+BbXJ +13□X2Y+I(llXY2+lS, Y3...
... Represented by ('l). Here the coefficient Ai, 13; (] −0
~9) are deflection distortion correction coefficients. Deflection distortion is standard mark 1
Using 0 and 20, high and low 2 and skill? I ask. The deflection distortion correction coefficient calculated from the deflection distortion measured with the standard mark 10 using the laser length measurement mirror
(i=0 to 9), the deflection distortion correction coefficient calculated from the deflection distortion measured with the standard mark 20, A old, B old (i-0 to 9)
shall be. The height of standard mark 10 is z = L, standard mark 2
If the height of 0 is Z=H, and the deflection distortion correction coefficients at any height Z are A Z i, Bzl (i=o-9), then A Z i, B 2 i are the following complementary equations. It is determined by

(2) When exposing a pattern on the wafer 2 using an electron beam exposure device, first the height Z of the area where the pattern is to be exposed is measured using the laser length measuring mirror 3. Next, the deflection distortion correction coefficients A, Z i, Bz at the height Z measured from equation (2)
; Calculate (i = O-9), and calculate the coefficient At of equation (1),
B; A 2 i, nzr (j=
Substitute 0 to 9). And the coefficient A Z i, nz; (
The pattern position data (X, Y) is converted into (X/, y/) using equation (1) with i=o to 9). (1
) conversion of pattern position data using equation (2) and calculation of the deflection distortion correction coefficient using equation (2) need to be executed at high speed. It has several digital circuits. The configuration of this digital circuit is shown in FIG. In order to enable high-speed calculation, the calculation circuit of equation (2) is provided for each deflection distortion correction coefficient.

[Problem that the invention seeks to solve]

The above deflection distortion correction is applied to an electron beam exposure apparatus that uses one electron beam. By the way, in an electron beam haze device that simultaneously generates and controls a plurality of electron beams, it is important to reduce the scale of the digital circuit in order to significantly reduce manufacturing costs. If a digital circuit that performs a conventional deflection distortion correction method is applied as is to an electron beam exposure apparatus that uses a plurality of electron beams, the scale of the digital circuit would become enormous and would be impractical.

[Means for solving problems]

The present invention provides deflection distortion correction of an electron beam irradiation position.
After discovering that the deflection distortion of higher-order terms hardly changes with height, conventional technology corrects the distortion of higher-order terms for height, but the distortion for height is not corrected for higher-order terms. In this way, the scale of the digital circuit is reduced to correct the electron beam irradiation position.

[Effect]

Figure 4 shows the results of measuring deflection distortion using standard marks on two high and low surfaces. If the height of the standard mark on the lower side is 2=[, and the height of the standard mark on the higher side is expressed as z=H, then z=r
, and z=kT is about 200p.

The dimensions of the deflection field 1 of the electron beam exposure apparatus used for the 8111 length were 2.6 mm x 2.6 ml. Deflection distortion was measured at 5×5 grid points within the deflection field. The deflection distortion shown in FIG. 4 is corrected using equation (1). FIG. 5 shows correction coefficients for correcting the deflection distortion shown in FIG. 4. The deflection distortion correction coefficient in Fig. 5 is A in equation (2).
Corresponds to 口, PI l-i, A old, But (i=o~9). Next, the pattern position data is (X, Y) =:
For the case of (1250 Cape, 12507m), (1)
The amount that each term on the right side of the equation contributes to the correction amount of deflection distortion is determined using the deflection distortion correction coefficient shown in FIG. 5, and the results are shown in FIG. In Figure 6, A, X2°A4XY%A5Y2,
AGX', A7X2Y, Al1xY2, A, Y3, B
3x2, B, XY, B, Y2, B, X3, B7X”Y,
The contribution for each term of B, XY'', B, Y3 is z=r
, and z=H are almost the same, and the difference between them is at most 0.
It is 02#I11. Pattern position data (X, Y)
= (1250 prisoners, 1250 prisoners) is a value close to the maximum among the pattern position data. Therefore, X, Y
It is established within the deflection field that the second-order or higher distortion of Z = L and 2 = T (to within 0.02 degrees). In other words, the deflection distortion correction coefficients (A3-Ag, B3-B,) 11h of z=r or 2=T (11h) may be used for z=r or 2=T (11h), and calculation of the deflection distortion correction coefficient of the height Z using equation (2), which was performed in the conventional deflection distortion correction, becomes unnecessary.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a deflection distortion correction circuit of an electron beam irradiation apparatus according to the present invention. In the electron beam irradiation apparatus according to the present invention, in the digital circuit implementing the deflection distortion correction circuit shown in FIG.
3, B a - B s ), it does not have a digital circuit part for calculating equation (2). The deflection distortion correction coefficients (AI-3 to Al-5, BL, to nLs) are directly set in the deflection distortion correction calculation circuit. By doing this, in this embodiment, the pattern position data is
Although the deflection distortion correction of (2) is omitted, the calculation circuit of equation (2) is as shown in Fig. 1.
o, BZx, and BZa are all you need. Although at least one multiplier is required to calculate equation (2), the deflection distortion correction digital circuit according to the present invention requires 14 fewer multipliers than the conventional device as described above. Also, the number of registers for storing correction coefficients is 14 fewer than in the conventional case.

The electron beam exposure apparatus described above uses one electron beam, but when the present invention is applied to an electron beam exposure apparatus using multiple electron beams, the number of multipliers and The effect of reducing the number of registers is remarkable, and the effect of reducing the cost of digital circuits is remarkable.

Although the above description and embodiments have all been described with respect to an electron beam exposure apparatus, the same applies not only to electron beam exposure apparatuses but also to correction of the irradiation position of a charged beam irradiation apparatus.

〔Effect of the invention〕

As described above, the charged beam irradiation position correction method and correction circuit according to the present invention have a charged beam irradiation position correction force method and a correction circuit that have an arithmetic circuit for correcting deflection distortion. The deflection distortion is determined by measuring the lower surface of the pattern, and by calculating the deflection distortion correction coefficient excluding the secondary or higher order deflection distortion correction of the pattern position data based on the recorded height, the position pattern with the deflection distortion corrected is calculated. In order to obtain input data, the digital circuit described above can be achieved by omitting the digital circuit that corrects the second-order or higher deflection distortion of the pattern position data (x, y) that does not require correction for the height Z, and by reducing the scale of the digital circuit. cost can be reduced. Note that when the present invention is applied to a charged beam irradiation device that generates a plurality of beams, the effect of reducing the scale of the digital circuit and cost is even more remarkable.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of a deflection distortion correction circuit in an electron beam irradiation device according to the present invention, Fig. 2 is a model diagram of a standard mark with two high and low surfaces, and Fig. 3 is a conventional charged beam irradiation position deflection diagram. A configuration diagram showing the distortion correction circuit, Fig. 4 shows the deflection distortion determined by standard mark fil11, No. 5V4 shows the correction coefficient for correcting the deflection distortion, and Fig. 6 shows the correction amount of the deflection distortion. Contribution 3...Mirror for laser length measurement 10...Height of the irradiation area (lower surface) 20...Height of the irradiation area (1 side) Patent applicant Junnosuke Nakamura, Patent attorney representing Nippon Telegraph and Telephone Corporation 1, 22 figures, 3 figures

Claims (2)

[Claims] (1) In a charged beam irradiation position correction method that has an arithmetic circuit for correcting deflection distortion, the height of the irradiation area is measured on the upper and lower surfaces to obtain deflection distortion, and the pattern position data based on the height is calculated by A charged beam irradiation position correction method characterized in that input data of a position pattern with deflection distortion corrected is obtained by calculating a deflection distortion correction coefficient excluding the above deflection distortion correction. (2) In a charged beam irradiation position correction circuit that has an arithmetic circuit for correcting deflection distortion, the digital circuit that corrects deflection distortion based on the height of the irradiation area does not correct secondary or higher order deflection distortion of pattern position data. A charged beam irradiation position correction circuit comprising a correction coefficient register and a deflection distortion correction coefficient calculation circuit.